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Hoque MM, Noorian P, Espinoza-Vergara G, Adhikary S, To J, Rice SA, McDougald D. Increased iron utilization and oxidative stress tolerance in a Vibrio cholerae flrA mutant confers resistance to amoeba predation. Appl Environ Microbiol 2023; 89:e0109523. [PMID: 37882527 PMCID: PMC10686080 DOI: 10.1128/aem.01095-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Accepted: 09/15/2023] [Indexed: 10/27/2023] Open
Abstract
IMPORTANCE Persistence of V. cholerae in the aquatic environment contributes to the fatal diarrheal disease cholera, which remains a global health burden. In the environment, bacteria face predation pressure by heterotrophic protists such as the free-living amoeba A. castellanii. This study explores how a mutant of V. cholerae adapts to acquire essential nutrients and survive predation. Here, we observed that up-regulation of iron acquisition genes and genes regulating resistance to oxidative stress enhances pathogen fitness. Our data show that V. cholerae can defend predation to overcome nutrient limitation and oxidative stress, resulting in an enhanced survival inside the protozoan hosts.
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Affiliation(s)
- M. Mozammel Hoque
- Australian Institute for Microbiology and Infection, University of Technology Sydney, Sydney, NSW, Australia
| | - Parisa Noorian
- Australian Institute for Microbiology and Infection, University of Technology Sydney, Sydney, NSW, Australia
| | - Gustavo Espinoza-Vergara
- Australian Institute for Microbiology and Infection, University of Technology Sydney, Sydney, NSW, Australia
| | - Srijon Adhikary
- Australian Institute for Microbiology and Infection, University of Technology Sydney, Sydney, NSW, Australia
| | - Joyce To
- Australian Institute for Microbiology and Infection, University of Technology Sydney, Sydney, NSW, Australia
| | - Scott A. Rice
- Australian Institute for Microbiology and Infection, University of Technology Sydney, Sydney, NSW, Australia
- CSIRO Animal, Food and Health Sciences, Westmead, NSW, Australia
| | - Diane McDougald
- Australian Institute for Microbiology and Infection, University of Technology Sydney, Sydney, NSW, Australia
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2
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Fong J, Tang PPY, Deignan LK, Seah JCL, McDougald D, Rice SA, Todd PA. Chemically Mediated Interactions with Macroalgae Negatively Affect Coral Health but Induce Limited Changes in Coral Microbiomes. Microorganisms 2023; 11:2261. [PMID: 37764105 PMCID: PMC10535309 DOI: 10.3390/microorganisms11092261] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2023] [Revised: 09/05/2023] [Accepted: 09/06/2023] [Indexed: 09/29/2023] Open
Abstract
Allelopathic chemicals facilitated by the direct contact of macroalgae with corals are potentially an important mechanism mediating coral-macroalgal interactions, but only a few studies have explored their impacts on coral health and microbiomes and the coral's ability to recover. We conducted a field experiment on an equatorial urbanized reef to assess the allelopathic effects of four macroalgal species (Bryopsis sp., Endosiphonia horrida, Hypnea pannosa and Lobophora challengeriae) on the health and microbiomes of three coral species (Merulina ampliata, Montipora stellata and Pocillopora acuta). Following 24 h of exposure, crude extracts of all four macroalgal species caused significant coral tissue bleaching and reduction in effective quantum yield. The corals were able to recover within 72 h of the removal of extracts, except those that were exposed to L. challengeriae. While some macroalgal extracts caused an increase in the alpha diversity of coral microbiomes, there were no significant differences in the composition and variability of coral microbiomes between controls and macroalgal extracts at each sampling time point. Nevertheless, DESeq2 differential abundance analyses showed species-specific responses of coral microbiomes. Overall, our findings provide insights on the limited effect of chemically mediated interactions with macroalgae on coral microbiomes and the capacity of corals to recover quickly from the macroalgal chemicals.
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Affiliation(s)
- Jenny Fong
- Experimental Marine Ecology Laboratory, National University of Singapore, Singapore 117558, Singapore; (J.C.L.S.); (P.A.T.)
| | - Peggy P. Y. Tang
- Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore 637551, Singapore; (P.P.Y.T.); (L.K.D.); (D.M.); (S.A.R.)
| | - Lindsey K. Deignan
- Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore 637551, Singapore; (P.P.Y.T.); (L.K.D.); (D.M.); (S.A.R.)
| | - Jovena C. L. Seah
- Experimental Marine Ecology Laboratory, National University of Singapore, Singapore 117558, Singapore; (J.C.L.S.); (P.A.T.)
| | - Diane McDougald
- Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore 637551, Singapore; (P.P.Y.T.); (L.K.D.); (D.M.); (S.A.R.)
- Australian Institute for Microbiology & Infection, University of Technology Sydney, Sydney, NSW 2007, Australia
| | - Scott A. Rice
- Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore 637551, Singapore; (P.P.Y.T.); (L.K.D.); (D.M.); (S.A.R.)
| | - Peter A. Todd
- Experimental Marine Ecology Laboratory, National University of Singapore, Singapore 117558, Singapore; (J.C.L.S.); (P.A.T.)
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3
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Hoque MM, Espinoza-Vergara G, McDougald D. Protozoan predation as a driver of diversity and virulence in bacterial biofilms. FEMS Microbiol Rev 2023; 47:fuad040. [PMID: 37458768 DOI: 10.1093/femsre/fuad040] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2023] [Revised: 06/19/2023] [Accepted: 07/07/2023] [Indexed: 07/27/2023] Open
Abstract
Protozoa are eukaryotic organisms that play a crucial role in nutrient cycling and maintaining balance in the food web. Predation, symbiosis and parasitism are three types of interactions between protozoa and bacteria. However, not all bacterial species are equally susceptible to protozoan predation as many are capable of defending against predation in numerous ways and may even establish either a symbiotic or parasitic life-style. Biofilm formation is one such mechanism by which bacteria can survive predation. Structural and chemical components of biofilms enhance resistance to predation compared to their planktonic counterparts. Predation on biofilms gives rise to phenotypic and genetic heterogeneity in prey that leads to trade-offs in virulence in other eukaryotes. Recent advances, using molecular and genomics techniques, allow us to generate new information about the interactions of protozoa and biofilms of prey bacteria. This review presents the current state of the field on impacts of protozoan predation on biofilms. We provide an overview of newly gathered insights into (i) molecular mechanisms of predation resistance in biofilms, (ii) phenotypic and genetic diversification of prey bacteria, and (iii) evolution of virulence as a consequence of protozoan predation on biofilms.
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Affiliation(s)
- M Mozammel Hoque
- Australian Institute for Microbiology & Infection, University of Technology Sydney, Sydney, NSW 2007, Australia
| | - Gustavo Espinoza-Vergara
- Australian Institute for Microbiology & Infection, University of Technology Sydney, Sydney, NSW 2007, Australia
| | - Diane McDougald
- Australian Institute for Microbiology & Infection, University of Technology Sydney, Sydney, NSW 2007, Australia
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4
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Gilmore BF, McDougald D, Beloin C. Editorial: Insights in biofilms: 2021. Front Cell Infect Microbiol 2022; 12:1093692. [PMID: 36506017 PMCID: PMC9727399 DOI: 10.3389/fcimb.2022.1093692] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Accepted: 11/14/2022] [Indexed: 11/25/2022] Open
Affiliation(s)
- Brendan F. Gilmore
- Queen’s University Belfast, School of Pharmacy, Biofilm Research Group, Belfast, United Kingdom
| | - Diane McDougald
- Australian Institute for Microbiology & Infection, University of Technology Sydney, Sydney, NSW, Australia
| | - Christophe Beloin
- Institut Pasteur, Université de Paris Cité, UMR CNRS 6047, Genetics of Biofilms Laboratory, Paris, France,*Correspondence: Christophe Beloin,
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5
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Summers S, Pek YS, Vinod DP, McDougald D, Todd PA, Birch WR, Rice SA. Bacterial biofilm colonization and succession in tropical marine waters are similar across different types of stone materials used in seawall construction. Front Microbiol 2022; 13:928877. [PMID: 35958146 PMCID: PMC9358718 DOI: 10.3389/fmicb.2022.928877] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Accepted: 07/07/2022] [Indexed: 11/13/2022] Open
Abstract
Seawalls are important in protecting coastlines from currents, erosion, sea-level rise, and flooding. They are, however, associated with reduced biodiversity, due to their steep orientation, lack of microhabitats, and the materials used in their construction. Hence, there is considerable interest in modifying seawalls to enhance the settlement and diversity of marine organisms, as microbial biofilms play a critical role facilitating algal and invertebrate colonization. We assessed how different stone materials, ranging from aluminosilicates to limestone and concrete, affect biofilm formation. Metagenomic assessment of marine microbial communities indicated no significant impact of material on microbial diversity, irrespective of the diverse surface chemistry and topography. Based on KEGG pathway analysis, surface properties appeared to influence the community composition and function during the initial stages of biofilm development, but this effect disappeared by Day 31. We conclude that marine biofilms converged over time to a generic marine biofilm, rather than the underlying stone substrata type playing a significant role in driving community composition.
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Affiliation(s)
- Stephen Summers
- Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore, Singapore
| | - Y. Shona Pek
- Institute of Materials Research and Engineering, Agency for Science, Technology and Research (A*STAR), Singapore, Singapore
| | - Deepthi P. Vinod
- School of Bioscience and Technology, Vellore Institute of Technology, Vellore, India
| | - Diane McDougald
- Australian Institute for Microbiology and Infection, The University of Technology Sydney, Sydney, NSW, Australia
| | - Peter A. Todd
- Department of Biological Sciences, National University of Singapore, Singapore, Singapore
| | - William R. Birch
- Institute of Materials Research and Engineering, Agency for Science, Technology and Research (A*STAR), Singapore, Singapore
| | - Scott A. Rice
- Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore, Singapore
- Agriculture and Food, Microbiomes for One Systems Health, Commonwealth Scientific and Industrial Research Organisation (CSIRO), Canberra, ACT, Australia
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Deignan LK, McDougald D. Differential Response of the Microbiome of Pocillopora acuta to Reciprocal Transplantation Within Singapore. Microb Ecol 2022; 83:608-618. [PMID: 34148107 PMCID: PMC8979861 DOI: 10.1007/s00248-021-01793-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2021] [Accepted: 06/10/2021] [Indexed: 05/07/2023]
Abstract
As corals continue to decline globally, particularly due to climate change, it is vital to understand the extent to which their microbiome may confer an adaptive resilience against environmental stress. Corals that survive on the urban reefs of Singapore are ideal candidates to study the association of scleractinians with their microbiome, which in turn can inform reef conservation and management. In this study, we monitored differences in the microbiome of Pocillopora acuta colonies reciprocally transplanted between two reefs, Raffles and Kusu, within the Port of Singapore, where corals face intense anthropogenic impacts. Pocillopora acuta had previously been shown to host distinct microbial communities between these two reefs. Amplicon sequencing (16S rRNA) was used to assess the coral microbiomes at 1, 2, 4, and 10 days post-transplantation. Coral microbiomes responded rapidly to transplantation, becoming similar to those of the local corals at the destination reef within one day at Raffles and within two days at Kusu. Elevated nitrate concentrations were detected at Raffles for the duration of the study, potentially influencing the microbiome's response to transplantation. The persistence of corals within the port of Singapore highlights the ability of corals to adapt to stressful environments. Further, coral resilience appears to coincide with a dynamic microbiome which can undergo shifts in composition without succumbing to dysbiosis.
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Affiliation(s)
- Lindsey K Deignan
- Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, 60 Nanyang Drive, SBS-01N-27, Singapore, 637551, Singapore.
| | - Diane McDougald
- Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, 60 Nanyang Drive, SBS-01N-27, Singapore, 637551, Singapore
- The iThree Institute, University of Technology Sydney, Sydney, NSW, 2007, Australia
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7
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Hoque MM, Noorian P, Espinoza-Vergara G, Manuneedhi Cholan P, Kim M, Rahman MH, Labbate M, Rice SA, Pernice M, Oehlers SH, McDougald D. Adaptation to an amoeba host drives selection of virulence-associated traits in Vibrio cholerae. ISME J 2022; 16:856-867. [PMID: 34654895 PMCID: PMC8857207 DOI: 10.1038/s41396-021-01134-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Revised: 09/20/2021] [Accepted: 09/29/2021] [Indexed: 12/02/2022]
Abstract
Predation by heterotrophic protists drives the emergence of adaptive traits in bacteria, and often these traits lead to altered interactions with hosts and persistence in the environment. Here we studied adaptation of the cholera pathogen, Vibrio cholerae during long-term co-incubation with the protist host, Acanthamoeba castellanii. We determined phenotypic and genotypic changes associated with long-term intra-amoebal host adaptation and how this impacts pathogen survival and fitness. We showed that adaptation to the amoeba host leads to temporal changes in multiple phenotypic traits in V. cholerae that facilitate increased survival and competitive fitness in amoeba. Genome sequencing and mutational analysis revealed that these altered lifestyles were linked to non-synonymous mutations in conserved regions of the flagellar transcriptional regulator, flrA. Additionally, the mutations resulted in enhanced colonisation in zebrafish, establishing a link between adaptation of V. cholerae to amoeba predation and enhanced environmental persistence. Our results show that pressure imposed by amoeba on V. cholerae selects for flrA mutations that serves as a key driver for adaptation. Importantly, this study provides evidence that adaptive traits that evolve in pathogens in response to environmental predatory pressure impact the colonisation of eukaryotic organisms by these pathogens.
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Affiliation(s)
- M. Mozammel Hoque
- grid.117476.20000 0004 1936 7611The iThree Institute, University of Technology Sydney, Sydney, NSW Australia
| | - Parisa Noorian
- grid.117476.20000 0004 1936 7611The iThree Institute, University of Technology Sydney, Sydney, NSW Australia
| | - Gustavo Espinoza-Vergara
- grid.117476.20000 0004 1936 7611The iThree Institute, University of Technology Sydney, Sydney, NSW Australia
| | - Pradeep Manuneedhi Cholan
- grid.1013.30000 0004 1936 834XTuberculosis Research Program at the Centenary Institute, The University of Sydney, Camperdown, NSW Australia ,grid.1013.30000 0004 1936 834XFaculty of Medicine and Health & Marie Bashir Institute, The University of Sydney, Camperdown, NSW Australia
| | - Mikael Kim
- grid.117476.20000 0004 1936 7611Climate Change Cluster, University of Technology Sydney, Sydney, NSW Australia
| | - Md Hafizur Rahman
- grid.117476.20000 0004 1936 7611School of Life Sciences, Faculty of Science, University of Technology Sydney, Sydney, NSW Australia
| | - Maurizio Labbate
- grid.117476.20000 0004 1936 7611School of Life Sciences, Faculty of Science, University of Technology Sydney, Sydney, NSW Australia
| | - Scott A. Rice
- grid.117476.20000 0004 1936 7611The iThree Institute, University of Technology Sydney, Sydney, NSW Australia ,grid.59025.3b0000 0001 2224 0361Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore, Singapore
| | - Mathieu Pernice
- grid.117476.20000 0004 1936 7611Climate Change Cluster, University of Technology Sydney, Sydney, NSW Australia
| | - Stefan H. Oehlers
- grid.1013.30000 0004 1936 834XTuberculosis Research Program at the Centenary Institute, The University of Sydney, Camperdown, NSW Australia ,grid.1013.30000 0004 1936 834XFaculty of Medicine and Health & Marie Bashir Institute, The University of Sydney, Camperdown, NSW Australia
| | - Diane McDougald
- grid.117476.20000 0004 1936 7611The iThree Institute, University of Technology Sydney, Sydney, NSW Australia ,grid.59025.3b0000 0001 2224 0361Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore, Singapore
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8
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Nair HAS, Subramoni S, Poh WH, Hasnuddin NTB, Tay M, Givskov M, Tolker-Nielsen T, Kjelleberg S, McDougald D, Rice SA. Carbon starvation of Pseudomonas aeruginosa biofilms selects for dispersal insensitive mutants. BMC Microbiol 2021; 21:255. [PMID: 34551714 PMCID: PMC8459498 DOI: 10.1186/s12866-021-02318-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Accepted: 09/14/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Biofilms disperse in response to specific environmental cues, such as reduced oxygen concentration, changes in nutrient concentration and exposure to nitric oxide. Interestingly, biofilms do not completely disperse under these conditions, which is generally attributed to physiological heterogeneity of the biofilm. However, our results suggest that genetic heterogeneity also plays an important role in the non-dispersing population of P. aeruginosa in biofilms after nutrient starvation. RESULTS In this study, 12.2% of the biofilm failed to disperse after 4 d of continuous starvation-induced dispersal. Cells were recovered from the dispersal phase as well as the remaining biofilm. For 96 h starved biofilms, rugose small colony variants (RSCV) were found to be present in the biofilm, but were not observed in the dispersal effluent. In contrast, wild type and small colony variants (SCV) were found in high numbers in the dispersal phase. Genome sequencing of these variants showed that most had single nucleotide mutations in genes associated with biofilm formation, e.g. in wspF, pilT, fha1 and aguR. Complementation of those mutations restored starvation-induced dispersal from the biofilms. Because c-di-GMP is linked to biofilm formation and dispersal, we introduced a c-di-GMP reporter into the wild-type P. aeruginosa and monitored green fluorescent protein (GFP) expression before and after starvation-induced dispersal. Post dispersal, the microcolonies were smaller and significantly brighter in GFP intensity, suggesting the relative concentration of c-di-GMP per cell within the microcolonies was also increased. Furthermore, only the RSCV showed increased c-di-GMP, while wild type and SCV were no different from the parental strain. CONCLUSIONS This suggests that while starvation can induce dispersal from the biofilm, it also results in strong selection for mutants that overproduce c-di-GMP and that fail to disperse in response to the dispersal cue, starvation.
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Affiliation(s)
- Harikrishnan A S Nair
- The Singapore Centre for Environmental Life Sciences Engineering, Singapore, Singapore.,Interdisciplinary Graduate School, Singapore, Singapore.,Present address: Eppendorf AG, Barkhausenweg 1, 22339, Hamburg, Germany
| | - Sujatha Subramoni
- The Singapore Centre for Environmental Life Sciences Engineering, Singapore, Singapore
| | - Wee Han Poh
- The Singapore Centre for Environmental Life Sciences Engineering, Singapore, Singapore
| | | | - Martin Tay
- The Singapore Centre for Environmental Life Sciences Engineering, Singapore, Singapore.,Present address: Public Utilities Board, Government of Singapore, Singapore, Singapore
| | - Michael Givskov
- The Singapore Centre for Environmental Life Sciences Engineering, Singapore, Singapore.,Costerton Biofilm Center, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Tim Tolker-Nielsen
- Costerton Biofilm Center, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Staffan Kjelleberg
- The Singapore Centre for Environmental Life Sciences Engineering, Singapore, Singapore.,School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
| | - Diane McDougald
- The Singapore Centre for Environmental Life Sciences Engineering, Singapore, Singapore. .,The Ithree Institute, University of Technology Sydney, Sydney, Australia.
| | - Scott A Rice
- The Singapore Centre for Environmental Life Sciences Engineering, Singapore, Singapore. .,School of Biological Sciences, Nanyang Technological University, Singapore, Singapore. .,The Ithree Institute, University of Technology Sydney, Sydney, Australia.
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Ismail MH, Michie KA, Goh YF, Noorian P, Kjelleberg S, Duggin IG, McDougald D, Rice SA. The Repressor C Protein, Pf4r, Controls Superinfection of Pseudomonas aeruginosa PAO1 by the Pf4 Filamentous Phage and Regulates Host Gene Expression. Viruses 2021; 13:1614. [PMID: 34452479 PMCID: PMC8402870 DOI: 10.3390/v13081614] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Revised: 08/09/2021] [Accepted: 08/13/2021] [Indexed: 12/17/2022] Open
Abstract
It has been shown that the filamentous phage, Pf4, plays an important role in biofilm development, stress tolerance, genetic variant formation and virulence in Pseudomonas aeruginosa PAO1. These behaviours are linked to the appearance of superinfective phage variants. Here, we have investigated the molecular mechanism of superinfection as well as how the Pf4 phage can control host gene expression to modulate host behaviours. Pf4 exists as a prophage in PAO1 and encodes a homologue of the P2 phage repressor C and was recently named Pf4r. Through a combination of molecular techniques, ChIPseq and transcriptomic analyses, we show a critical site in repressor C (Pf4r) where a mutation in the site, 788799A>G (Ser4Pro), causes Pf4r to lose its function as the immunity factor against reinfection by Pf4. X-ray crystal structure analysis shows that Pf4r forms symmetric homo-dimers homologous to the E.coli bacteriophage P2 RepC protein. A mutation, Pf4r*, associated with the superinfective Pf4r variant, found at the dimer interface, suggests dimer formation may be disrupted, which derepresses phage replication. This is supported by multi-angle light scattering (MALS) analysis, where the Pf4r* protein only forms monomers. The loss of dimerisation also explains the loss of Pf4r's immunity function. Phenotypic assays showed that Pf4r increased LasB activity and was also associated with a slight increase in the percentage of morphotypic variants. ChIPseq and transcriptomic analyses suggest that Pf4r also likely functions as a transcriptional regulator for other host genes. Collectively, these data suggest the mechanism by which filamentous phages play such an important role in P. aeruginosa biofilm development.
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Affiliation(s)
- Muhammad Hafiz Ismail
- Singapore Centre for Environmental Life Sciences Engineering, Singapore 637551, Singapore; (M.H.I.); (Y.F.G.); (S.K.); (D.M.)
- The School of Biological Sciences, Nanyang Technological University, Singapore 637551, Singapore
| | - Katharine A. Michie
- Structural Biology Facility, Mark Wainwright Analytical Centre, The University of New South Wales, Sydney, NSW 2052, Australia;
| | - Yu Fen Goh
- Singapore Centre for Environmental Life Sciences Engineering, Singapore 637551, Singapore; (M.H.I.); (Y.F.G.); (S.K.); (D.M.)
| | - Parisa Noorian
- The iThree Institute, The University of Technology Sydney, Sydney, NSW 2007, Australia; (P.N.); (I.G.D.)
| | - Staffan Kjelleberg
- Singapore Centre for Environmental Life Sciences Engineering, Singapore 637551, Singapore; (M.H.I.); (Y.F.G.); (S.K.); (D.M.)
- The School of Biological Sciences, Nanyang Technological University, Singapore 637551, Singapore
| | - Iain G. Duggin
- The iThree Institute, The University of Technology Sydney, Sydney, NSW 2007, Australia; (P.N.); (I.G.D.)
| | - Diane McDougald
- Singapore Centre for Environmental Life Sciences Engineering, Singapore 637551, Singapore; (M.H.I.); (Y.F.G.); (S.K.); (D.M.)
- The iThree Institute, The University of Technology Sydney, Sydney, NSW 2007, Australia; (P.N.); (I.G.D.)
| | - Scott A. Rice
- Singapore Centre for Environmental Life Sciences Engineering, Singapore 637551, Singapore; (M.H.I.); (Y.F.G.); (S.K.); (D.M.)
- The School of Biological Sciences, Nanyang Technological University, Singapore 637551, Singapore
- The iThree Institute, The University of Technology Sydney, Sydney, NSW 2007, Australia; (P.N.); (I.G.D.)
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10
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Chan SH, Ismail MH, Tan CH, Rice SA, McDougald D. Microbial predation accelerates granulation and modulates microbial community composition. BMC Microbiol 2021; 21:91. [PMID: 33773594 PMCID: PMC8004422 DOI: 10.1186/s12866-021-02156-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Accepted: 03/08/2021] [Indexed: 11/26/2022] Open
Abstract
BACKGROUND Bacterial communities are responsible for biological nutrient removal and flocculation in engineered systems such as activated floccular sludge. Predators such as bacteriophage and protozoa exert significant predation pressure and cause bacterial mortality within these communities. However, the roles of bacteriophage and protozoan predation in impacting granulation process remain limited. Recent studies hypothesised that protozoa, particularly sessile ciliates, could have an important role in granulation as these ciliates were often observed in high abundance on surfaces of granules. Bacteriophages were hypothesized to contribute to granular stability through bacteriophage-mediated extracellular DNA release by lysing bacterial cells. This current study investigated the bacteriophage and protozoan communities throughout the granulation process. In addition, the importance of protozoan predation during granulation was also determined through chemical killing of protozoa in the floccular sludge. RESULTS Four independent bioreactors seeded with activated floccular sludge were operated for aerobic granulation for 11 weeks. Changes in the phage, protozoa and bacterial communities were characterized throughout the granulation process. The filamentous phage, Inoviridae, increased in abundance at the initiation phase of granulation. However, the abundance shifted towards lytic phages during the maturation phase. In contrast, the abundance and diversity of protozoa decreased initially, possibly due to the reduction in settling time and subsequent washout. Upon the formation of granules, ciliated protozoa from the class Oligohymenophorea were the dominant group of protozoa based on metacommunity analysis. These protozoa had a strong, positive-correlation with the initial formation of compact aggregates prior to granule development. Furthermore, chemical inhibition of these ciliates in the floccular sludge delayed the initiation of granule formation. Analysis of the bacterial communities in the thiram treated sludge demonstrated that the recovery of 'Candidatus Accumulibacter' was positively correlated with the formation of compact aggregates and granules. CONCLUSION Predation by bacteriophage and protozoa were positively correlated with the formation of aerobic granules. Increases in Inoviridae abundance suggested that filamentous phages may promote the structural formation of granules. Initiation of granules formation was delayed due to an absence of protozoa after chemical treatment. The presence of 'Candidatus Accumulibacter' was necessary for the formation of granules in the absence of protozoa.
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Affiliation(s)
- Siew Herng Chan
- Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, 60 Nanyang Drive, Singapore, 637551, Singapore
- Interdisciplinary Graduate School, Nanyang Technological University, Singapore, Singapore
| | - Muhammad Hafiz Ismail
- Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, 60 Nanyang Drive, Singapore, 637551, Singapore
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
| | - Chuan Hao Tan
- Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, 60 Nanyang Drive, Singapore, 637551, Singapore
- School of Materials Science and Engineering, Nanyang Technological University, Singapore, Singapore
| | - Scott A Rice
- Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, 60 Nanyang Drive, Singapore, 637551, Singapore.
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore.
- The iThree Institute, University of Technology Sydney, Sydney, Australia.
| | - Diane McDougald
- Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, 60 Nanyang Drive, Singapore, 637551, Singapore.
- The iThree Institute, University of Technology Sydney, Sydney, Australia.
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11
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Affiliation(s)
- Christophe Beloin
- Genetics of Biofilms Laboratory, Institut Pasteur, UMR CNRS2001, Paris, France
| | - Diane McDougald
- iîhree lnstitute, University of Technology Sydney, Sydney, NSW, Australia.,Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore, Singapore
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12
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Hardie KR, Mathee K, Schweizer HP, Dietrich LEP, Welch M, de Kievit T, Nguyen D, Kivisaar M, Dandekar AA, McDougald D, Winstanley C. Pseudomonas 2019 meeting report. J Med Microbiol 2020; 69:924-927. [PMID: 32490791 PMCID: PMC7481743 DOI: 10.1099/jmm.0.001208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Accepted: 05/06/2020] [Indexed: 11/29/2022] Open
Affiliation(s)
- Kim R. Hardie
- School of Life Sciences, Biodiscovery Institute, University Park, University of Nottingham, Nottingham, NG7 2RD, UK
| | - Kalai Mathee
- Herbert Wertheim College of Medicine, Florida International University, USA
| | - Herbert P. Schweizer
- Department of Molecular Genetics & Microbiology, College of Medicine, Emerging Pathogens Institute, University of Florida, Gainesville, FL 32610, USA
| | - Lars EP Dietrich
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA
| | - Martin Welch
- Department of Biochemistry, Tennis Court Road, University of Cambridge, Cambridge, UK
| | - Teresa de Kievit
- Department of Microbiology, University of Manitoba, Winnipeg, Canada
| | - Dao Nguyen
- Department of Medicine, McGill University, Montreal, Canada
| | - Maia Kivisaar
- Institute of Molecular and Cell Biology, University of Tartu, Tartu, Estonia
| | - Ajai A. Dandekar
- Department of Microbiology, University of Washington, Seattle, WA, USA
| | - Diane McDougald
- The Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore
- The ithree Institute, The University of Technology Sydney, Sydney, Australia
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13
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14
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Espinoza-Vergara G, Hoque MM, McDougald D, Noorian P. The Impact of Protozoan Predation on the Pathogenicity of Vibrio cholerae. Front Microbiol 2020; 11:17. [PMID: 32038597 PMCID: PMC6985070 DOI: 10.3389/fmicb.2020.00017] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2019] [Accepted: 01/07/2020] [Indexed: 12/16/2022] Open
Abstract
In the aquatic environment, Vibrio spp. interact with many living organisms that can serve as a replication niche, including heterotrophic protists, or protozoa. Protozoa engulf bacteria and package them into phagosomes where the cells are exposed to low pH, antimicrobial peptides, reactive oxygen/nitrogen species, proteolytic enzymes, and low concentrations of essential metal ions such as iron. However, some bacteria can resist these digestive processes. For example, Vibrio cholerae and Vibrio harveyi can resist intracellular digestion. In order to survive intracellularly, bacteria have acquired and/or developed specific factors that help them to resist the unfavorable conditions encountered inside of the phagosomes. Many of these intra-phagosomal factors used to kill and digest bacteria are highly conserved between eukaryotic cells and thus are also expressed by the innate immune system in the gastrointestinal tract as the first line of defense against bacterial pathogens. Since pathogenic bacteria have been shown to be hypervirulent after they have passed through protozoa, the resistance to digestion by protist hosts in their natural environment plays a key role in enhancing the infectious potential of pathogenic Vibrio spp. This review will investigate the current knowledge in interactions of bacteria with protozoa and human host to better understand the mechanisms used by both protozoa and human hosts to kill bacteria and the bacterial response to them.
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Affiliation(s)
- Gustavo Espinoza-Vergara
- Faculty of Science, The ithree Institute, University of Technology Sydney, Sydney, NSW, Australia
| | - M Mozammel Hoque
- Faculty of Science, The ithree Institute, University of Technology Sydney, Sydney, NSW, Australia
| | - Diane McDougald
- Faculty of Science, The ithree Institute, University of Technology Sydney, Sydney, NSW, Australia.,Faculty of Science, Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore, Singapore
| | - Parisa Noorian
- Faculty of Science, The ithree Institute, University of Technology Sydney, Sydney, NSW, Australia
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15
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Sun S, Noorian P, McDougald D. Dual Role of Mechanisms Involved in Resistance to Predation by Protozoa and Virulence to Humans. Front Microbiol 2018; 9:1017. [PMID: 29867902 PMCID: PMC5967200 DOI: 10.3389/fmicb.2018.01017] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Accepted: 04/30/2018] [Indexed: 12/12/2022] Open
Abstract
Most opportunistic pathogens transit in the environment between hosts and the environment plays a significant role in the evolution of protective traits. The coincidental evolution hypothesis suggests that virulence factors arose as a response to other selective pressures rather for virulence per se. This idea is strongly supported by the elucidation of bacterial-protozoal interactions. In response to protozoan predation, bacteria have evolved various defensive mechanisms which may also function as virulence factors. In this review, we summarize the dual role of factors involved in both grazing resistance and human pathogenesis, and compare the traits using model intracellular and extracellular pathogens. Intracellular pathogens rely on active invasion, blocking of the phagosome and lysosome fusion and resistance to phagocytic digestion to successfully invade host cells. In contrast, extracellular pathogens utilize toxin secretion and biofilm formation to avoid internalization by phagocytes. The complexity and diversity of bacterial virulence factors whose evolution is driven by protozoan predation, highlights the importance of protozoa in evolution of opportunistic pathogens.
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Affiliation(s)
- Shuyang Sun
- ithree Institute, University of Technology Sydney, Sydney, NSW, Australia
| | - Parisa Noorian
- ithree Institute, University of Technology Sydney, Sydney, NSW, Australia.,School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, NSW, Australia
| | - Diane McDougald
- ithree Institute, University of Technology Sydney, Sydney, NSW, Australia.,Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore, Singapore
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16
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Noorian P, Hu J, Chen Z, Kjelleberg S, Wilkins MR, Sun S, McDougald D. Pyomelanin produced by Vibrio cholerae confers resistance to predation by Acanthamoeba castellanii. FEMS Microbiol Ecol 2018; 93:4582896. [PMID: 29095994 PMCID: PMC5812506 DOI: 10.1093/femsec/fix147] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2017] [Accepted: 10/30/2017] [Indexed: 12/31/2022] Open
Abstract
Protozoan predation is one of the main environmental factors constraining bacterial growth in aquatic environments, and thus has led to the evolution of a number of defence mechanisms that protect bacteria from predation. These mechanisms may also function as virulence factors in infection of animal and human hosts. Whole transcriptome shotgun sequencing of Vibrio cholerae biofilms during predation by the amoebae, Acanthamoeba castellanii, revealed that 131 transcripts were significantly differentially regulated when compared to the non-grazed control. Differentially regulated transcripts included those involved in biosynthetic and metabolic pathways. The transcripts of genes involved in tyrosine metabolism were down-regulated in the grazed population, which indicates that the tyrosine metabolic regulon may have a role in the response of V. cholerae biofilms to A. castellanii predation. Homogentisate 1, 2-dioxygenase (HGA) is the main intermediate of the normal L-tyrosine catabolic pathway which is known to auto-oxidize, leading to the formation of the pigment, pyomelanin. Indeed, a pigmented mutant, disrupted in hmgA, was more resistant to amoebae predation than the wild type. Increased grazing resistance was correlated with increased production of pyomelanin and thus reactive oxygen species (ROS), suggesting that ROS production is a defensive mechanism used by bacterial biofilms against predation by amoebae A. castellanii.
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Affiliation(s)
- Parisa Noorian
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW 2052, Australia.,The ithree Institute, University of Technology Sydney, Sydney, NSW 2007, Australia
| | - Jie Hu
- School of Biological Sciences, Nanyang Technological University, Singapore 637551, Singapore
| | - Zhiliang Chen
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW 2052, Australia.,Systems Biology Initiative, School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW 2052, Australia
| | - Staffan Kjelleberg
- Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore 637551, Singapore
| | - Marc R Wilkins
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW 2052, Australia.,Systems Biology Initiative, School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW 2052, Australia
| | - Shuyang Sun
- The ithree Institute, University of Technology Sydney, Sydney, NSW 2007, Australia
| | - Diane McDougald
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW 2052, Australia.,The ithree Institute, University of Technology Sydney, Sydney, NSW 2007, Australia.,Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore 637551, Singapore
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17
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Oh HS, Constancias F, Ramasamy C, Tang PYP, Yee MO, Fane AG, McDougald D, Rice SA. Biofouling control in reverse osmosis by nitric oxide treatment and its impact on the bacterial community. J Memb Sci 2018. [DOI: 10.1016/j.memsci.2018.01.012] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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18
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Luo J, Lv P, Zhang J, Fane AG, McDougald D, Rice SA. Succession of biofilm communities responsible for biofouling of membrane bio-reactors (MBRs). PLoS One 2017; 12:e0179855. [PMID: 28686622 PMCID: PMC5501448 DOI: 10.1371/journal.pone.0179855] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2017] [Accepted: 06/05/2017] [Indexed: 01/26/2023] Open
Abstract
Biofilm formation is one of the main factors associated with membrane biofouling in membrane bioreactors (MBRs). As such, it is important to identify the responsible organisms to develop targeted strategies to control biofouling. This study investigated the composition and changes in the microbial communities fouling MBR membranes over time and correlated those changes with an increase in transmembrane pressure (TMP). Based on qPCR data, bacteria were the dominant taxa of the biofilm (92.9–98.4%) relative to fungi (1.5–6.9%) and archaea (0.03–0.07%). NMDS analysis indicated that during the initial stages of operation, the biofilm communities were indistinguishable from those found in the sludge. However, the biofilm community significantly diverged from the sludge over time and ultimately showed a unique biofilm profile. This suggested that there was strong selection for a group of organisms that were biofilm specialists. This pattern of succession and selection was correlated with the rapid increase in TMP, where bacteria including Rhodospirillales, Sphingomonadales and Rhizobiales dominated the biofilm at this time. While most of the identified fungal OTUs matched Candida sp., the majority of fungal communities were unclassified by 18S rRNA gene sequencing. Collectively, the data suggests that bacteria, primarily, along with fungi may play an important role in the rapid TMP increase and loss of system performance.
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Affiliation(s)
- Jinxue Luo
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
- Advanced Environmental Biotechnology Centre, Nanyang Environment and Water Research Institute, Nanyang Technological University, Singapore, Singapore
- Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, China
| | - Pengyi Lv
- School of Chemical and Environmental Engineering, China University of Mining and Technology, Beijing, China
| | - Jinsong Zhang
- Singapore Membrane Technology Centre, Nanyang Environment and Water Research Institute, Nanyang Technological University, Singapore, Singapore
| | - Anthony G. Fane
- Singapore Membrane Technology Centre, Nanyang Environment and Water Research Institute, Nanyang Technological University, Singapore, Singapore
| | - Diane McDougald
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
- Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore, Singapore
- The ithree Institute, The University of Technology Sydney, Sydney New South Wales, Sydney, Australia
| | - Scott A. Rice
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
- Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore, Singapore
- The ithree Institute, The University of Technology Sydney, Sydney New South Wales, Sydney, Australia
- Centre for Marine Bio-Innovation, School of Biological, Earth and Environmental Sciences, The University of New South Wales, Sydney, Australia
- * E-mail:
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19
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Bossa L, Kline K, McDougald D, Lee BB, Rice SA. Urinary catheter-associated microbiota change in accordance with treatment and infection status. PLoS One 2017; 12:e0177633. [PMID: 28628622 PMCID: PMC5476236 DOI: 10.1371/journal.pone.0177633] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2017] [Accepted: 05/01/2017] [Indexed: 12/25/2022] Open
Abstract
The use of long-term catheterisation to manage insensate bladders, often associated with spinal cord injury (SCI), increases the risk of microbial colonisation and infection of the urinary tract. Urinary tract infection (UTI) is typically diagnosed and treated based on the culturing of organisms from the urine, although this approach overlooks low titer, slow growing and non-traditional pathogens. Here, we present an investigation of the urinary tract microbiome in catheterised SCI individuals, using T-RFLP and metagenomic sequencing of the microbial community. We monitored three neurogenic patients over a period of 12 months, who were part of a larger study investigating the efficacy of probiotics in controlling UTIs, to determine how their urinary tract microbial community composition changed over time and in relation to probiotic treatment regimens. Bacterial biofilms adherent to urinary catheters were examined as a proxy for bladder microbes. The microbial community composition of the urinary tract differed significantly between individuals. Probiotic therapy resulted in a significant change in the microbial community associated with the catheters. The community also changed as a consequence of UTI and this shift in community composition preceded the clinical diagnosis of infection. Changes in the microbiota due to probiotic treatment or infection were transient, resolving to microbial communities similar to their pre-treatment communities, suggesting that the native community was highly resilient. Based on these results, we propose that monitoring a patient's microbial community can be used to track the health of chronically catheterized patients and thus, can be used as part of a health-status monitoring program.
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Affiliation(s)
- Laetitia Bossa
- Neuroscience Research Australia (NEURA), Sydney, New South Wales, Australia
| | - Kimberly Kline
- The Singapore Centre for Environmental Life Sciences Engineering, The School of Biological Sciences, Nanyang Technological University, Singapore
| | - Diane McDougald
- The Singapore Centre for Environmental Life Sciences Engineering, The School of Biological Sciences, Nanyang Technological University, Singapore
- The ithree Institute, The University of Technology Sydney, Sydney NSW Australia
| | - Bonsan Bonne Lee
- Neuroscience Research Australia (NEURA), Sydney, New South Wales, Australia
- Prince of Wales Hospital, Spinal Medicine Department, Randwick, NSW, Australia
| | - Scott A. Rice
- The Singapore Centre for Environmental Life Sciences Engineering, The School of Biological Sciences, Nanyang Technological University, Singapore
- The ithree Institute, The University of Technology Sydney, Sydney NSW Australia
- The Centre for Marine Bio-Innovation, The School of Biological, Earth and Environmental Sciences, The University of New South Wales, Sydney, NSW Australia
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20
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Levin RA, Beltran VH, Hill R, Kjelleberg S, McDougald D, Steinberg PD, van Oppen MJH. Sex, Scavengers, and Chaperones: Transcriptome Secrets of Divergent Symbiodinium Thermal Tolerances. Mol Biol Evol 2016; 33:3032. [PMID: 27738273 PMCID: PMC7297275 DOI: 10.1093/molbev/msw201] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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21
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Levin RA, Beltran VH, Hill R, Kjelleberg S, McDougald D, Steinberg PD, van Oppen MJH. Sex, Scavengers, and Chaperones: Transcriptome Secrets of Divergent Symbiodinium Thermal Tolerances. Mol Biol Evol 2016; 33:2201-15. [PMID: 27301593 PMCID: PMC4989115 DOI: 10.1093/molbev/msw119] [Citation(s) in RCA: 94] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Corals rely on photosynthesis by their endosymbiotic dinoflagellates (Symbiodinium spp.) to form the basis of tropical coral reefs. High sea surface temperatures driven by climate change can trigger the loss of Symbiodinium from corals (coral bleaching), leading to declines in coral health. Different putative species (genetically distinct types) as well as conspecific populations of Symbiodinium can confer differing levels of thermal tolerance to their coral host, but the genes that govern dinoflagellate thermal tolerance are unknown. Here we show physiological and transcriptional responses to heat stress by a thermo-sensitive (physiologically susceptible at 32 °C) type C1 Symbiodinium population and a thermo-tolerant (physiologically healthy at 32 °C) type C1 Symbiodinium population. After nine days at 32 °C, neither population exhibited physiological stress, but both displayed up-regulation of meiosis genes by ≥ 4-fold and enrichment of meiosis functional gene groups, which promote adaptation. After 13 days at 32 °C, the thermo-sensitive population suffered a significant decrease in photosynthetic efficiency and increase in reactive oxygen species (ROS) leakage from its cells, whereas the thermo-tolerant population showed no signs of physiological stress. Correspondingly, only the thermo-tolerant population demonstrated up-regulation of a range of ROS scavenging and molecular chaperone genes by ≥ 4-fold and enrichment of ROS scavenging and protein-folding functional gene groups. The physiological and transcriptional responses of the Symbiodinium populations to heat stress directly correlate with the bleaching susceptibilities of corals that harbored these same Symbiodinium populations. Thus, our study provides novel, foundational insights into the molecular basis of dinoflagellate thermal tolerance and coral bleaching.
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Affiliation(s)
- Rachel A Levin
- Centre for Marine Bio-Innovation, The University of New South Wales, Sydney, NSW, Australia School of Biological Earth and Environmental Sciences, The University of New South Wales, Sydney, NSW, Australia
| | - Victor H Beltran
- Australian Institute of Marine Science, Townsville MC, QLD, Australia
| | - Ross Hill
- Macquarie University, Sydney, NSW, Australia
| | - Staffan Kjelleberg
- Centre for Marine Bio-Innovation, The University of New South Wales, Sydney, NSW, Australia Singapore Centre on Environmental Life Sciences Engineering, Nanyang Technological University, Singapore
| | - Diane McDougald
- Centre for Marine Bio-Innovation, The University of New South Wales, Sydney, NSW, Australia Singapore Centre on Environmental Life Sciences Engineering, Nanyang Technological University, Singapore The iThree Institute, University of Technology Sydney, Sydney, NSW, Australia
| | - Peter D Steinberg
- Centre for Marine Bio-Innovation, The University of New South Wales, Sydney, NSW, Australia School of Biological Earth and Environmental Sciences, The University of New South Wales, Sydney, NSW, Australia Sydney Institute of Marine Science, Mosman, NSW, Australia
| | - Madeleine J H van Oppen
- Australian Institute of Marine Science, Townsville MC, QLD, Australia School of BioSciences, The University of Melbourne, Parkville, VIC, Australia
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22
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Alqarni B, Colley B, Klebensberger J, McDougald D, Rice SA. Expression stability of 13 housekeeping genes during carbon starvation of Pseudomonas aeruginosa. J Microbiol Methods 2016; 127:182-187. [PMID: 27297333 DOI: 10.1016/j.mimet.2016.06.008] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2016] [Revised: 06/09/2016] [Accepted: 06/09/2016] [Indexed: 11/29/2022]
Abstract
Quantitative real-time polymerase chain reaction (qRT-PCR) is a reliable technique for quantifying mRNA levels when normalised by a stable reference gene/s. Many putative reference genes are known to be affected by physiological stresses, such as nutrient limitation and hence may not be suitable for normalisation. In this study of Pseudomonas aeruginosa, the expression of 13 commonly used reference genes, rpoS, proC, recA, rpsL, rho, oprL, anr, tipA, nadB, fabD, ampC, algD and gyrA, were analysed for changes in expression under carbon starvation and nutrient replete conditions. The results showed that rpoS was the only stably expressed housekeeping gene during carbon starvation. In contrast, other commonly used housekeeping genes were shown to vary by as much as 10-100 fold under starvation conditions. This study has identified a suitable reference gene for qRT-PCR in P. aeruginosa during carbon starvation. The results presented here highlight the need to validate housekeeping genes under the chosen experimental conditions.
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Affiliation(s)
- Budoor Alqarni
- Centre for Marine Bio-Innovation, Earth and Environmental Sciences, The University of New South Wales, Sydney, New South Wales, Australia; The School of Biotechnology and Biomolecular Sciences, Earth and Environmental Sciences, The University of New South Wales, Sydney, New South Wales, Australia
| | - Brendan Colley
- Centre for Marine Bio-Innovation, Earth and Environmental Sciences, The University of New South Wales, Sydney, New South Wales, Australia; The School of Biotechnology and Biomolecular Sciences, Earth and Environmental Sciences, The University of New South Wales, Sydney, New South Wales, Australia
| | - Janosch Klebensberger
- University of Stuttgart, Institute of Technical Biochemistry, Allmandring 31, D-70569 Stuttgart, Germany
| | - Diane McDougald
- The ithree Institute, The University of Technology Sydney, Australia; Singapore Centre for Environmental Life Sciences Engineering and the School of Biological Sciences, Nanyang Technological University, Singapore
| | - Scott A Rice
- Centre for Marine Bio-Innovation, Earth and Environmental Sciences, The University of New South Wales, Sydney, New South Wales, Australia; The School of Biological, Earth and Environmental Sciences, The University of New South Wales, Sydney, New South Wales, Australia; Singapore Centre for Environmental Life Sciences Engineering and the School of Biological Sciences, Nanyang Technological University, Singapore.
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23
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Chavez-Dozal AA, Nourabadi N, Erken M, McDougald D, Nishiguchi MK. Comparative analysis of quantitative methodologies for Vibrionaceae biofilms. Folia Microbiol (Praha) 2016; 61:449-453. [PMID: 27009592 DOI: 10.1007/s12223-016-0456-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2015] [Accepted: 03/09/2016] [Indexed: 11/29/2022]
Abstract
Multiple symbiotic and free-living Vibrio spp. grow as a form of microbial community known as a biofilm. In the laboratory, methods to quantify Vibrio biofilm mass include crystal violet staining, direct colony-forming unit (CFU) counting, dry biofilm cell mass measurement, and observation of development of wrinkled colonies. Another approach for bacterial biofilms also involves the use of tetrazolium (XTT) assays (used widely in studies of fungi) that are an appropriate measure of metabolic activity and vitality of cells within the biofilm matrix. This study systematically tested five techniques, among which the XTT assay and wrinkled colony measurement provided the most reproducible, accurate, and efficient methods for the quantitative estimation of Vibrionaceae biofilms.
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Affiliation(s)
- Alba A Chavez-Dozal
- Section of Infectious Diseases, New Mexico Veterans Healthcare System, Albuquerque, NM, 87108, USA.,Division of Infectious Diseases, University of New Mexico Health Science Center, Albuquerque, NM, 87131, USA
| | - Neda Nourabadi
- Department of Biology, New Mexico State University, Box 30001, MSC 3AF, Las Cruces, NM, 88003-8001, USA
| | - Martina Erken
- Centre for Marine Biofouling and Bio-Innovation, School of Biotechnology and Biomolecular Sciences, University of South Wales, Sydney, NSW, 2052, Australia
| | - Diane McDougald
- ithree Institute, Faculty of Science, University of Technology, Sydney, Broadway, Sydney, NSW, 2007, Australia.,Singapore Centre on Environmental Life Sciences Engineering, School of Biological Sciences, Nanyang Technological University, Singapore, 637551, Singapore
| | - Michele K Nishiguchi
- Department of Biology, New Mexico State University, Box 30001, MSC 3AF, Las Cruces, NM, 88003-8001, USA.
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24
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Luo J, Zhang J, Barnes RJ, Tan X, McDougald D, Fane AG, Zhuang G, Kjelleberg S, Cohen Y, Rice SA. The application of nitric oxide to control biofouling of membrane bioreactors. Microb Biotechnol 2015; 8:549-60. [PMID: 25752591 PMCID: PMC4408187 DOI: 10.1111/1751-7915.12261] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2014] [Revised: 10/27/2014] [Accepted: 12/13/2014] [Indexed: 12/13/2022] Open
Abstract
A novel strategy to control membrane bioreactor (MBR) biofouling using the nitric oxide (NO) donor compound PROLI NONOate was examined. When the biofilm was pre-established on membranes at transmembrane pressure (TMP) of 88–90 kPa, backwashing of the membrane module with 80 μM PROLI NONOate for 45 min once daily for 37 days reduced the fouling resistance (Rf) by 56%. Similarly, a daily, 1 h exposure of the membrane to 80 μM PROLI NONOate from the commencement of MBR operation for 85 days resulted in reduction of the TMP and Rf by 32.3% and 28.2%. The microbial community in the control MBR was observed to change from days 71 to 85, which correlates with the rapid TMP increase. Interestingly, NO-treated biofilms at 85 days had a higher similarity with the control biofilms at 71 days relative to the control biofilms at 85 days, indicating that the NO treatment delayed the development of biofilm bacterial community. Despite this difference, sequence analysis indicated that NO treatment did not result in a significant shift in the dominant fouling species. Confocal microscopy revealed that the biomass of biopolymers and microorganisms in biofilms were all reduced on the PROLI NONOate-treated membranes, where there were reductions of 37.7% for proteins and 66.7% for microbial cells, which correlates with the reduction in TMP. These results suggest that NO treatment could be a promising strategy to control biofouling in MBRs.
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Affiliation(s)
- Jinxue Luo
- Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, China; School of Biological Sciences, 60 Nanyang Drive, SBS-01N-27, Singapore, 637551; Advanced Environmental Biotechnology Centre, Nanyang Technological University, Singapore
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25
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Akhondi E, Wu B, Sun S, Marxer B, Lim W, Gu J, Liu L, Burkhardt M, McDougald D, Pronk W, Fane AG. Gravity-driven membrane filtration as pretreatment for seawater reverse osmosis: linking biofouling layer morphology with flux stabilization. Water Res 2015; 70:158-73. [PMID: 25528546 DOI: 10.1016/j.watres.2014.12.001] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2014] [Revised: 11/27/2014] [Accepted: 12/01/2014] [Indexed: 05/22/2023]
Abstract
In this study gravity-driven membrane (GDM) ultrafiltration is investigated for the pretreatment of seawater before reverse osmosis (RO). The impacts of temperature (21 ± 1 and 29 ± 1 °C) and hydrostatic pressure (40 and 100 mbar) on dynamic flux development and biofouling layer structure were studied. The data suggested pore constriction fouling was predominant at the early stage of filtration, during which the hydrostatic pressure and temperature had negligible effects on permeate flux. With extended filtration time, cake layer fouling played a major role, during which higher hydrostatic pressure and temperature improved permeate flux. The permeate flux stabilized in a range of 3.6 L/m(2) h (21 ± 1 °C, 40 mbar) to 7.3 L/m(2) h (29 ± 1 °C, 100 mbar) after slight fluctuations and remained constant for the duration of the experiments (almost 3 months). An increase in biofouling layer thickness and a variable biofouling layer structure were observed over time by optical coherence tomography and confocal laser scanning microscopy. The presence of eukaryotic organisms in the biofouling layer was observed by light microscopy and the microbial community structure of the biofouling layer was analyzed by sequences of 16S rRNA genes. The magnitude of permeate flux was associated with the combined effect of the biofouling layer thickness and structure. Changes in the biofouling layer structure were attributed to (1) the movement and predation behaviour of the eukaryotic organisms which increased the heterogeneous nature of the biofouling layer; (2) the bacterial debris generated by eukaryotic predation activity which reduced porosity; (3) significant shifts of the dominant bacterial species over time that may have influenced the biofouling layer structure. As expected, most of the particles and colloids in the feed seawater were removed by the GDM process, which led to a lower RO fouling potential. However, the dissolved organic carbon in the permeate was not be reduced, possibly because some microbial species (e.g. algae) could convert CO2 into organic substances. To further improve the removal efficiency of the organic carbon, combining carrier biofilm processes with a submerged GDM filtration system is proposed.
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Affiliation(s)
- Ebrahim Akhondi
- Singapore Membrane Technology Centre, Nanyang Environment and Water Research Institute, Nanyang Technological University, 1 Cleantech Loop, CleanTech One #06-08, Singapore 637141, Singapore
| | - Bing Wu
- Singapore Membrane Technology Centre, Nanyang Environment and Water Research Institute, Nanyang Technological University, 1 Cleantech Loop, CleanTech One #06-08, Singapore 637141, Singapore.
| | - Shuyang Sun
- Singapore Centre on Environmental Life Sciences Engineering, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551, Singapore; Centre for Marine Bio-Innovation, The University of New South Wales, Sydney, NSW 2052, Australia
| | - Brigit Marxer
- Institute of Environmental and Process Engineering, HSR University of Applied Sciences Rapperswil, Oberseestrasse 10, 8640 Rapperswil, Switzerland
| | - Weikang Lim
- Singapore Membrane Technology Centre, Nanyang Environment and Water Research Institute, Nanyang Technological University, 1 Cleantech Loop, CleanTech One #06-08, Singapore 637141, Singapore
| | - Jun Gu
- School of Electrical & Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore
| | - Linbo Liu
- School of Electrical & Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore
| | - Michael Burkhardt
- Institute of Environmental and Process Engineering, HSR University of Applied Sciences Rapperswil, Oberseestrasse 10, 8640 Rapperswil, Switzerland
| | - Diane McDougald
- Singapore Centre on Environmental Life Sciences Engineering, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551, Singapore; Centre for Marine Bio-Innovation, The University of New South Wales, Sydney, NSW 2052, Australia
| | - Wouter Pronk
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, Ueberlandstrasse 133, 8600 Duebendorf, Switzerland
| | - Anthony G Fane
- Singapore Membrane Technology Centre, Nanyang Environment and Water Research Institute, Nanyang Technological University, 1 Cleantech Loop, CleanTech One #06-08, Singapore 637141, Singapore; School of Civil and Environmental Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore
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26
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Luo J, Zhang J, Tan X, McDougald D, Zhuang G, Fane AG, Kjelleberg S, Cohen Y, Rice SA. Characterization of the archaeal community fouling a membrane bioreactor. J Environ Sci (China) 2015; 29:115-123. [PMID: 25766019 DOI: 10.1016/j.jes.2014.07.025] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2014] [Revised: 07/14/2014] [Accepted: 07/19/2014] [Indexed: 06/04/2023]
Abstract
Biofilm formation, one of the primary causes of biofouling, results in reduced membrane flux or increased transmembrane pressure and thus represents a major impediment to the wider implementation of membrane bioreactor (MBR) technologies for water purification. Most studies have focused on the role of bacteria in membrane fouling as they are the most dominant and best studied organisms present in the MBR. In contrast, there is limited information on the role of the archaeal community in biofilm formation in MBRs. This study investigated the composition of the archaeal community during the process of biofouling in an MBR. The archaeal community was observed to have lower richness and diversity in the biofilm than the sludge during the establishment of biofilms at low transmembrane pressure (TMP). Clustering of the communities based on the Bray-Curtis similarity matrix indicated that a subset of the sludge archaeal community formed the initial biofilms. The archaeal community in the biofilm was mainly composed of Thermoprotei, Thermoplasmata, Thermococci, Methanopyri, Methanomicrobia and Halobacteria. Among them, the Thermoprotei and Thermoplasmata were present at higher relative proportions in the biofilms than they were in the sludge. Additionally, the Thermoprotei, Thermoplasmata and Thermococci were the dominant organisms detected in the initial biofilms at low TMP, while as the TMP increased, the Methanopyri, Methanomicrobia, Aciduliprofundum and Halobacteria were present at higher abundances in the biofilms at high TMP.
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Affiliation(s)
- Jinxue Luo
- Key Laboratory of Environmental Biotechnology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; School of Biological Sciences, Nanyang Technological University, Singapore 639798, Singapore; Advanced Environmental Biotechnology Centre, Nanyang Environment and Water Research Institute, Nanyang Technological University, 639798, Singapore.
| | - Jinsong Zhang
- Singapore Membrane Technology Centre, Nanyang Environment and Water Research Institute, Nanyang Technological University, 639798, Singapore
| | - Xiaohui Tan
- Advanced Environmental Biotechnology Centre, Nanyang Environment and Water Research Institute, Nanyang Technological University, 639798, Singapore
| | - Diane McDougald
- School of Biological Sciences, Nanyang Technological University, Singapore 639798, Singapore; Centre for Marine Bio-Innovation, School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, NSW 2052, Australia; Singapore Centre on Environmental Life Sciences Engineering, Nanyang Technological University, 639798, Singapore
| | - Guoqiang Zhuang
- Key Laboratory of Environmental Biotechnology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
| | - Anthony G Fane
- Singapore Membrane Technology Centre, Nanyang Environment and Water Research Institute, Nanyang Technological University, 639798, Singapore
| | - Staffan Kjelleberg
- School of Biological Sciences, Nanyang Technological University, Singapore 639798, Singapore; Centre for Marine Bio-Innovation, School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, NSW 2052, Australia; Singapore Centre on Environmental Life Sciences Engineering, Nanyang Technological University, 639798, Singapore
| | - Yehuda Cohen
- School of Biological Sciences, Nanyang Technological University, Singapore 639798, Singapore; Singapore Centre on Environmental Life Sciences Engineering, Nanyang Technological University, 639798, Singapore
| | - Scott A Rice
- School of Biological Sciences, Nanyang Technological University, Singapore 639798, Singapore; Centre for Marine Bio-Innovation, School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, NSW 2052, Australia; Singapore Centre on Environmental Life Sciences Engineering, Nanyang Technological University, 639798, Singapore.
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Zhang Q, Shuwen G, Zhang J, Fane AG, Kjelleberg S, Rice SA, McDougald D. Analysis of microbial community composition in a lab-scale membrane distillation bioreactor. J Appl Microbiol 2015; 118:940-53. [PMID: 25604265 PMCID: PMC4409088 DOI: 10.1111/jam.12759] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2014] [Revised: 01/01/2015] [Accepted: 01/11/2015] [Indexed: 12/23/2022]
Abstract
Aims Membrane distillation bioreactors (MDBR) have potential for industrial applications where wastewater is hot or waste heat is available, but the role of micro-organisms in MDBRs has never been determined, and thus was the purpose of this study. Methods and Results Microbial communities were characterized by bacterial and archaeal 16S and eukaryotic 18S rRNA gene tag-encoded pyrosequencing of DNA obtained from sludge. Taxonomy-independent analysis revealed that bacterial communities had a relatively low richness and diversity, and community composition strongly correlated with conductivity, total nitrogen and bound extracellular polymeric substances (EPS). Taxonomy-dependent analysis revealed that Rubrobacter and Caldalkalibacillus were abundant members of the bacterial community, but no archaea were detected. Eukaryotic communities had a relatively high richness and diversity, and both changes in community composition and abundance of the dominant genus, Candida, correlated with bound EPS. Conclusions Thermophilic MDBR communities were comprised of a low diversity bacterial community and a highly diverse eukaryotic community with no archea detected. Communities exhibited low resilience to changes in operational parameters. Specifically, retenatate nutrient composition and concentration was strongly correlated with the dominant species. Significance and Impact of the Study This study provides an understanding of microbial community diversity in an MDBR, which is fundamental to the optimization of reactor performance.
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Affiliation(s)
- Q Zhang
- Advanced Environmental Biotechnology Centre, Nanyang Environment and Water Research Institute, Nanyang Technological University, Singapore City, Singapore; School of Biological Sciences, Nanyang Technological University, Singapore City, Singapore
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28
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Mai-Prochnow A, Hui JGK, Kjelleberg S, Rakonjac J, McDougald D, Rice SA. 'Big things in small packages: the genetics of filamentous phage and effects on fitness of their host'. FEMS Microbiol Rev 2015; 39:465-87. [PMID: 25670735 DOI: 10.1093/femsre/fuu007] [Citation(s) in RCA: 103] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2014] [Accepted: 12/17/2014] [Indexed: 01/01/2023] Open
Abstract
This review synthesizes recent and past observations on filamentous phages and describes how these phages contribute to host phentoypes. For example, the CTXφ phage of Vibrio cholerae encodes the cholera toxin genes, responsible for causing the epidemic disease, cholera. The CTXφ phage can transduce non-toxigenic strains, converting them into toxigenic strains, contributing to the emergence of new pathogenic strains. Other effects of filamentous phage include horizontal gene transfer, biofilm development, motility, metal resistance and the formation of host morphotypic variants, important for the biofilm stress resistance. These phages infect a wide range of Gram-negative bacteria, including deep-sea, pressure-adapted bacteria. Many filamentous phages integrate into the host genome as prophage. In some cases, filamentous phages encode their own integrase genes to facilitate this process, while others rely on host-encoded genes. These differences are mediated by different sets of 'core' and 'accessory' genes, with the latter group accounting for some of the mechanisms that alter the host behaviours in unique ways. It is increasingly clear that despite their relatively small genomes, these phages exert signficant influence on their hosts and ultimately alter the fitness and other behaviours of their hosts.
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Affiliation(s)
- Anne Mai-Prochnow
- The Centre for Marine Bio-Innovation and the School of Biotechnology and Biomolecular Sciences, the University of New South Wales, Sydney NSW 2052, Australia
| | - Janice Gee Kay Hui
- The Centre for Marine Bio-Innovation and the School of Biotechnology and Biomolecular Sciences, the University of New South Wales, Sydney NSW 2052, Australia
| | - Staffan Kjelleberg
- The Centre for Marine Bio-Innovation and the School of Biotechnology and Biomolecular Sciences, the University of New South Wales, Sydney NSW 2052, Australia The Singapore Centre on Environmental Life Sciences Engineering and the School of Biological Sciences, Nanyang Technological University, 637551, Singapore
| | - Jasna Rakonjac
- Institute of Fundamental Sciences, Massey University, Palmerston North 4442, New Zealand
| | - Diane McDougald
- The Centre for Marine Bio-Innovation and the School of Biotechnology and Biomolecular Sciences, the University of New South Wales, Sydney NSW 2052, Australia The Singapore Centre on Environmental Life Sciences Engineering and the School of Biological Sciences, Nanyang Technological University, 637551, Singapore
| | - Scott A Rice
- The Centre for Marine Bio-Innovation and the School of Biotechnology and Biomolecular Sciences, the University of New South Wales, Sydney NSW 2052, Australia The Singapore Centre on Environmental Life Sciences Engineering and the School of Biological Sciences, Nanyang Technological University, 637551, Singapore
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29
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Mazel D, Colwell R, Klose K, Oliver J, Crumlish M, McDougald D, Bland MJ, Austin B. VIBRIO 2014 meeting report. Res Microbiol 2014; 165:857-64. [PMID: 25463383 DOI: 10.1016/j.resmic.2014.10.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2014] [Revised: 10/15/2014] [Accepted: 10/15/2014] [Indexed: 11/16/2022]
Affiliation(s)
- Didier Mazel
- Unité Plasticité du Génome bactérien and CNRS UMR 3525, Département de Génomes et Génétique, Institut Pasteur, Paris, France.
| | - Rita Colwell
- Maryland Pathogen Research Institute and Center of Bioinformatics and Computational Biology, University of Maryland, College Park, MD 20742, USA
| | - Karl Klose
- Department of Biology, University of Texas San Antonio, San Antonio, TX 78249, USA
| | - James Oliver
- Department of Biology, University North Carolina at Charlotte, Charlotte, NC 28223, USA
| | - Mags Crumlish
- Institute of Aquaculture, University of Stirling, Stirling FK9 4LA, UK
| | - Diane McDougald
- Centre for Marine Bio-Innovation, School of Biotechnology and Biomolecular Science, The University of New South Wales, Sydney 2052, Australia
| | - Michael J Bland
- Unité Plasticité du Génome bactérien and CNRS UMR 3525, Département de Génomes et Génétique, Institut Pasteur, Paris, France
| | - Brian Austin
- Institute of Aquaculture, University of Stirling, Stirling FK9 4LA, UK
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30
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Hui JGK, Mai-Prochnow A, Kjelleberg S, McDougald D, Rice SA. Environmental cues and genes involved in establishment of the superinfective Pf4 phage of Pseudomonas aeruginosa. Front Microbiol 2014; 5:654. [PMID: 25520708 PMCID: PMC4251444 DOI: 10.3389/fmicb.2014.00654] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2014] [Accepted: 11/13/2014] [Indexed: 11/21/2022] Open
Abstract
Biofilm development in Pseudomonas aeruginosa is in part dependent on a filamentous phage, Pf4, which contributes to biofilm maturation, cell death, dispersal and variant formation, e.g., small colony variants (SCVs). These biofilm phenotypes correlate with the conversion of the Pf4 phage into a superinfection (SI) variant that reinfects and kills the prophage carrying host, in contrast to other filamentous phage that normally replicate without killing their host. Here we have investigated the physiological cues and genes that may be responsible for this conversion. Flow through biofilms typically developed SI phage approximately days 4 or 5 of development and corresponded with dispersal. Starvation for carbon or nitrogen did not lead to the development of SI phage. In contrast, exposure of the biofilm to nitric oxide, H2O2 or the DNA damaging agent, mitomycin C, showed a trend of increased numbers of SI phage, suggesting that reactive oxygen or nitrogen species (RONS) played a role in the formation of SI phage. In support of this, mutation of oxyR, the major oxidative stress regulator in P. aeruginosa, resulted in higher level of and earlier superinfection compared to the wild-type (WT). Similarly, inactivation of mutS, a DNA mismatch repair gene, resulted in the early appearance of the SI phage and this was four log higher than the WT. In contrast, loss of recA, which is important for DNA repair and the SOS response, also resulted in a delayed and decreased production of SI phage. Treatments or mutations that increased superinfection also correlated with an increase in the production of morphotypic variants. The results suggest that the accumulation of RONS by the biofilm may result in DNA lesions in the Pf4 phage, leading to the formation of SI phage, which subsequently selects for morphotypic variants, such as SCVs.
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Affiliation(s)
- Janice G K Hui
- The Centre for Marine Bio-Innovation and the School of Biotechnology and Biomolecular Sciences, The University of New South Wales Sydney, NSW, Australia
| | - Anne Mai-Prochnow
- The Centre for Marine Bio-Innovation and the School of Biotechnology and Biomolecular Sciences, The University of New South Wales Sydney, NSW, Australia
| | - Staffan Kjelleberg
- The Centre for Marine Bio-Innovation and the School of Biotechnology and Biomolecular Sciences, The University of New South Wales Sydney, NSW, Australia ; The Singapore Centre on Environmental Life Sciences Engineering and The School of Biological Sciences, Nanyang Technological University Singapore, Republic of Singapore
| | - Diane McDougald
- The Centre for Marine Bio-Innovation and the School of Biotechnology and Biomolecular Sciences, The University of New South Wales Sydney, NSW, Australia ; The Singapore Centre on Environmental Life Sciences Engineering and The School of Biological Sciences, Nanyang Technological University Singapore, Republic of Singapore
| | - Scott A Rice
- The Centre for Marine Bio-Innovation and the School of Biotechnology and Biomolecular Sciences, The University of New South Wales Sydney, NSW, Australia ; The Singapore Centre on Environmental Life Sciences Engineering and The School of Biological Sciences, Nanyang Technological University Singapore, Republic of Singapore
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31
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Luo J, Zhang J, Tan X, McDougald D, Zhuang G, Fane AG, Kjelleberg S, Cohen Y, Rice SA. The correlation between biofilm biopolymer composition and membrane fouling in submerged membrane bioreactors. Biofouling 2014; 30:1093-1110. [PMID: 25367774 DOI: 10.1080/08927014.2014.971238] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Biofouling, the combined effect of microorganism and biopolymer accumulation, significantly reduces the process efficiency of membrane bioreactors (MBRs). Here, four biofilm components, alpha-polysaccharides, beta-polysaccharides, proteins and microorganisms, were quantified in MBRs. The biomass of each component was positively correlated with the transmembrane pressure increase in MBRs. Proteins were the most abundant biopolymer in biofilms and showed the fastest rate of increase. The spatial distribution and co-localization analysis of the biofouling components indicated at least 60% of the extracellular polysaccharide (EPS) components were associated with the microbial cells when the transmembrane pressure (TMP) entered the jump phase, suggesting that the EPS components were either secreted by the biofilm cells or that the deposition of these components facilitated biofilm formation. It is suggested that biofilm formation and the accumulation of EPS are intrinsically coupled, resulting in biofouling and loss of system performance. Therefore, strategies that control biofilm formation on membranes may result in a significant improvement of MBR performance.
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Affiliation(s)
- Jinxue Luo
- a Research Center for Eco-Environmental Sciences , Chinese Academy of Sciences , Beijing , PR China
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32
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Lauro FM, Senstius SJ, Cullen J, Neches R, Jensen RM, Brown MV, Darling AE, Givskov M, McDougald D, Hoeke R, Ostrowski M, Philip GK, Paulsen IT, Grzymski JJ. The common oceanographer: crowdsourcing the collection of oceanographic data. PLoS Biol 2014; 12:e1001947. [PMID: 25203659 PMCID: PMC4159111 DOI: 10.1371/journal.pbio.1001947] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- Federico M. Lauro
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, New South Wales, Australia
- Singapore Centre on Environmental Life Sciences Engineering (SCELSE), Nanyang Technological University, Singapore
- * E-mail: (FML); (JJG)
| | | | - Jay Cullen
- School of Earth and Ocean Sciences, University of Victoria, Victoria, British Columbia, Canada
| | - Russell Neches
- Genome Center, University of California, Davis, California, United States of America
| | - Rachelle M. Jensen
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, New South Wales, Australia
| | - Mark V. Brown
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, New South Wales, Australia
| | - Aaron E. Darling
- The ithree institute, University of Technology Sydney, Ultimo, New South Wales, Australia
| | - Michael Givskov
- Singapore Centre on Environmental Life Sciences Engineering (SCELSE), Nanyang Technological University, Singapore
- Costerton Biofilm Center, Department of International Health, Immunology, and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Diane McDougald
- Singapore Centre on Environmental Life Sciences Engineering (SCELSE), Nanyang Technological University, Singapore
- Centre for Marine Bio-Innovation, University of New South Wales, Sydney, New South Wales, Australia
| | - Ron Hoeke
- Centre for Australian Climate and Weather Research, CSIRO, Aspendale, Victoria, Australia
| | - Martin Ostrowski
- Department of Chemistry and Biomolecular Sciences, Macquarie University, Sydney, New South Wales, Australia
| | - Gayle K. Philip
- VLSCI Life Sciences Computation Centre, University of Melbourne, Melbourne, Victoria, Australia
| | - Ian T. Paulsen
- Department of Chemistry and Biomolecular Sciences, Macquarie University, Sydney, New South Wales, Australia
| | - Joseph J. Grzymski
- Division of Earth and Ecosystem Sciences, Desert Research Institute, Reno, Nevada, United States of America
- * E-mail: (FML); (JJG)
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Zhang Q, Jie YW, Loong WLC, Zhang J, Fane AG, Kjelleberg S, Rice SA, McDougald D. Characterization of biofouling in a lab-scale forward osmosis membrane bioreactor (FOMBR). Water Res 2014; 58:141-151. [PMID: 24751548 DOI: 10.1016/j.watres.2014.03.052] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2013] [Revised: 03/13/2014] [Accepted: 03/18/2014] [Indexed: 06/03/2023]
Abstract
Forward osmosis membrane bioreactors (FOMBR) provide high quality permeate, however the propensity for membrane biofouling in FOMBRs is unknown. Here, FOMBRs were operated under high and low aeration and the membrane-associated biofilms were characterized by confocal laser scanning microscopy (CLSM) and rRNA gene-tagged pyrosequencing. CLSM images revealed that there was little biofilm formed under high aeration, while thick biofilms were observed on the membranes operated under low aeration. The diversity and richness of bacterial and archaeal communities as assessed by pyrosequencing varied under high and low aeration. The composition of the bacterial suspended sludge communities and the sessile biomass on the membrane surface, as assessed by non-metric multidimensional scaling, was significantly different under high aeration, but was more similar under low aeration. SIMPER analysis indicated that Pseudomonas, Aeromonas and Fluviicola preferentially attached to the membrane. The results presented here provide a comprehensive understanding of membrane biofouling in FOMBRs, which is essential for the development of effective control strategies.
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Affiliation(s)
- Qiaoyun Zhang
- Advanced Environmental Biotechnology Centre, Nanyang Environment and Water Research Institute, Singapore
| | - Yap Wei Jie
- Singapore Membrane Technology Centre, Nanyang Environment and Water Research Institute, Singapore
| | - Winson Lay Chee Loong
- Singapore Membrane Technology Centre, Nanyang Environment and Water Research Institute, Singapore
| | - Jinsong Zhang
- Singapore Membrane Technology Centre, Nanyang Environment and Water Research Institute, Singapore
| | - Anthony G Fane
- Singapore Membrane Technology Centre, Nanyang Environment and Water Research Institute, Singapore
| | - Staffan Kjelleberg
- Centre for Marine Bio-Innovation, School of Biotechnology and Biomolecular Science, University of New South Wales, Sydney, Australia; Singapore Centre on Environmental Life Sciences Engineering, Nanyang Technological University, Singapore; School of Biological Sciences, Nanyang Technological University, Singapore
| | - Scott A Rice
- Centre for Marine Bio-Innovation, School of Biotechnology and Biomolecular Science, University of New South Wales, Sydney, Australia; Singapore Centre on Environmental Life Sciences Engineering, Nanyang Technological University, Singapore; School of Biological Sciences, Nanyang Technological University, Singapore
| | - Diane McDougald
- Advanced Environmental Biotechnology Centre, Nanyang Environment and Water Research Institute, Singapore; Centre for Marine Bio-Innovation, School of Biotechnology and Biomolecular Science, University of New South Wales, Sydney, Australia; School of Biological Sciences, Nanyang Technological University, Singapore.
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34
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Ling GC, Low MH, Erken M, Longford S, Nielsen S, Poole AJ, Steinberg P, McDougald D, Kjelleberg S. Micro-fabricated polydimethyl siloxane (PDMS) surfaces regulate the development of marine microbial biofilm communities. Biofouling 2014; 30:323-335. [PMID: 24558964 DOI: 10.1080/08927014.2013.872778] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
This study explored an antifouling (AF) concept based on deployment of microfabricated polydimethyl siloxane (PDMS) surfaces with 1-10 μm periodicity corrugated topographies in temperate marine waters. The effect of the surfaces on the development of microbial biofilms over 28 days and during different seasons, including both summer and winter, was examined using confocal laser scanning microscopy (CLSM) as well as terminal restriction fragment (T-RF) analysis for phylogenetic fingerprinting. The microscale topography significantly impacted biofilm development by altering the attachment pattern and reducing microcolony formation on the 1, 2 and 4 μm PDMS surfaces. Also, field deployments over 28 days showed a significant reduction in biovolume on the 4 and 10 μm PDMS surfaces despite altered environmental conditions. The microfabricated PDMS surfaces further significantly impacted on the community composition of the biofilms, as revealed by changes in T-RF profiles, at different stages of development. Moreover, altered biofilm resistance was demonstrated by exposing pre-established biofilms on 10 μm micro-fabricated surfaces to enhanced flagellate predation by a heterotrophic protist, Rhynchomonas nasuta. Pronounced changes in the overall marine microbial biofilm development as well as community composition warrant exploring substratum modification for marine AF applications.
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Affiliation(s)
- Gee Chong Ling
- a School of Biotechnology and Biomolecular Sciences and Centre for Marine Bio-Innovation , University of New South Wales , Sydney , NSW 2052 , Australia
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35
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Lutz C, Erken M, Noorian P, Sun S, McDougald D. Environmental reservoirs and mechanisms of persistence of Vibrio cholerae. Front Microbiol 2013; 4:375. [PMID: 24379807 PMCID: PMC3863721 DOI: 10.3389/fmicb.2013.00375] [Citation(s) in RCA: 153] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2013] [Accepted: 11/21/2013] [Indexed: 12/23/2022] Open
Abstract
It is now well accepted that Vibrio cholerae, the causative agent of the water-borne disease cholera, is acquired from environmental sources where it persists between outbreaks of the disease. Recent advances in molecular technology have demonstrated that this bacterium can be detected in areas where it has not previously been isolated, indicating a much broader, global distribution of this bacterium outside of endemic regions. The environmental persistence of V. cholerae in the aquatic environment can be attributed to multiple intra- and interspecific strategies such as responsive gene regulation and biofilm formation on biotic and abiotic surfaces, as well as interactions with a multitude of other organisms. This review will discuss some of the mechanisms that enable the persistence of this bacterium in the environment. In particular, we will discuss how V. cholerae can survive stressors such as starvation, temperature, and salinity fluctuations as well as how the organism persists under constant predation by heterotrophic protists.
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Affiliation(s)
- Carla Lutz
- Centre for Marine Bio-Innovation, School of Biotechnology and Biomolecular Science, University of New South Wales Sydney, NSW, Australia
| | - Martina Erken
- Centre for Marine Bio-Innovation, School of Biotechnology and Biomolecular Science, University of New South Wales Sydney, NSW, Australia ; Advanced Environmental Biotechnology Centre, Nanyang Environment and Water Research Institute, School of Biological Sciences, Nanyang Technological University Singapore, Singapore
| | - Parisa Noorian
- Centre for Marine Bio-Innovation, School of Biotechnology and Biomolecular Science, University of New South Wales Sydney, NSW, Australia
| | - Shuyang Sun
- The Singapore Centre on Environmental Life Sciences Engineering, Nanyang Technological University Singapore, Singapore
| | - Diane McDougald
- Centre for Marine Bio-Innovation, School of Biotechnology and Biomolecular Science, University of New South Wales Sydney, NSW, Australia ; Advanced Environmental Biotechnology Centre, Nanyang Environment and Water Research Institute, School of Biological Sciences, Nanyang Technological University Singapore, Singapore
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Erken M, Lutz C, McDougald D. The rise of pathogens: predation as a factor driving the evolution of human pathogens in the environment. Microb Ecol 2013; 65:860-8. [PMID: 23354181 PMCID: PMC3637895 DOI: 10.1007/s00248-013-0189-0] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2012] [Accepted: 01/14/2013] [Indexed: 05/08/2023]
Abstract
Bacteria in the environment must survive predation from bacteriophage, heterotrophic protists, and predatory bacteria. This selective pressure has resulted in the evolution of a variety of defense mechanisms, which can also function as virulence factors. Here we discuss the potential dual function of some of the mechanisms, which protect against heterotrophic protists, and how predation pressure leads to the evolution of pathogenicity. This is in accordance with the coincidental evolution hypothesis, which suggests that virulence factors arose as a response to other selective pressures, for example, predation rather than for virulence per se. In this review we discuss some of those environmental factors that may be associated with the rise of pathogens in the marine environment. In particular, we will discuss the role of heterotrophic protists in the evolution of virulence factors in marine bacteria. Finally, we will discuss the implications for expansion of current pathogens and emergence of new pathogens.
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Affiliation(s)
- Martina Erken
- Centre for Marine Bio-Innovation, School of Biotechnology and Biomolecular Science, University of New South Wales, Sydney, New South Wales 2052 Australia
| | - Carla Lutz
- Centre for Marine Bio-Innovation, School of Biotechnology and Biomolecular Science, University of New South Wales, Sydney, New South Wales 2052 Australia
| | - Diane McDougald
- Centre for Marine Bio-Innovation, School of Biotechnology and Biomolecular Science, University of New South Wales, Sydney, New South Wales 2052 Australia
- Advanced Environmental Biotechnology Centre, Nanyang Environment and Water Research Institute, School of Biological Sciences, Nanyang Technological University, Nanyang Avenue, Singapore, 637551 Singapore
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Sun S, Kjelleberg S, McDougald D. Relative contributions of Vibrio polysaccharide and quorum sensing to the resistance of Vibrio cholerae to predation by heterotrophic protists. PLoS One 2013; 8:e56338. [PMID: 23441178 PMCID: PMC3575383 DOI: 10.1371/journal.pone.0056338] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2012] [Accepted: 01/08/2013] [Indexed: 12/04/2022] Open
Abstract
Protozoan grazing is a major mortality factor faced by bacteria in the environment. Vibrio cholerae, the causative agent of the disease cholera, is a natural inhabitant of aquatic ecosystems, and its survival depends on its ability to respond to stresses, such as predation by heterotrophic protists. Previous results show that grazing pressure induces biofilm formation and enhances a smooth to rugose morphotypic shift, due to increased expression of Vibrio polysaccharide (VPS). In addition to negatively controlling vps genes, the global quorum sensing (QS) regulator, HapR, plays a role in grazing resistance as the ΔhapR strain is efficiently consumed while the wild type (WT) is not. Here, the relative and combined contributions of VPS and QS to grazing resistance were investigated by exposing VPS and HapR mutants and double mutants in VPS and HapR encoding genes at different phases of biofilm development to amoeboid and flagellate grazers. Data show that the WT biofilms were grazing resistant, the VPS mutants were less resistant than the WT strain, but more resistant than the QS mutant strain, and that QS contributes to grazing resistance mainly in mature biofilms. In addition, grazing effects on biofilms of mixed WT and QS mutant strains were investigated. The competitive fitness of each strain in mixed biofilms was determined by CFU and microscopy. Data show that protozoa selectively grazed the QS mutant in mixed biofilms, resulting in changes in the composition of the mixed community. A small proportion of QS mutant cells which comprised 4% of the mixed biofilm biovolume were embedded in grazing resistant WT microcolonies and shielded from predation, indicating the existence of associational protection in mixed biofilms.
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Affiliation(s)
- Shuyang Sun
- Centre for Marine Bio-Innovation, School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, New South Wales, Australia
| | - Staffan Kjelleberg
- Centre for Marine Bio-Innovation, School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, New South Wales, Australia
- Singapore Centre on Environmental Life Sciences Engineering, Nanyang Technological University, Singapore, Singapore
| | - Diane McDougald
- Centre for Marine Bio-Innovation, School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, New South Wales, Australia
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
- Advanced Environmental Biotechnology Centre, Nanyang Environment and Water Institute, Nanyang Technological University, Singapore, Singapore
- * E-mail:
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Barnes RJ, Bandi RR, Wong WS, Barraud N, McDougald D, Fane A, Kjelleberg S, Rice SA. Optimal dosing regimen of nitric oxide donor compounds for the reduction of Pseudomonas aeruginosa biofilm and isolates from wastewater membranes. Biofouling 2013; 29:203-212. [PMID: 23368407 DOI: 10.1080/08927014.2012.760069] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Membrane fouling by bacterial biofilms remains a key challenge for membrane-based water purification systems. Here, the optimal biofilm dispersal potential of three nitric oxide (NO) donor compounds, viz. sodium nitroprusside, 6-(2-hydroxy-1-methyl-2-nitrosohydrazino)-N-methyl-1-hexanamine (MAHMA NONOate) and 1-(hydroxy-NNO-azoxy)-L-proline, disodium salt, was investigated using Pseudomonas aeruginosa PAO1 as a model organism. Dispersal was quantitatively assessed by confocal microscopy [bacterial cells and the components of the extracellular polymeric substances (EPS) (polysaccharides and extracellular DNA)] and colony-forming unit counts. The three NO donor compounds had different optimal exposure times and concentrations, with MAHMA NONOate being the optimal NO donor compound. Biofilm dispersal correlated with a reduction in both bacterial cells and EPS. MAHMA NONOate also reduced single species biofilms formed by bacteria isolated from industrial membrane bioreactor and reverse osmosis membranes, as well as in isolates combined to generate mixed species biofilms. The data present strong evidence for the application of these NO donor compounds for prevention of biofouling in an industrial setting.
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Affiliation(s)
- Robert J Barnes
- Advanced Environmental Biotechnology Centre, Nanyang Technological University, Singapore, Singapore
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Chen X, Suwarno SR, Chong TH, McDougald D, Kjelleberg S, Cohen Y, Fane AG, Rice SA. Dynamics of biofilm formation under different nutrient levels and the effect on biofouling of a reverse osmosis membrane system. Biofouling 2013; 29:319-330. [PMID: 23528128 DOI: 10.1080/08927014.2013.772141] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Pseudomonas aeruginosa PAO1 wild type and a mucoid derivative (FRD1) which over produces alginate were used to foul reverse osmosis (RO) membranes. When operated at a constant flux, biofilm formation on the RO membrane resulted in a slow rise in transmembrane pressure (TMP) of 22% for the initial four days of operation, followed by a sharp increase of 159% over the following two days. The initial slow increase in TMP was probably due to the formation of a biofilm on the membrane surface, which then accelerated the rate of biofouling through the effect of concentration polarization. At later stages of operation, most of the bacterial biomass consisted of dead cells. The amount of extracellular polymeric substances appeared to correlate positively with the number of dead cells. The results indicate that prolonging the initial stage of slow TMP increase and avoiding the latter stage of accelerated TMP increase would provide a sustainable operation of the RO system. These results suggest that nutrient limitation could reduce biofilm accumulation and delay the increase in TMP.
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Affiliation(s)
- Xi Chen
- Advanced Environmental Biotechnology Centre-Nanyang Environment & Water Research Institute (AEBC-NEWRI), Nanyang Technological University (NTU), Singapore
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Raingeard D, Ng C, Seow WY, Jinyu BC, Guest J, Steinberg P, McDougald D. Evolution from Bacteria to Mammalia of selected marker genes involved in energy metabolism and stress responses: Bioinformatic approach and applications in coral reef ecology. Comp Biochem Physiol A Mol Integr Physiol 2012. [DOI: 10.1016/j.cbpa.2012.05.087] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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Ng C, Raingeard D, Chan A, Steinberg P, McDougald D. qPCR detection of hepto- and neuro- cyanotoxins in a Singaporean reservoir system. Comp Biochem Physiol A Mol Integr Physiol 2012. [DOI: 10.1016/j.cbpa.2012.05.081] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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Huynh TT, McDougald D, Klebensberger J, Al Qarni B, Barraud N, Rice SA, Kjelleberg S, Schleheck D. Glucose starvation-induced dispersal of Pseudomonas aeruginosa biofilms is cAMP and energy dependent. PLoS One 2012; 7:e42874. [PMID: 22905180 PMCID: PMC3419228 DOI: 10.1371/journal.pone.0042874] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2012] [Accepted: 07/12/2012] [Indexed: 01/29/2023] Open
Abstract
Carbon starvation has been shown to induce a massive dispersal event in biofilms of the opportunistic pathogen Pseudomonas aeruginosa; however, the molecular pathways controlling this dispersal response remain unknown. We quantified changes in the proteome of P. aeruginosa PAO1 biofilm and planktonic cells during glucose starvation by differential peptide-fingerprint mass-spectrometry (iTRAQ). In addition, we monitored dispersal photometrically, as a decrease in turbidity/opacity of biofilms pre-grown and starved in continuous flow-cells, in order to evaluate treatments (e.g. inhibitors CCCP, arsenate, chloramphenicol, L-serine hydroxamate) and key mutants altered in biofilm development and dispersal (e.g. nirS, vfr, bdlA, rpoS, lasRrhlR, Pf4-bacteriophage and cyaA). In wild-type biofilms, dispersal started within five minutes of glucose starvation, was maximal after 2 h, and up to 60% of the original biomass had dispersed after 24 h of starvation. The changes in protein synthesis were generally not more than two fold and indicated that more than 100 proteins belonging to various classes, including carbon and energy metabolism, stress adaptation, and motility, were differentially expressed. For the different treatments, only the proton-ionophore CCCP or arsenate, an inhibitor of ATP synthesis, prevented dispersal of the biofilms. For the different mutants tested, only cyaA, the synthase of the intracellular second messenger cAMP, failed to disperse; complementation of the cyaA mutation restored the wild-type phenotype. Hence, the pathway for carbon starvation-induced biofilm dispersal in P. aeruginosa PAO1 involves ATP production via direct ATP synthesis and proton-motive force dependent step(s) and is mediated through cAMP, which is likely to control the activity of proteins involved in remodeling biofilm cells in preparation for planktonic survival.
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Affiliation(s)
- Tran T. Huynh
- Centre for Marine Bio-Innovation, School of Biotechnology and Biomolecular Science, University of New South Wales, Sydney, Australia
| | - Diane McDougald
- Centre for Marine Bio-Innovation, School of Biotechnology and Biomolecular Science, University of New South Wales, Sydney, Australia
- Advanced Environmental Biotechnology Centre, Nanyang Technological University, Singapore, Singapore
- * E-mail:
| | - Janosch Klebensberger
- Centre for Marine Bio-Innovation, School of Biotechnology and Biomolecular Science, University of New South Wales, Sydney, Australia
| | - Budoor Al Qarni
- Centre for Marine Bio-Innovation, School of Biotechnology and Biomolecular Science, University of New South Wales, Sydney, Australia
| | - Nicolas Barraud
- Centre for Marine Bio-Innovation, School of Biotechnology and Biomolecular Science, University of New South Wales, Sydney, Australia
| | - Scott A. Rice
- Centre for Marine Bio-Innovation, School of Biotechnology and Biomolecular Science, University of New South Wales, Sydney, Australia
- The Singapore Centre on Environmental Life Sciences Engineering, Nanyang Technological University, Singapore, Singapore
| | - Staffan Kjelleberg
- Centre for Marine Bio-Innovation, School of Biotechnology and Biomolecular Science, University of New South Wales, Sydney, Australia
- The Singapore Centre on Environmental Life Sciences Engineering, Nanyang Technological University, Singapore, Singapore
| | - David Schleheck
- Department of Biological Sciences and Research School Chemical Biology, University of Konstanz, Konstanz, Germany
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Lay WCL, Zhang Q, Zhang J, McDougald D, Tang C, Wang R, Liu Y, Fane AG. Effect of Pharmaceuticals on the Performance of a Novel Osmotic Membrane Bioreactor (OMBR). SEP SCI TECHNOL 2012. [DOI: 10.1080/01496395.2011.630249] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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Fagerlind MG, Webb JS, Barraud N, McDougald D, Jansson A, Nilsson P, Harlén M, Kjelleberg S, Rice SA. Dynamic modelling of cell death during biofilm development. J Theor Biol 2012; 295:23-36. [DOI: 10.1016/j.jtbi.2011.10.007] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2010] [Revised: 09/21/2011] [Accepted: 10/04/2011] [Indexed: 11/16/2022]
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Steinberg PD, Rice SA, Campbell AH, McDougald D, Harder T. Interfaces Between Bacterial and Eukaryotic "Neuroecology". Integr Comp Biol 2011; 51:794-806. [DOI: 10.1093/icb/icr115] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
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Abstract
Previous laboratory experiments revealed that Vibrio cholerae A1552 biofilms secrete an antiprotozoal factor that prevents Rhynchomonas nasuta from growing and thus prevents grazing losses. The antiprotozoal factor is regulated by the quorum-sensing response regulator, HapR. Here, we investigate whether the antiprotozoal activity is ecologically relevant. Experiments were conducted in the field as well as under field-like conditions in the laboratory to assess the grazing resistance of V. cholerae A1552 and N16961 (natural frameshift mutation in hapR) biofilms to R. nasuta and Cafeteria roenbergensis. In laboratory experiments exposing the predators to V. cholerae grown in seawater containing high and low glucose concentrations, we determined that V. cholerae biofilms showed increased resistance towards grazing by both predators as glucose levels decreased. The relative resistance of the V. cholerae strains to the grazers under semi-field conditions was similar to that observed in situ. Therefore, the antipredator defense is environmentally relevant and not lost when biofilms are grown in an open system in the marine environment. The hapR mutant still exhibited some resistance to both predators and this suggests that V. cholerae may coordinate antipredator defenses by a combination of density-dependent regulation and environmental sensing to protect itself from predators in its natural habitat.
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Affiliation(s)
- Martina Erken
- Centre for Marine Bio-Innovation and School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW, Australia
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Mueller RS, McDougald D, Cusumano D, Sodhi N, Kjelleberg S, Azam F, Bartlett DH. Vibrio cholerae strains possess multiple strategies for abiotic and biotic surface colonization. J Bacteriol 2007; 189:5348-60. [PMID: 17496082 PMCID: PMC1951843 DOI: 10.1128/jb.01867-06] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Despite its notoriety as a human pathogen, Vibrio cholerae is an aquatic microbe suited to live in freshwater, estuarine, and marine environments where biofilm formation may provide a selective advantage. Here we report characterization of biofilms formed on abiotic and biotic surfaces by two non-O1/O139 V. cholerae strains, TP and SIO, and by the O1 V. cholerae strain N16961 in addition to the isolation of 44 transposon mutants of SIO and TP impaired in biofilm formation. During the course of characterizing the mutants, 30 loci which have not previously been associated with V. cholerae biofilms were identified. These loci code for proteins which perform a wide variety of functions, including amino acid metabolism, ion transport, and gene regulation. Also, when the plankton colonization abilities of strains N16961, SIO, and TP were examined, each strain showed increased colonization of dead plankton compared with colonization of live plankton (the dinoflagellate Lingulodinium polyedrum and the copepod Tigriopus californicus). Surprisingly, most of the biofilm mutants were not impaired in plankton colonization. Only mutants impaired in motility or chemotaxis showed reduced colonization. These results indicate the presence of both conserved and variable genes which influence the surface colonization properties of different V. cholerae subspecies.
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Affiliation(s)
- Ryan S Mueller
- Marine Biology Research Division, Scripps Institution of Oceanography, University of Caifornia, San Diego, La Jolla, CA 92037, USA
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McDougald D, Rice SA, Kjelleberg S. Bacterial quorum sensing and interference by naturally occurring biomimics. Anal Bioanal Chem 2006; 387:445-53. [PMID: 17019574 DOI: 10.1007/s00216-006-0761-2] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2006] [Revised: 08/08/2006] [Accepted: 08/11/2006] [Indexed: 11/24/2022]
Abstract
Bacteria are able to coordinate gene expression as a community through the secretion and detection of signalling molecules so that the members of the community can simultaneously express specific behaviours. This mechanism of regulation of behaviour appears to be a key trait for adaptation to specific environments and has been shown to regulate a variety of important phenotypes, from virulence factor production to biofilm formation to symbiosis related behaviours such as bioluminescence. The ability to communicate and communally regulate gene expression is hypothesised to have evolved as a way for organisms to delay expression of phenotypes until numerical supremacy is reached. For example, in the case of infection, if an invading microorganism were to express virulence factors too early, the host may be able to mount a successful defence and repel the invaders. There is growing evidence that bacterial quorum sensing (QS) systems are involved in cross-kingdom signalling with eukaryotic organisms and that eukaryotes are capable of actively responding to bacteria in their environment by detecting and acting upon the presence of these signalling molecules. Likewise, eukaryotes produce compounds that can interfere with QS systems in bacteria by acting as agonists or antagonists. An exciting new field of study, biomimetics, takes inspiration from nature's models and attempts to design solutions to human problems, and biomimics of QS systems may be one such solution. This article presents the acylated homoserine lactone and autoinducer 2 QS systems in bacteria, the means of intercepting or interfering with bacterial QS systems evolved by eukaryotes, and the rational design of synthetic antagonists.
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Affiliation(s)
- Diane McDougald
- The Centre for Marine Biofouling and Bio-Innovation, The University of New South Wales, Sydney, NSW, 2052, Australia
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Abstract
Bacterial communication has risen to prominence in microbiology as a dynamic research topic, both because of its role in microbial ecology and evolution and for the opportunity it offers to control pathogenic microbial activity. Bacterial communication has evolved from the metabolic processes of prokaryotic cellular life, in which the biosynthesis and breakdown of chemical compounds in central metabolism generates secondary metabolites with ambiguous utility in natural selection.
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McDougald D, Lin WH, Rice SA, Kjelleberg S. The role of quorum sensing and the effect of environmental conditions on biofilm formation by strains of Vibrio vulnificus. Biofouling 2006; 22:133-44. [PMID: 17290858 DOI: 10.1080/08927010600691879] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
It has been suggested that Vibrio vulnificus attaches to plankton and algae and is found in large numbers in the environment. Factors affecting attachment, biofilm formation and morphology of V. vulnificus have not been thoroughly investigated. This study evaluated the role of quorum sensing (QS) and environmental conditions on biofilm development of V. vulnificus. It was found that biofilm development by V. vulnificus was affected by nutrient and glucose concentration, but not by NaCl concentration or temperature under the conditions used here. Moreover, biofilm development of a QS mutant strain proceeded rapidly and sloughing occurred earlier than for the isogenic parent strain. There was a significant loss of viability for the QS mutant biofilm early in development. Hence, it is hypothesised that factors regulated by the QS system play a role in proper biofilm development and maintenance of V. vulnificus. Furthermore, it is shown that biofilm development varied among isolates.
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Affiliation(s)
- D McDougald
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, Australia
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