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Jimoh AA, Booysen E, van Zyl L, Trindade M. Do biosurfactants as anti-biofilm agents have a future in industrial water systems? Front Bioeng Biotechnol 2023; 11:1244595. [PMID: 37781531 PMCID: PMC10540235 DOI: 10.3389/fbioe.2023.1244595] [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] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Accepted: 09/04/2023] [Indexed: 10/03/2023] Open
Abstract
Biofilms are bacterial communities embedded in exopolymeric substances that form on the surfaces of both man-made and natural structures. Biofilm formation in industrial water systems such as cooling towers results in biofouling and biocorrosion and poses a major health concern as well as an economic burden. Traditionally, biofilms in industrial water systems are treated with alternating doses of oxidizing and non-oxidizing biocides, but as resistance increases, higher biocide concentrations are needed. Using chemically synthesized surfactants in combination with biocides is also not a new idea; however, these surfactants are often not biodegradable and lead to accumulation in natural water reservoirs. Biosurfactants have become an essential bioeconomy product for diverse applications; however, reports of their use in combating biofilm-related problems in water management systems is limited to only a few studies. Biosurfactants are powerful anti-biofilm agents and can act as biocides as well as biodispersants. In laboratory settings, the efficacy of biosurfactants as anti-biofilm agents can range between 26% and 99.8%. For example, long-chain rhamnolipids isolated from Burkholderia thailandensis inhibit biofilm formation between 50% and 90%, while a lipopeptide biosurfactant from Bacillus amyloliquefaciens was able to inhibit biofilms up to 96% and 99%. Additionally, biosurfactants can disperse preformed biofilms up to 95.9%. The efficacy of antibiotics can also be increased by between 25% and 50% when combined with biosurfactants, as seen for the V9T14 biosurfactant co-formulated with ampicillin, cefazolin, and tobramycin. In this review, we discuss how biofilms are formed and if biosurfactants, as anti-biofilm agents, have a future in industrial water systems. We then summarize the reported mode of action for biosurfactant molecules and their functionality as biofilm dispersal agents. Finally, we highlight the application of biosurfactants in industrial water systems as anti-fouling and anti-corrosion agents.
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Affiliation(s)
| | | | | | - Marla Trindade
- Department of Biotechnology, Institute for Microbial Biotechnology and Metagenomics (IMBM), University of the Western Cape, Cape Town, South Africa
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Amanna R, Rakshit SK. Review of nomenclature and methods of analysis of polyethylene terephthalic acid hydrolyzing enzymes activity. Biodegradation 2023:10.1007/s10532-023-10048-z. [PMID: 37688750 DOI: 10.1007/s10532-023-10048-z] [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] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Accepted: 08/15/2023] [Indexed: 09/11/2023]
Abstract
Enzymatic degradation of polyethylene terephthalic acid (PET) has been gaining increasing importance. This has resulted in a significant increase in the search for newer enzymes and the development of more efficient enzyme-based systems. Due to the lack of a standard screening process, screening new enzymes has relied on other assays to determine the presence of esterase activity. This, in turn, has led to various nomenclatures and methods used to describe them and measure their activity. Since all PET-hydrolyzing enzymes are α/β hydrolases, they catalyze a serine nucleophilic attack and cleave an ester bond. They are lipases, esterases, cutinases and hydrolases. This has been used interchangeably, leading to difficulties while comparing results and evaluating progress. This review discusses the varied enzyme nomenclature being adapted, the different assays and analysis methods reported, and the strategies used to increase PET-hydrolyzing enzyme efficiency. A section on the various ways to quantify PET hydrolysis is also covered.
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Affiliation(s)
- Ruth Amanna
- Department of Biotechnology, Lakehead University, Thunder Bay, ON, Canada
- Biorefining Research Institute (BRI), Lakehead University, Thunder Bay, ON, Canada
| | - Sudip K Rakshit
- Department of Biotechnology, Lakehead University, Thunder Bay, ON, Canada.
- Biorefining Research Institute (BRI), Lakehead University, Thunder Bay, ON, Canada.
- Department of Chemical Engineering, Lakehead University, Thunder Bay, ON, Canada.
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Garg SS, Dubey R, Sharma S, Vyas A, Gupta J. Biological macromolecules-based nanoformulation in improving wound healing and bacterial biofilm-associated infection: A review. Int J Biol Macromol 2023; 247:125636. [PMID: 37392924 DOI: 10.1016/j.ijbiomac.2023.125636] [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] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2023] [Revised: 06/19/2023] [Accepted: 06/28/2023] [Indexed: 07/03/2023]
Abstract
A chronic wound is a serious complication associated with diabetes mellitus and is difficult to heal due to high glucose levels, oxidative stress, and biofilm-associated microbial infection. The structural complexity of microbial biofilm makes it impossible for antibiotics to penetrate the matrix, hence conventional antibiotic therapies became ineffective in clinical settings. This demonstrates an urgent need to find safer alternatives to reduce the prevalence of chronic wound infection associated with microbial biofilm. A novel approach to address these concerns is to inhibit biofilm formation using biological-macromolecule based nano-delivery system. Higher drug loading efficiency, sustained drug release, enhanced drug stability, and improved bioavailability are advantages of employing nano-drug delivery systems to prevent microbial colonization and biofilm formation in chronic wounds. This review covers the pathogenesis, microbial biofilm formation, and immune response to chronic wounds. Furthermore, we also focus on macromolecule-based nanoparticles as wound healing therapies to reduce the increased mortality associated with chronic wound infections.
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Affiliation(s)
- Sourbh Suren Garg
- Department of Biochemistry, School of Bioengineering and Biosciences, Lovely Professional University, Punjab, India
| | - Rupal Dubey
- Department of Medical Laboratory Sciences, School of Allied Medical Sciences, Lovely Professional University, Punjab, India
| | - Sandeep Sharma
- Department of Medical Laboratory Sciences, School of Allied Medical Sciences, Lovely Professional University, Punjab, India
| | - Ashish Vyas
- Department of Microbiology, School of Bioengineering and Biosciences, Lovely Professional University, Punjab, India
| | - Jeena Gupta
- Department of Biochemistry, School of Bioengineering and Biosciences, Lovely Professional University, Punjab, India.
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Viggor S, Jõesaar M, Peterson C, Teras R, Kivisaar M. Potential of Indigenous Strains Isolated from the Wastewater Treatment Plant of a Crude Oil Refinery. Microorganisms 2023; 11:microorganisms11030752. [PMID: 36985325 PMCID: PMC10051678 DOI: 10.3390/microorganisms11030752] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Revised: 03/09/2023] [Accepted: 03/13/2023] [Indexed: 03/17/2023] Open
Abstract
Contamination of the environment with crude oil or other fuels is an enormous disaster for all organisms. The microbial communities for bioremediation have been an effective tool for eliminating pollution. This study aimed to determine individual cultures’ and a strain mixture’s ability to utilize alkanes (single alkanes and crude oil). The proper study of pure cultures is necessary to design synergistically working consortia. The Acinetobacter venetianus ICP1 and Pseudomonas oleovorans ICTN13 strains isolated from a wastewater treatment plant of a crude oil refinery can grow in media containing various aromatic and aliphatic hydrocarbons. The genome of the strain ICP1 contains four genes encoding alkane hydroxylases, whose transcription depended on the length of the alkane in the media. We observed that the hydrophobic cells of the strain ICP1 adhered to hydrophobic substrates, and their biofilm formation increased the bioavailability and biodegradation of the hydrocarbons. Although strain ICTN13 also has one alkane hydroxylase-encoding gene, the growth of the strain in a minimal medium containing alkanes was weak. Importantly, the growth of the mixture of strains in the crude oil-containing medium was enhanced compared with that of the single strains, probably due to the specialization in the degradation of different hydrocarbon classes and co-production of biosurfactants.
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Affiliation(s)
- Signe Viggor
- Institute of Molecular and Cell Biology, University of Tartu, 23 Riia Street, 51010 Tartu, Estonia
- Correspondence:
| | - Merike Jõesaar
- Institute of Molecular and Cell Biology, University of Tartu, 23 Riia Street, 51010 Tartu, Estonia
| | - Celeste Peterson
- Institute of Molecular and Cell Biology, University of Tartu, 23 Riia Street, 51010 Tartu, Estonia
- Institute of Biomedicine and Translational Medicine, University of Tartu, 19 Ravila Street, 50411 Tartu, Estonia
| | - Riho Teras
- Institute of Molecular and Cell Biology, University of Tartu, 23 Riia Street, 51010 Tartu, Estonia
| | - Maia Kivisaar
- Institute of Molecular and Cell Biology, University of Tartu, 23 Riia Street, 51010 Tartu, Estonia
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Li H, Yang Y, Zhang D, Li Y, Zhang H, Luo J, Jones KC. Evaluating the simulated toxicities of metal mixtures and hydrocarbons using the alkane degrading bioreporter Acinetobacter baylyi ADPWH_recA. J Hazard Mater 2021; 419:126471. [PMID: 34216972 DOI: 10.1016/j.jhazmat.2021.126471] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [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: 02/09/2021] [Revised: 06/19/2021] [Accepted: 06/21/2021] [Indexed: 06/13/2023]
Abstract
Oil spillages lead to the formation of hydrocarbon and metal mixtures possessing effects on alkane-degrading bacteria that are responsible for the bioremediation of oil-contaminated soils and waters. Studies of bacterial responses to the mixture of petroleum and metal can inform appropriate strategies for bioremediation. We employed a luminescent bioreporter Acinetobacter baylyi ADPWH_recA with alkane degradation capability to evaluate the combined effects from heavy metals (Cd, Pb and Cu) and alkanes (dodecane, tetradecane, hexadecane and octadecane). Bioluminescent ratios of ADPWH_recA in single Cd or Pb treatments ranged from 0.25 to 1.98, indicating both genotoxicity and cytotoxicity of these two metals, while ratios < 1.0 postexposure to Cu showed its cytotoxic impacts on ADPWH_recA bioreporter. Metal mixtures exhibited enhanced antagonistic effects (Ti>4.0) determined by the Toxic Unit model. With 100 mg/L alkane, the morbidity of ADPWH-recA reduced to < 20%, showing the inhibition of alkanes on Cd toxicity. Exposed to the metal mixture containing 10 mg/L Cu, the weak binding affinity of Cu with alkanes contributed to a high morbidity of > 85% in ADPWH_recA cells. This study provides a new way to understand the toxicity of mixture contaminants, which can help to optimize treatment efficiencies of bacterial remediation for oil contamination.
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Affiliation(s)
- Hanbing Li
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023, China; Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, UK; Key Laboratory of Beijing on Regional Air Pollution Control, Faculty of Environment and Life, Beijing University of Technology, Beijing 100124, China
| | - Yi Yang
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023, China
| | - Dayi Zhang
- School of Environment, Tsinghua University, Beijing 100086, China
| | - Yanying Li
- Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, UK
| | - Hao Zhang
- Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, UK
| | - Jun Luo
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023, China.
| | - Kevin C Jones
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023, China; Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, UK.
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Abstract
The high demand for petroleum oil has led to hydrocarbon contamination in soil, including agricultural lands, and many other ecosystems across the globe. Physical and chemical treatments are effective strategies for the removal of high contamination levels and are useful for small areas, although with concerns of cost-effectiveness. Alternatively, several bacteria belonging to the Phylum: Proteobacteria, Bacteroidetes, Actinobacteria, Nocardioides, or Firmicutes are used for biodegradation of different hydrocarbons - aliphatic, polyaromatic hydrocarbons (PAH), and asphaltenes in the oil-contaminated soil. The rhizoremediation strategy with plant-microbe interactions has prospects to achieve the desired result in the field conditions. However, adequate biostimulation, and bioaugmentation with the suitable plant-microbe combination, and efficiency under a toxic environment needs to be evaluated. Modifying the microbiomes to achieve better biodegradation of contaminants is an upcoming strategy popularly known as microbiome engineering. In this review, rhizoremediation for the successful removal of the hydrocarbons have been critically discussed, with challenges for making it a feasible technology.HIGHLIGHTSPetroleum hydrocarbon contamination has increased around the globe.Rhizoremediation has the potential for the mitigation of pollutants from the contaminated sites.An accurate and detailed analysis of the physio-chemical and climatic conditions of the contaminated sites must be focused on.The suitable plant and bacteria, with other major considerations, may be employed for in-situ remediation.The appropriate data should be obtained using the omics approach to help toward the success of the rhizoremediation strategy.
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Affiliation(s)
| | - Piyush Pandey
- Department of Microbiology, Assam University, Silchar, India
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Li H, Zhang D, Luo J, Jones KC, Martin FL. Applying Raman Microspectroscopy to Evaluate the Effects of Nutrient Cations on Alkane Bioavailability to Acinetobacter baylyi ADP1. Environ Sci Technol 2020; 54:15800-15810. [PMID: 33274919 DOI: 10.1021/acs.est.0c04944] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Contamination with petroleum hydrocarbons causes extensive damage to ecological systems. On oil-contaminated sites, alkanes are major components; many indigenous bacteria can access and/or degrade alkanes. However, their ability to do so is affected by external properties of the soil, including nutrient cations. This study used Raman microspectroscopy to study how nutrient cations affect alkanes' bioavailability to Acinetobacter baylyi ADP1 (a known degrader). Treated with Na, K, Mg, and Ca at 10 mM, A. baylyi was exposed to seven n-alkanes (decane, dodecane, tetradecane, hexadecane, nonadecane, eicosane, and tetracosane) and one alkane mixture (mineral oil). Raman spectral analysis indicated that bioavailability of alkanes varied with carbon chain lengths, and additional cations altered the bacterial response to n-alkanes. Sodium significantly increased the bacterial affinity toward decane and dodecane, and K and Mg enhanced the bioavailability of tetradecane and hexadecane. In contrast, the bacterial response was inhibited by Ca for all alkanes. Similar results were observed in mineral oil exposure. Our study employed Raman spectral assay to offer a deep insight into how nutrient cations affect the bioavailability of alkanes, suggesting that nutrient cations can play a key role in influencing the harmful effects of hydrocarbons and could be optimized to enhance the bioremediation strategy.
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Affiliation(s)
- Hanbing Li
- Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, U.K
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023, China
| | - Dayi Zhang
- Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, U.K
- School of Environment, Tsinghua University, Beijing 100086, China
| | - Jun Luo
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023, China
| | - Kevin C Jones
- Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, U.K
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023, China
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Prem Anand K, Suthindhiran K. Biofilm formation and pathogenicity of marine-derived Acinetobacter sp. VITRSA1 in Paratelphusa hydrodromous and its toluene remediation. Biocatalysis and Agricultural Biotechnology 2020. [DOI: 10.1016/j.bcab.2020.101723] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Conrad JC. Biophysical methods to quantify bacterial behaviors at oil-water interfaces. J Ind Microbiol Biotechnol 2020; 47:725-38. [PMID: 32743734 DOI: 10.1007/s10295-020-02293-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2020] [Accepted: 07/16/2020] [Indexed: 02/03/2023]
Abstract
Motivated by the need for improved understanding of physical processes involved in bacterial biodegradation of catastrophic oil spills, we review biophysical methods to probe bacterial motility and adhesion at oil-water interfaces. This review summarizes methods that probe bulk, average behaviors as well as local, microscopic behaviors, and highlights opportunities for future work to bridge the gap between biodegradation and biophysics.
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Asadpoor M, Peeters C, Henricks PAJ, Varasteh S, Pieters RJ, Folkerts G, Braber S. Anti-Pathogenic Functions of Non-Digestible Oligosaccharides In Vitro. Nutrients 2020; 12:E1789. [PMID: 32560186 DOI: 10.3390/nu12061789] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Revised: 06/10/2020] [Accepted: 06/12/2020] [Indexed: 12/11/2022] Open
Abstract
Non-digestible oligosaccharides (NDOs), complex carbohydrates that resist hydrolysis by salivary and intestinal digestive enzymes, fulfill a diversity of important biological roles. A lot of NDOs are known for their prebiotic properties by stimulating beneficial bacteria in the intestinal microbiota. Human milk oligosaccharides (HMOs) represent the first prebiotics that humans encounter in life. Inspired by these HMO structures, chemically-produced NDO structures (e.g., galacto-oligosaccharides and chito-oligosaccharides) have been recognized as valuable food additives and exert promising health effects. Besides their apparent ability to stimulate beneficial microbial species, oligosaccharides have shown to be important inhibitors of the development of pathogenic infections. Depending on the type and structural characteristics, oligosaccharides can exert a number of anti-pathogenic effects. The most described effect is their ability to act as a decoy receptor, thereby inhibiting adhesion of pathogens. Other ways of pathogenic inhibition, such as interference with pathogenic cell membrane and biofilm integrity and DNA transcription, are less investigated, but could be equally impactful. In this review, a comprehensive overview of In vitro anti-pathogenic properties of different NDOs and associated pathways are discussed. A framework is created categorizing all anti-pathogenic effects and providing insight into structural necessities for an oligosaccharide to exert one of these effects.
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Sivadon P, Barnier C, Urios L, Grimaud R. Biofilm formation as a microbial strategy to assimilate particulate substrates. Environ Microbiol Rep 2019; 11:749-764. [PMID: 31342619 DOI: 10.1111/1758-2229.12785] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Revised: 07/15/2019] [Accepted: 07/21/2019] [Indexed: 06/10/2023]
Abstract
In most ecosystems, a large part of the organic carbon is not solubilized in the water phase. Rather, it occurs as particles made of aggregated hydrophobic and/or polymeric natural or man-made organic compounds. These particulate substrates are degraded by extracellular digestion/solubilization implemented by heterotrophic bacteria that form biofilms on them. Organic particle-degrading biofilms are widespread and have been observed in aquatic and terrestrial natural ecosystems, in polluted and man-driven environments and in the digestive tracts of animals. They have central ecological functions as they are major players in carbon recycling and pollution removal. The aim of this review is to highlight bacterial adhesion and biofilm formation as central mechanisms to exploit the nutritive potential of organic particles. It focuses on the mechanisms that allow access and assimilation of non-dissolved organic carbon, and considers the advantage provided by biofilms for gaining a net benefit from feeding on particulate substrates. Cooperative and competitive interactions taking place in biofilms feeding on particulate substrates are also discussed.
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Affiliation(s)
- Pierre Sivadon
- CNRS/Université de Pau et des Pays de l'Adour/E2S UPPA, Institut des Sciences Analytiques et de Physico-Chimie pour l'Environnement et les Matériaux UMR5254, Pau, 64000, France
| | - Claudie Barnier
- CNRS/Université de Pau et des Pays de l'Adour/E2S UPPA, Institut des Sciences Analytiques et de Physico-Chimie pour l'Environnement et les Matériaux UMR5254, Pau, 64000, France
| | - Laurent Urios
- CNRS/Université de Pau et des Pays de l'Adour/E2S UPPA, Institut des Sciences Analytiques et de Physico-Chimie pour l'Environnement et les Matériaux UMR5254, Pau, 64000, France
| | - Régis Grimaud
- CNRS/Université de Pau et des Pays de l'Adour/E2S UPPA, Institut des Sciences Analytiques et de Physico-Chimie pour l'Environnement et les Matériaux UMR5254, Pau, 64000, France
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Aguayo S, Schuh CMAP, Vicente B, Aguayo LG. Association between Alzheimer's Disease and Oral and Gut Microbiota: Are Pore Forming Proteins the Missing Link? J Alzheimers Dis 2019; 65:29-46. [PMID: 30040725 DOI: 10.3233/jad-180319] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Alzheimer's disease (AD) is a neurodegenerative condition affecting millions of people worldwide. It is associated with cerebral amyloid-β (Aβ) plaque deposition in the brain, synaptic disconnection, and subsequent progressive neuronal death. Although considerable progress has been made to elucidate the pathogenesis of AD, the specific causes of the disease remain highly unknown. Recent research has suggested a potential association between certain infectious diseases and dementia, either directly due to bacterial brain invasion and toxin production, or indirectly by modulating the immune response. Therefore, in the present review we focus on the emerging issues of bacterial infection and AD, including the existence of antimicrobial peptides having pore-forming properties that act in a similar way to pores formed by Aβ in a variety of cell membranes. Special focus is placed on oral bacteria and biofilms, and on the potential mechanisms associating bacterial infection and toxin production in AD. The role of bacterial outer membrane vesicles on the transport and delivery of toxins as well as porins to the brain is also discussed. Aβ has shown to possess antimicrobial activity against several bacteria, and therefore could be upregulated as a response to bacteria and bacterial toxins in the brain. Although further research is needed, we believe that the control of biofilm-mediated diseases could be an important potential prevention mechanism for AD development.
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Boluki E, Moradi M, Azar PS, Fekrazad R, Pourhajibagher M, Bahador A. The effect of antimicrobial photodynamic therapy against virulence genes expression in colistin-resistance Acinetobacter baumannii. Laser Ther 2019; 28:27-33. [PMID: 31190695 DOI: 10.5978/islsm.28_19-or-03] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [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: 07/14/2018] [Accepted: 10/31/2018] [Indexed: 11/06/2022]
Abstract
Background and Aims The emergence of drug-resistant infections is a global problem. Acinetobacter baumannii has attracted much attention over the last few years because of resistance to a wide range of antibiotics. Applying new non-antibiotic methods can save lives of many people around the world. Antimicrobial photodynamic therapy (aPDT) technique can be used as a new method for controlling the infections. In this study we investigated the effect of aPDT on the expression of pathogenic genes in colistin-resistance A. baumannii isolated from a burn patient. Materials and methods The suspension of colistin-resistance A. baumannii was incubated with 0.01 mg/ml of toluidine blue O (TBO) in the dark; then the light emitting diode device with a wavelength of 630 ± 10 nm and output intensity of 2000-4000 mW /cm2 was irradiated to the suspension at room temperature. Subsequently, after the aPDT, genes expression of ompA and pilZ was investigated by using real-time polymerase chain reaction technique. Result Among the genes studied, the transcript of the ompA gene after aPDT was increased significantly in comparison with control groups (P < 0.05). Whereas, there was no remarkable different in pilZ gene expression (P > 0.05). Conclusions It can be concluded from the results that the ompA as an outer membrane of A. baumannii is degraded after exposing aPDT and it will probably be done the penetration of antibiotics into cells of this bacterium easily.
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Affiliation(s)
- Ebrahim Boluki
- Department of Microbiology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
| | - Maryam Moradi
- Department of Cell & Molecular Biology, Faculty of Biological Sciences, Kharazmi University, Tehran, Iran
| | | | - Reza Fekrazad
- Department of Periodontology, Dental Faculty - Laser research center in medical Sciences, AJA University of Medical Sciences, Tehran, Iran
| | - Maryam Pourhajibagher
- Dental Research Center, Dentistry Research Institute, Tehran University of Medical Sciences, Tehran, Iran
| | - Abbas Bahador
- Department of Microbiology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
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McLay RB, Nguyen HN, Jaimes-Lizcano YA, Dewangan NK, Alexandrova S, Rodrigues DF, Cirino PC, Conrad JC. Level of Fimbriation Alters the Adhesion of Escherichia coli Bacteria to Interfaces. Langmuir 2018; 34:1133-1142. [PMID: 28976770 DOI: 10.1021/acs.langmuir.7b02447] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Adhesion of bacteria to interfaces is the first step in pathogenic infection, in biofilm formation, and in bioremediation of oil spills and other pollutants. Bacteria use a variety of surface structures to promote interfacial adhesion, with the level of expression of these structures varying in response to local conditions and environmental signals. Here, we investigated how overexpression of type 1 fimbriae, one such appendage, modifies the ability of Escherichia coli to adhere to solid substrates, via biofilm formation and yeast agglomeration, and to oil/water interfaces, via a microbial adhesion to hydrocarbon assay. A plasmid that enables inducible expression of E. coli MG1655 type 1 fimbriae was transformed into fimbriae-deficient mutant strain MG1655ΔfimA. The level of fimH gene expression in the engineered strain, measured using quantitative real-time PCR, could be tuned by changing the concentration of inducer isopropyl β-d-1-thiogalactopyranoside (IPTG), and was higher than that in strain MG1655. Increasing the degree of fimbriation only slightly modified the surface energy and zeta potential of the bacteria, but enhanced their ability to agglomerate yeast cells and to adhere to solid substrates (as measured by biofilm formation) and to oil/water interfaces. We anticipate that the tunable extent of fimbriation accessible with this engineered strain can be used to investigate how adhesin expression modifies the ability of bacteria to adhere to interfaces and to actively self-assemble there.
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Affiliation(s)
- Ryan B McLay
- Department of Chemical and Biomolecular Engineering, University of Houston , Houston, Texas 77204-4004, United States
| | - Hang N Nguyen
- Department of Civil and Environmental Engineering, University of Houston , Houston, Texas 77204-4003, United States
| | - Yuly Andrea Jaimes-Lizcano
- Department of Chemical and Biomolecular Engineering, University of Houston , Houston, Texas 77204-4004, United States
| | - Narendra K Dewangan
- Department of Chemical and Biomolecular Engineering, University of Houston , Houston, Texas 77204-4004, United States
| | - Simone Alexandrova
- Department of Chemical and Biomolecular Engineering, University of Houston , Houston, Texas 77204-4004, United States
| | - Debora F Rodrigues
- Department of Civil and Environmental Engineering, University of Houston , Houston, Texas 77204-4003, United States
| | - Patrick C Cirino
- Department of Chemical and Biomolecular Engineering, University of Houston , Houston, Texas 77204-4004, United States
- Department of Biology and Biochemistry, University of Houston , Houston, Texas 77204-5008, United States
| | - Jacinta C Conrad
- Department of Chemical and Biomolecular Engineering, University of Houston , Houston, Texas 77204-4004, United States
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Oberding LK, Gieg LM. Methanogenic Paraffin Biodegradation: Alkylsuccinate Synthase Gene Quantification and Dicarboxylic Acid Production. Appl Environ Microbiol 2018; 84:e01773-17. [PMID: 29030441 PMCID: PMC5734044 DOI: 10.1128/aem.01773-17] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [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: 08/11/2017] [Accepted: 10/09/2017] [Indexed: 11/20/2022] Open
Abstract
Paraffinic n-alkanes (>C17) that are solid at ambient temperature comprise a large fraction of many crude oils. The comparatively low water solubility and reactivity of these long-chain alkanes can lead to their persistence in the environment following fuel spills and pose serious problems for crude oil recovery operations by clogging oil production wells. However, the degradation of waxy paraffins under the anoxic conditions characterizing contaminated groundwater environments and deep subsurface energy reservoirs is poorly understood. Here, we assessed the ability of a methanogenic culture enriched from freshwater fuel-contaminated aquifer sediments to biodegrade the model paraffin n-octacosane (C28H58). Compared with that in controls, the consumption of n-octacosane was coupled to methane production, demonstrating its biodegradation under these conditions. Smithella was postulated to be an important C28H58 degrader in the culture on the basis of its high relative abundance as determined by 16S rRNA gene sequencing. An identified assA gene (known to encode the α subunit of alkylsuccinate synthase) aligned most closely with those from other Smithella organisms. Quantitative PCR (qPCR) and reverse transcription qPCR assays for assA demonstrated significant increases in the abundance and expression of this gene in C28H58-degrading cultures compared with that in controls, suggesting n-octacosane activation by fumarate addition. A metabolite analysis revealed the presence of several long-chain α,ω-dicarboxylic acids only in the C28H58-degrading cultures, a novel observation providing clues as to how methanogenic consortia access waxy hydrocarbons. The results of this study broaden our understanding of how waxy paraffins can be biodegraded in anoxic environments with an application toward bioremediation and improved oil recovery.IMPORTANCE Understanding the methanogenic biodegradation of different classes of hydrocarbons has important applications for effective fuel-contaminated site remediation and for improved recovery from oil reservoirs. Previous studies have clearly demonstrated that short-chain alkanes (C17) that comprise many fuel mixtures. Using an enrichment culture derived from a freshwater fuel-contaminated site, we demonstrate that the model waxy alkane n-octacosane can be biodegraded under methanogenic conditions by a presumed Smithella phylotype. Compared with that of controls, we show an increased abundance and expression of the assA gene, which is known to be important for anaerobic n-alkane metabolism. Metabolite analyses revealed the presence of a range of α,ω-dicarboxylic acids found only in n-octacosane-degrading cultures, a novel finding that lends insight as to how anaerobic communities may access waxes as growth substrates in anoxic environments.
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Affiliation(s)
- Lisa K Oberding
- Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada
| | - Lisa M Gieg
- Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada
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18
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Park C, Shin B, Jung J, Lee Y, Park W. Metabolic and stress responses of Acinetobacter oleivorans DR1 during long-chain alkane degradation. Microb Biotechnol 2017; 10:1809-1823. [PMID: 28857443 PMCID: PMC5658608 DOI: 10.1111/1751-7915.12852] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [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: 10/27/2016] [Revised: 08/09/2017] [Accepted: 08/10/2017] [Indexed: 11/28/2022] Open
Abstract
Acinetobacter oleivorans DR1 can utilize C12–C30 alkanes as a sole carbon source but not short‐chain alkanes (C6, C10). Two copies of each alkB‐, almA‐ and ladA‐type alkane hydroxylase (AH) are present in the genome of DR1 cells. Expression and mutational analyses of AHs showed that alkB1 and alkB2 are the major AH‐encoding genes under C12–C30, and the roles of other almA‐ and ladA genes are negligible. Our data suggested that AlkB1 is responsible for long‐chain alkane utilization (C24–C26), and AlkB2 is important for medium‐chain alkane (C12–C16) metabolism. Phylogenetic analyses revealed large incongruities between phylogenies of 16S rRNA and each AH gene, which implies that A. oleivorans DR1 has acquired multiple alkane hydroxylases through horizontal gene transfer. Transcriptomic and qRT‐PCR analyses suggested that genes participating in the synthesis of siderophore, trehalose and poly 3‐hydroxybutyrate (PHB) were expressed at much higher levels when cells used C30 than when used succinate as a carbon source. The following biochemical assays supported our gene expression analyses: (i) quantification of siderophore, (ii) measurement of trehalose and (iii) observation of PHB storage. Interestingly, highly induced both ackA gene encoding an acetate kinase A and pta gene encoding a phosphotransacetylase suggested unusual ATP synthesis during C30 alkane degradation, which was demonstrated by ATP measurement using the ΔackA mutant. Impaired growth of the ΔaceA mutant indicated that the glyoxylate shunt pathway is important when C30 alkane is utilized. Our data provide insight into long‐chain alkane degradation in soil microorganisms.
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Affiliation(s)
- Chulwoo Park
- Laboratory of Molecular Environmental Microbiology, Department of Environmental Science and Ecological Engineering, Korea University, Seoul, 02841, Korea
| | - Bora Shin
- Laboratory of Molecular Environmental Microbiology, Department of Environmental Science and Ecological Engineering, Korea University, Seoul, 02841, Korea
| | - Jaejoon Jung
- National Marine Biodiversity Institute of Korea, Chungcheongnam-Do, 33662, Korea
| | - Yunho Lee
- Department of Life Science, Chung-Ang University, Seoul, 06974, Korea
| | - Woojun Park
- Laboratory of Molecular Environmental Microbiology, Department of Environmental Science and Ecological Engineering, Korea University, Seoul, 02841, Korea
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19
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Kothari A, Charrier M, Wu YW, Malfatti S, Zhou CE, Singer SW, Dugan L, Mukhopadhyay A. Transcriptomic analysis of the highly efficient oil-degrading bacterium Acinetobacter venetianus RAG-1 reveals genes important in dodecane uptake and utilization. FEMS Microbiol Lett 2016; 363:fnw224. [PMID: 27664055 PMCID: PMC5074533 DOI: 10.1093/femsle/fnw224] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [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] [Accepted: 09/22/2016] [Indexed: 02/04/2023] Open
Abstract
The hydrocarbonoclastic bacterium Acinetobacter venetianus RAG-1 has attracted substantial attention due to its powerful oil-degrading capabilities and its potential to play an important ecological role in the cleanup of alkanes. In this study, we compare the transcriptome of the strain RAG-1 grown in dodecane, the corresponding alkanol (dodecanol), and sodium acetate for the characterization of genes involved in dodecane uptake and utilization. Comparison of the transcriptional responses of RAG-1 grown on dodecane led to the identification of 1074 genes that were differentially expressed relative to sodium acetate. Of these, 622 genes were upregulated when grown in dodecane. The highly upregulated genes were involved in alkane catabolism, along with stress response. Our data suggest AlkMb to be primarily involved in dodecane oxidation. Transcriptional response of RAG-1 grown on dodecane relative to dodecanol also led to the identification of permease, outer membrane protein and thin fimbriae coding genes potentially involved in dodecane uptake. This study provides the first model for key genes involved in alkane uptake and metabolism in A. venetianus RAG-1. Analysis of the transcriptome of the oil-degrading bacterium Acinetobacter venetianus RAG-1 helps in identification of genes that are involved in uptake and metabolism of alkanes, thus helping in bioremediation.
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Affiliation(s)
- Ankita Kothari
- Biological Systems and Engineering, Lawrence Berkeley National Laboratory, Berkeley, CA 94720-8099, USA
| | - Marimikel Charrier
- Biological Systems and Engineering, Lawrence Berkeley National Laboratory, Berkeley, CA 94720-8099, USA
| | - Yu-Wei Wu
- Biological Systems and Engineering, Lawrence Berkeley National Laboratory, Berkeley, CA 94720-8099, USA.,Graduate Institute of Biomedical Informatics, Taipei Medical University, Taipei 110, Taiwan Biosciences
| | - Stephanie Malfatti
- Biotechnology Division, Lawrence Livermore National Laboratory, Livermore, CA 94550-5507, USA
| | - Carol E Zhou
- Computing Applications and Research Department, Lawrence Livermore National Laboratory, Livermore, CA 94550-9234, USA
| | - Steven W Singer
- Biological Systems and Engineering, Lawrence Berkeley National Laboratory, Berkeley, CA 94720-8099, USA
| | - Larry Dugan
- Graduate Institute of Biomedical Informatics, Taipei Medical University, Taipei 110, Taiwan Biosciences.,Biotechnology Division, Lawrence Livermore National Laboratory, Livermore, CA 94550-5507, USA
| | - Aindrila Mukhopadhyay
- Biological Systems and Engineering, Lawrence Berkeley National Laboratory, Berkeley, CA 94720-8099, USA
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20
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Miller R. Surfactant-Enhanced Bioavailability of Slightly Soluble Organic Compounds. In: Skipper H, Turco R, editors. Bioremediation. Madison: Soil Science Society of America, American Society of Agronomy, and Crop Science Society of America; 1995. pp. 33-54. [DOI: 10.2136/sssaspecpub43.c3] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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21
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Mnif I, Ghribi D. High molecular weight bioemulsifiers, main properties and potential environmental and biomedical applications. World J Microbiol Biotechnol 2015; 31:691-706. [PMID: 25739564 DOI: 10.1007/s11274-015-1830-5] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2014] [Accepted: 02/22/2015] [Indexed: 12/31/2022]
Abstract
High molecular weight bioemulsifiers are amphipathic polysaccharides, proteins, lipopolysaccharides, lipoproteins, or complex mixtures of these biopolymers, produced by a wide variety of microorganisms. They are characterized by highly structural diversity and have the ability to decrease the surface and interfacial tension at the surface and interface respectively and/or emulsify hydrophobic compounds. Emulsan, fatty acids, phospholipids, neutral lipids, exopolysaccharides, vesicles and fimbriae are among the most popular high molecular weight bioemulsifiers. They have great physic-chemical properties like tolerance to extreme conditions of pH, temperature and salinity, low toxicity and biodegradability. Owing their emulsion forming and breaking capacities, solubilization, mobilization and dispersion activities and their viscosity reduction activity; they possess great environmental application as enhancer of hydrocarbon biodegradation and for microbial enhanced oil recovery. Besides, they are applied in biomedical fields for their antimicrobial and anti-adhesive activities and involvement in immune responses.
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22
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23
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Fuentes S, Méndez V, Aguila P, Seeger M. Bioremediation of petroleum hydrocarbons: catabolic genes, microbial communities, and applications. Appl Microbiol Biotechnol 2014; 98:4781-94. [PMID: 24691868 DOI: 10.1007/s00253-014-5684-9] [Citation(s) in RCA: 153] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2014] [Revised: 03/10/2014] [Accepted: 03/11/2014] [Indexed: 01/22/2023]
Abstract
Bioremediation is an environmental sustainable and cost-effective technology for the cleanup of hydrocarbon-polluted soils and coasts. In spite of that longer times are usually required compared with physicochemical strategies, complete degradation of the pollutant can be achieved, and no further confinement of polluted matrix is needed. Microbial aerobic degradation is achieved by the incorporation of molecular oxygen into the inert hydrocarbon molecule and funneling intermediates into central catabolic pathways. Several families of alkane monooxygenases and ring hydroxylating dioxygenases are distributed mainly among Proteobacteria, Actinobacteria, Firmicutes and Fungi strains. Catabolic routes, regulatory networks, and tolerance/resistance mechanisms have been characterized in model hydrocarbon-degrading bacteria to understand and optimize their metabolic capabilities, providing the basis to enhance microbial fitness in order to improve hydrocarbon removal. However, microbial communities taken as a whole play a key role in hydrocarbon pollution events. Microbial community dynamics during biodegradation is crucial for understanding how they respond and adapt to pollution and remediation. Several strategies have been applied worldwide for the recovery of sites contaminated with persistent organic pollutants, such as polycyclic aromatic hydrocarbons and petroleum derivatives. Common strategies include controlling environmental variables (e.g., oxygen availability, hydrocarbon solubility, nutrient balance) and managing hydrocarbon-degrading microorganisms, in order to overcome the rate-limiting factors that slow down hydrocarbon biodegradation.
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Affiliation(s)
- Sebastián Fuentes
- Laboratorio de Microbiología Molecular y Biotecnología Ambiental, Departamento de Química & Centro de Biotecnología & Center of Nanotechnology and Systems Biology, Universidad Técnica Federico Santa María, Valparaíso, Chile
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24
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Swaathy S, Kavitha V, Sahaya Pravin A, Sekaran G, Mandal AB, Gnanamani A. Phylogenetic Framework and Biosurfactant Gene Expression Analysis of Marine Bacillus spp. of Eastern Coastal Plain of Tamil Nadu. Int J Bacteriol 2014; 2014:860491. [PMID: 26904741 DOI: 10.1155/2014/860491] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Accepted: 12/17/2013] [Indexed: 12/01/2022]
Abstract
The present study emphasizes the diversity assessment of marine Bacillus species with special reference to biosurfactant production, respective gene expression, and discrimination among Bacillus licheniformis and Bacillus subtilis. Among the 200 individual species of eastern coastal plain of Tamil Nadu screened, five biosurfactant producing potential bacterial species with entirely different morphology were selected. Biochemical and 16S rRNA gene sequence analysis suggested that all the said five species belong to Bacillus genera but differ in species levels. Biosurfactant of all the five species fluctuates in greater levels with respect to activity as well as to constituents but showed partial similarity to the commercially available surfactin. The expression of srf gene was realized in all of the five species. However, the sfp gene expression was observed only in three species. In conclusion, both B. licheniformis and B. subtilis demonstrate srf gene; nevertheless, sfp gene was expressed only by Bacillus subtilis.
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25
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Rocha LL, Colares GB, Angelim AL, Grangeiro TB, Melo VMM. Culturable populations of Acinetobacter can promptly respond to contamination by alkanes in mangrove sediments. Mar Pollut Bull 2013; 76:214-219. [PMID: 24050127 DOI: 10.1016/j.marpolbul.2013.08.040] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [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: 08/06/2013] [Accepted: 08/26/2013] [Indexed: 06/02/2023]
Abstract
This study evaluated the potential of bacterial isolates from mangrove sediments to degrade hexadecane, an paraffin hydrocarbon that is a large constituent of diesel and automobile lubricants. From a total of 18 oil-degrading isolates obtained by an enrichment technique, four isolates showed a great potential to degrade hexadecane. The strain MSIC01, which was identified by 16S rRNA gene sequencing as Acinetobacter sp., showed the best performance in degrading this hydrocarbon, being capable of completely degrading 1% (v/v) hexadecane within 48 h without releasing biosurfactants. Its hydrophobic surface probably justifies its potential to degrade high concentrations of hexadecane. Thus, the sediments from the studied mangrove harbour bacterial communities that are able to use oil as a carbon source, which is a particularly interesting feature due to the risk of oil spills in coastal areas. Moreover, Acinetobacter sp. MSIC01 emerged as a promising candidate for applications in bioremediation of contaminated mangrove sediments.
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Affiliation(s)
- Lidianne L Rocha
- Laboratório de Ecologia Microbiana e Biotecnologia (LEMBiotech), Departamento de Biologia, Universidade Federal do Ceará, Av. Humberto Monte, 2977, Campus do Pici, Bloco 909, 60455-000 Fortaleza, Ceará, Brazil
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26
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Orsinger-Jacobsen SJ, Patel SS, Vellozzi EM, Gialanella P, Nimrichter L, Miranda K, Martinez LR. Use of a stainless steel washer platform to study Acinetobacter baumannii adhesion and biofilm formation on abiotic surfaces. Microbiology (Reading) 2013; 159:2594-2604. [PMID: 24025603 DOI: 10.1099/mic.0.068825-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Acinetobacter baumannii is a frequent cause of hospital-acquired pneumonia, and has recently increased in incidence as the causative agent of severe disease in troops wounded in Afghanistan and Iraq. Clinical approaches are limited since A. baumannii strains isolated from patients are extremely resistant to current antimicrobials. A. baumannii can survive desiccation and during outbreaks has been recovered from various sites in the patients' environment. To better understand its prevalence in hospital settings, we used a stainless steel washer (SSW) platform to investigate A. baumannii biofilm formation on abiotic surfaces. Scanning electron microscopy demonstrated that A. baumannii forms strong biofilms on stainless steel surfaces. This platform was combined with a colorimetric 2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-5-[(phenylamino)carbonyl]-2H-tetrazolium hydroxide (XTT) reduction assay to observe the metabolic activity of bacterial cells, and to facilitate the manipulation and comparison of multiple A. baumannii clinical strains. A strong correlation between XTT and c.f.u. assays was demonstrated. To complement the cell viability assays, A. baumannii biofilm mass was measured by crystal violet staining. Furthermore, the effect of commonly used disinfectants and environmental stressors on A. baumannii biofilms and planktonic cells was compared and characterized. Biofilms on SSWs were significantly more resistant than their planktonic counterparts, providing additional evidence that may allow us to understand the high prevalence of this microbe in hospital settings. Our results validate that SSWs are a simple, versatile and innovative method to study A. baumannii biofilms in vitro.
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Affiliation(s)
| | - Shenan S Patel
- Department of Biomedical Sciences, Long Island University-Post, Brookville, NY, USA
| | - Ernestine M Vellozzi
- Department of Biomedical Sciences, Long Island University-Post, Brookville, NY, USA
| | | | - Leonardo Nimrichter
- Instituto de Microbiologia Professor Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Kildare Miranda
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Luis R Martinez
- Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, NY, USA.,Departments of Medicine, Division of Infectious Diseases, Albert Einstein College of Medicine, Bronx, NY, USA.,Department of Biomedical Sciences, Long Island University-Post, Brookville, NY, USA
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27
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Kim J, Park W. Indole inhibits bacterial quorum sensing signal transmission by interfering with quorum sensing regulator folding. Microbiology (Reading) 2013; 159:2616-2625. [PMID: 24025605 DOI: 10.1099/mic.0.070615-0] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Quorum sensing (QS)-dependent biofilm formation and motility were controlled by AqsR in Acinetobacter oleivorans DR1. QS-controlled phenotypes appeared to be inhibited by indole and the aqsR mutant had the same phenotypes. We demonstrated that the turnover rate of AqsR became more rapid without the N-acylhomoserine lactone (AHL) signal, and that indole could increase the expression of many protease and chaperone proteins. The addition of exogenous indole decreased the expression of two AqsR-targeted genes: AOLE_03905 (putative surface adhesion protein) and AOLE_11355 (L-asparaginase). The overexpression of AqsR in Escherichia coli was impossible with the indole treatment. Surprisingly, our [(35)S]methionine pulse-labelling data demonstrated that the stability and folding of AqsR protein decreased in the presence of indole without changing aqsR mRNA expression in E. coli. Interestingly, indole resulted in a loss of TraR-dependent traG expression in an Agrobacterium tumefaciens indicator strain. However, when indole was added after incubation with exogenous AHL, indole could not inhibit the TraR-dependent expression of the traG promoter. This indicated that AHL-bound TraR could be protective against indole, but TraR without AHL could not be active in the presence of indole. Here, we provided evidence for the first time showing that the indole effect on QS-controlled bacterial phenotypes is due to inhibited QS regulator folding and not a reduced QS signal.
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Affiliation(s)
- Jisun Kim
- Department of Environmental Science and Ecological Engineering, Korea University, Seoul 136-713, Republic of Korea
| | - Woojun Park
- Department of Environmental Science and Ecological Engineering, Korea University, Seoul 136-713, Republic of Korea
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28
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Goh S, Zhang Q, Zhang J, Mcdougald D, Krantz WB, Liu Y, Fane AG. Impact of a biofouling layer on the vapor pressure driving force and performance of a membrane distillation process. J Memb Sci 2013; 438:140-52. [DOI: 10.1016/j.memsci.2013.03.023] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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29
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Soon RL, Li J, Boyce JD, Harper M, Adler B, Larson I, Nation RL. Cell surface hydrophobicity of colistin-susceptible vs resistant Acinetobacter baumannii determined by contact angles: methodological considerations and implications. J Appl Microbiol 2013; 113:940-51. [PMID: 22574702 DOI: 10.1111/j.1365-2672.2012.05337.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Contact angle analysis of cell surface hydrophobicity (CSH) describes the tendency of a water droplet to spread across a lawn of filtered bacterial cells. Colistin-induced disruption of the Gram-negative outer membrane necessitates hydrophobic contacts with lipopolysaccharide (LPS). We aimed to characterize the CSH of Acinetobacter baumannii using contact angles, to provide insight into the mechanism of colistin resistance. Contact angles were analysed for five paired colistin-susceptible and resistant Ac. baumannii strains. Drainage of the water droplet through bacterial layers was demonstrated to influence results. Consequently, measurements were performed 0·66s after droplet deposition. Colistin-resistant cells exhibited lower contact angles (38·8±2·8-46·8±1·3°) compared with their paired colistin-susceptible strains (40·7±3·0-48·0±1·4°; anova; P<0·05). Contact angles increased at stationary phase (50·3±2·9-61·5±2·5° and 47·4±2·0-50·8±3·2°, susceptible and resistant, respectively, anova; P<0·05) and in response to colistin 32mgl(-1) exposure (44·5±1·5-50·6±2·8° and 43·5±2·2-48·0±2·2°, susceptible and resistant, respectively; anova; P<0·05). Analysis of complemented strains constructed with an intact lpxA gene, or empty vector, highlighted the contribution of LPS to CSH. Compositional outer-membrane variations likely account for CSH differences between Ac. baumannii phenotypes, which influence the hydrophobic colistin-bacterium interaction. Important insight into the mechanism of colistin resistance has been provided. Greater consideration of contact angle methodology is necessary to ensure accurate analyses are performed.
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Affiliation(s)
- R L Soon
- Facility for Anti-infective Drug Development and Innovation, Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Vic., Australia
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30
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Kim J, Park W. Identification and characterization of genes regulated by AqsR, a LuxR-type regulator in Acinetobacter oleivorans DR1. Appl Microbiol Biotechnol 2013; 97:6967-78. [DOI: 10.1007/s00253-013-5006-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2013] [Revised: 05/09/2013] [Accepted: 05/17/2013] [Indexed: 12/25/2022]
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31
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Nandakumar V, Chittaranjan S, Kurian VM, Doble M. Characteristics of bacterial biofilm associated with implant material in clinical practice. Polym J 2012. [DOI: 10.1038/pj.2012.130] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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32
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Phuong K, Hanazaki S, Kakii K, Nikata T. Involvement of Acinetobacter sp. in the floc-formation in activated sludge process. J Biotechnol 2012; 157:505-11. [DOI: 10.1016/j.jbiotec.2011.09.024] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2011] [Revised: 09/02/2011] [Accepted: 09/22/2011] [Indexed: 11/16/2022]
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33
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Abbasnezhad H, Gray M, Foght JM. Influence of adhesion on aerobic biodegradation and bioremediation of liquid hydrocarbons. Appl Microbiol Biotechnol 2011; 92:653-75. [DOI: 10.1007/s00253-011-3589-4] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2011] [Revised: 08/27/2011] [Accepted: 09/15/2011] [Indexed: 01/14/2023]
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Jung J, Noh J, Park W. Physiological and metabolic responses for hexadecane degradation in Acinetobacter oleivorans DR1. J Microbiol 2011; 49:208-15. [PMID: 21538240 DOI: 10.1007/s12275-011-0395-8] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2010] [Accepted: 12/10/2010] [Indexed: 11/30/2022]
Abstract
The hexadecane degradation of Acinetobacter oleivorans DR1 was evaluated with changes in temperature and ionic salt contents. Hexadecane degradation of strain DR1 was reduced markedly by the presence of sodium chloride (but not potassium chloride). High temperature (37°C) was also shown to inhibit the motility, biofilm formation, and hexadecane biodegradation. The biofilm formation of strain DR1 on the oil-water interface might prove to be a critical physiological feature for the degradation of hexadecane. The positive relationship between biofilm formation and hexadecane degradation could be observed at 30° C, but not at low temperatures (25°C). Alterations in cell hydrophobicity and EPS production by temperature and salts were not correlated with biofilm formation and hexadecane degradation. Our proteomic analyses have demonstrated that metabolic changes through the glyoxylate pathway are important for efficient degradation of hexadecane. Proteins involved in fatty acid metabolism, gluconeogenesis, and oxidative stress defense proteins appear to be highly expressed during biodegradation of hexadecane. These results suggested that biofilm formation and oxidative stress defense are important physiological responses for hexadecane degradation along with metabolic switch to glyoxylate pathway in strain DR1.
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Affiliation(s)
- Jaejoon Jung
- Division of Environmental Science and Ecological Engineering, Korea University, Seoul 136-713, Republic of Korea
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35
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Lee Y, Seo H, Yeom J, Park W. Molecular characterization of the extracellular matrix in a Pseudomonas putida dsbA mutant: implications for acidic stress defense and plant growth promotion. Res Microbiol 2011; 162:302-10. [DOI: 10.1016/j.resmic.2010.11.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2010] [Accepted: 10/12/2010] [Indexed: 11/27/2022]
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Abstract
AIMS To investigate roles of quorum-sensing (QS) system in Acinetobacter sp. strain DR1 and rifampicin-resistant variant (hereinafter DR1R). METHODS AND RESULTS The DR1 strain generated three putative acyl homoserine lactones (AHLs), while the DR1R produced only one signal and QS signal production was abrogated in the aqsI (LuxI homolog) mutant. The hexadecane-degradation and biofilm-formation capabilities of DR1, DR1R, and aqsI mutants were compared, along with their proteomic data. Proteomics analysis revealed that the AHL lactonase responsible for degrading QS signal was highly upregulated in both DR1R and aqsI mutant, also showed that several proteins, including ppGpp synthase, histidine kinase sensors, might be under the control of QS signalling. Interestingly, biofilm-formation and hexadecane-biodegradation abilities were reduced more profoundly in the aqsI mutant. These altered phenotypes of the aqsI mutant were restored via the addition of free wild-type cell supernatant and exogenous C(12) -AHL. CONCLUSIONS The QS system in strain DR1 contributes to hexadecane degradation and biofilm formation. SIGNIFICANCE AND IMPACT OF THE STUDY This is the first report to demonstrate that a specific QS signal appears to be a critical factor for hexadecane degradation and biofilm formation in Acinetobacter sp. strain DR1.
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Affiliation(s)
- Y-S Kang
- Division of Environmental Science and Ecological Engineering, Korea University, Seoul, Korea
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Abstract
Rifampicin, a bactericidal antibiotic drug, is routinely used to make an environmental recipient selective in laboratory-conjugation experiments. We noticed, inadvertently, that the rifampicin-resistant Acinetobacter sp. strain DR1, a recently discovered hexadecane-degrading environmental isolate, exhibited a substantial loss of quorum sensing signalling. The domesticated ampicillin-resistant strain, DR1, evidenced more dramatic phenotypic changes than were observed in the rifampicin-resistant cells: a complete loss of quorum sensing, a loss in swimming and swarming motilities, poor fimbrial expression, increased rigidity in membrane fatty acid composition and reduced hexadecane degradation capability. Interestingly, the motility of strain DR1 grown adjacent to a streptomycin-producing Streptomyces griceus was permanently abrogated, where this change was heritable and other phenotypic changes could not be detected. In this study, we have reported for the first time that the in situ acquisition of antibiotic resistance may reduce biological fitness, including losses in the production of quorum sensing signals, motility and substrate utilization, and each antibiotic is associated with different degrees of phenotypic and genetic alterations. Our data also suggested that the domestication of environmental isolates should be approached with caution, as there are phenotypic variations in antibiotic-resistant cells that might not be noticeable unless all possible phenotypic assays are conducted.
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Affiliation(s)
- Yoon-Suk Kang
- Division of Environmental Science and Ecological Engineering, Korea University, Seoul, Korea
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de Breij A, Gaddy J, van der Meer J, Koning R, Koster A, van den Broek P, Actis L, Nibbering P, Dijkshoorn L. CsuA/BABCDE-dependent pili are not involved in the adherence of Acinetobacter baumannii ATCC19606T to human airway epithelial cells and their inflammatory response. Res Microbiol 2009; 160:213-8. [DOI: 10.1016/j.resmic.2009.01.002] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Phuong K, Kakii K, Nikata T. Intergeneric coaggregation of non-flocculating Acinetobacter spp. isolates with other sludge-constituting bacteria. J Biosci Bioeng 2009; 107:394-400. [DOI: 10.1016/j.jbiosc.2008.11.020] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2008] [Accepted: 11/22/2008] [Indexed: 01/09/2023]
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Maier RM. Microorganisms and Organic Pollutants. Environ Microbiol 2009. [DOI: 10.1016/b978-0-12-370519-8.00020-1] [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: 03/03/2023]
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Obuekwe C, Al-Jadi Z, Al-Saleh E. Comparative hydrocarbon utilization by hydrophobic and hydrophilic variants ofPseudomonas aeruginosa. J Appl Microbiol 2008; 105:1876-87. [DOI: 10.1111/j.1365-2672.2008.03887.x] [Citation(s) in RCA: 21] [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: 11/29/2022]
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Dorobantu LS, Bhattacharjee S, Foght JM, Gray MR. Atomic force microscopy measurement of heterogeneity in bacterial surface hydrophobicity. Langmuir 2008; 24:4944-4951. [PMID: 18355095 DOI: 10.1021/la7035295] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The structure and physicochemical properties of microbial surfaces at the molecular level determine their adhesion to surfaces and interfaces. Here, we report the use of atomic force microscopy (AFM) to explore the morphology of soft, living cells in aqueous buffer, to map bacterial surface heterogeneities, and to directly correlate the results in the AFM force-distance curves to the macroscopic properties of the microbial surfaces. The surfaces of two bacterial species, Acinetobacter venetianus RAG-1 and Rhodococcus erythropolis 20S-E1-c, showing different macroscopic surface hydrophobicity were probed with chemically functionalized AFM tips, terminating in hydrophobic and hydrophilic groups. All force measurements were obtained in contact mode and made on a location of the bacterium selected from the alternating current mode image. AFM imaging revealed morphological details of the microbial-surface ultrastructures with about 20 nm resolution. The heterogeneous surface morphology was directly correlated with differences in adhesion forces as revealed by retraction force curves and also with the presence of external structures, either pili or capsules, as confirmed by transmission electron microscopy. The AFM force curves for both bacterial species showed differences in the interactions of extracellular structures with hydrophilic and hydrophobic tips. A. venetianus RAG-1 showed an irregular pattern with multiple adhesion peaks suggesting the presence of biopolymers with different lengths on its surface. R. erythropolis 20S-E1-c exhibited long-range attraction forces and single rupture events suggesting a more hydrophobic and smoother surface. The adhesion force measurements indicated a patchy surface distribution of interaction forces for both bacterial species, with the highest forces grouped at one pole of the cell for R. erythropolis 20S-E1-c and a random distribution of adhesion forces in the case of A. venetianus RAG-1. The magnitude of the adhesion forces was proportional to the three-phase contact angle between hexadecane and water on the bacterial surfaces.
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Affiliation(s)
- Loredana S Dorobantu
- Department of Chemical and Materials Engineering, University of Alberta, Edmonton, Alberta T6G 2G6, Canada
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Kang Z, Yeung A, Foght JM, Gray MR. Mechanical properties of hexadecane–water interfaces with adsorbed hydrophobic bacteria. Colloids Surf B Biointerfaces 2008; 62:273-9. [PMID: 18093811 DOI: 10.1016/j.colsurfb.2007.10.021] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2007] [Revised: 09/18/2007] [Accepted: 10/25/2007] [Indexed: 11/27/2022]
Affiliation(s)
- Zhewen Kang
- Department of Chemical and Materials Engineering, University of Alberta, Edmonton, Alberta, Canada
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Obuekwe CO, Al-Jadi ZK, Al-Saleh E. Insight into heterogeneity in cell-surface hydrophobicity and ability to degrade hydrocarbons among cells of two hydrocarbon-degrading bacterial populations. Can J Microbiol 2007; 53:252-60. [PMID: 17496974 DOI: 10.1139/w06-115] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The sequential bacterial adherence to hydrocarbons (BATH) of successive generations of hydrophobic fractions of Paenibacillus sp. R0032A and Burkholderia cepacia gave rise to bacterial populations of increasing cell-surface hydrophobicity. Thus, hydrophobicity of the first generation (H1) was less than that of the second generation (H2), which was less than that of the third generation (H3). Beyond H3, the hydrophobic populations became less stable and tended to lyse in hexadecane after violent (vortex) agitation, resulting in an apparent decline in BATH value. The exhaustively fractionated aqueous-phase population (L) was very hydrophilic. The overall cell-surface distribution of the population was L < parental strain < H1 < H2 < H3. The ability to degrade crude oil, hexadecane, or phenanthrene matched the degree of cell-surface hydrophobicity: L < P < H1 < H2 < H3. Thus, in natural populations of hydrocarbon-degrading Paenibacillus sp. R0032A and B. cepacia, there is a heterogeneity in the hydrophobic surface characteriistics that affects the ability of cells to use various hydrocarbon substrates.
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Affiliation(s)
- Christian O Obuekwe
- Division of Microbiology, Department of Biological Sciences, Faculty of Science, Kuwait University, P.O. Box 5969, Safat 13060, Kuwait.
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Wentzel A, Ellingsen TE, Kotlar HK, Zotchev SB, Throne-Holst M. Bacterial metabolism of long-chain n-alkanes. Appl Microbiol Biotechnol 2007; 76:1209-21. [PMID: 17673997 DOI: 10.1007/s00253-007-1119-1] [Citation(s) in RCA: 207] [Impact Index Per Article: 12.2] [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: 04/29/2007] [Revised: 07/10/2007] [Accepted: 07/11/2007] [Indexed: 10/23/2022]
Abstract
Degradation of alkanes is a widespread phenomenon in nature, and numerous microorganisms, both prokaryotic and eukaryotic, capable of utilizing these substrates as a carbon and energy source have been isolated and characterized. In this review, we summarize recent advances in the understanding of bacterial metabolism of long-chain n-alkanes. Bacterial strategies for accessing these highly hydrophobic substrates are presented, along with systems for their enzymatic degradation and conversion into products of potential industrial value. We further summarize the current knowledge on the regulation of bacterial long-chain n-alkane metabolism and survey progress in understanding bacterial pathways for utilization of n-alkanes under anaerobic conditions.
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Affiliation(s)
- Alexander Wentzel
- Department of Biotechnology, Norwegian University of Science and Technology, Sem Saelandsvei 6/8, 7491 Trondheim, Norway.
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Klein AN, Frigon D, Raskin L. Populations related to Alkanindiges, a novel genus containing obligate alkane degraders, are implicated in biological foaming in activated sludge systems. Environ Microbiol 2007; 9:1898-912. [PMID: 17635538 DOI: 10.1111/j.1462-2920.2007.01307.x] [Citation(s) in RCA: 22] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Activated sludge mixed liquor and biological foam samples were collected from five full-scale municipal wastewater treatment plants in Illinois, all of which were exhibiting biological foaming at the time of sampling. Oligonucleotide probe hybridization consistently measured higher levels of Gammaproteobacteria rRNA in the foam as compared with the mixed liquor for all treatment plants analysed. Cloning and sequencing of 16S rRNA gene amplicons led to the identification of populations which were abundant in each of the treatment plants. These populations were related to the Alkanindiges/Acinetobacter cluster within the Gammaproteobacteria. Further analysis of the 16S rRNA sequences indicated that they clustered in three phylogenetic groups outside the main Alkanindiges/Acinetobacter cluster, suggesting that these groups may represent new taxa. Terminal-restriction fragment length polymorphism analysis showed that these populations were enriched in the foam compared with the underlying mixed liquor similar to the enrichment of the Gammaproteobacteria measured by oligonucleotide probe membrane hybridization. The observed enrichment in foam samples is suggestive of a role for these populations in foam formation or stabilization, and their presence in all treatment plants analysed in this study may be indicative of their widespread abundance in foaming plants.
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Affiliation(s)
- Adam N Klein
- Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
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Obuekwe CO, Al-Jadi ZK, Al-Saleh ES. Sequential hydrophobic partitioning of cells ofPseudomonas aeruginosagives rise to variants of increasing cell-surface hydrophobicity. FEMS Microbiol Lett 2007; 270:214-9. [PMID: 17391374 DOI: 10.1111/j.1574-6968.2007.00685.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
The partitioning of bacterial cells in a dual aqueous-solvent phase system leads to separation into 'hydrophilic' and hydrophobic functions. Sequential multistep partitioning, accompanied by successive enrichment, gives rise to several cycles of hydrophobic and hydrophilic cell populations which possess different cell-surface hydrophobicity characteristics. Characterization of the cell-surface hydrophobicity by several methods (salting-out aggregation test, bacterial adherence to hydrocarbon, polystyrene binding and hydrophobic interaction chromatography) was carried out. The cell-surface hydrophobicity varied in the order: hydrophilic fraction < parental strain < first cycle hydrophobic variant < second cycle hydrophobic variant < third cycle hydrophobic variant. Electron microscopy showed that the most hydrophobic variant was densely covered by hydrophobic structures - fimbriae - whereas the parental strain was covered by a mixture of surface structures. The hydrophilic variant was covered by an amorphous exopolymeric substance, which is a polysaccharide, shown by its reaction with Alcian blue.
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Affiliation(s)
- Christian O Obuekwe
- Microbiology Division, Department of Biological Sciences, Faculty of Science, Kuwait University, Kuwait City, Kuwait.
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Abstract
Acinetobacter venetianus Rag1 produces an extracellular, polymeric lipoheteropolysaccharide termed apoemulsan. This polymer is putatively produced via a Wzy-dependent pathway. According to this model, the length of the polymer is regulated by polysaccharide-copolymerase (PCP) protein. A highly conserved proline and glycine motif was identified in all members of the PCP family of proteins and is involved in regulation of polymer chain length. In order to control the structure of apoemulsan, defined point mutations in the proline-glycine-rich region of the apoemulsan PCP protein (Wzc) were introduced. Modified wzc variants were introduced into the Rag1 genome via homologous recombination. Stable chromosomal mutants were confirmed by Southern blot analysis. The molecular weight of the polymer was analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Five of the eight point mutants produced polymers having molecular weights higher than the molecular weight of the polymer produced by the wild type. Moreover, four of these five polymers had modified biological properties. Replacement of arginine by leucine (R418L) resulted in the most significant change in the molecular weight of the polymer. The R418L mutant was the most hydrophilic mutant, exhibiting decreased adherence to polystyrene, and inhibited biofilm formation. The results described in this report show the functional effect of Wzc modification on the molecular weight of a high-molecular-weight polysaccharide. Moreover, in the present study we developed a genetic system to control polymerization of apoemulsan. The use of selective exogenous fatty acid feeding strategies, as well as genetic manipulation of sugar backbone chain length, is a promising new approach for bioengineering emulsan analogs.
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Affiliation(s)
- Hanna Dams-Kozlowska
- Tufts University, Department of Biomedical Engineering, 4 Colby St., Rm. 153, Medford, MA 02155, USA
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