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Suarez C, Rosenqvist T, Dimitrova I, Sedlacek CJ, Modin O, Paul CJ, Hermansson M, Persson F. Biofilm colonization and succession in a full-scale partial nitritation-anammox moving bed biofilm reactor. Microbiome 2024; 12:51. [PMID: 38475926 DOI: 10.1186/s40168-024-01762-8] [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] [Subscribe] [Scholar Register] [Received: 03/29/2023] [Accepted: 01/09/2024] [Indexed: 03/14/2024]
Abstract
BACKGROUND Partial nitritation-anammox (PNA) is a biological nitrogen removal process commonly used in wastewater treatment plants for the treatment of warm and nitrogen-rich sludge liquor from anaerobic digestion, often referred to as sidestream wastewater. In these systems, biofilms are frequently used to retain biomass with aerobic ammonia-oxidizing bacteria (AOB) and anammox bacteria, which together convert ammonium to nitrogen gas. Little is known about how these biofilm communities develop, and whether knowledge about the assembly of biofilms in natural communities can be applied to PNA biofilms. RESULTS We followed the start-up of a full-scale PNA moving bed biofilm reactor for 175 days using shotgun metagenomics. Environmental filtering likely restricted initial biofilm colonization, resulting in low phylogenetic diversity, with the initial microbial community comprised mainly of Proteobacteria. Facilitative priority effects allowed further biofilm colonization, with the growth of initial aerobic colonizers promoting the arrival and growth of anaerobic taxa like methanogens and anammox bacteria. Among the early colonizers were known 'oligotrophic' ammonia oxidizers including comammox Nitrospira and Nitrosomonas cluster 6a AOB. Increasing the nitrogen load in the bioreactor allowed colonization by 'copiotrophic' Nitrosomonas cluster 7 AOB and resulted in the exclusion of the initial ammonia- and nitrite oxidizers. CONCLUSIONS We show that complex dynamic processes occur in PNA microbial communities before a stable bioreactor process is achieved. The results of this study not only contribute to our knowledge about biofilm assembly and PNA bioreactor start-up but could also help guide strategies for the successful implementation of PNA bioreactors. Video Abstract.
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Affiliation(s)
- Carolina Suarez
- Division of Water Resources Engineering, Faculty of Engineering LTH, Lund University, Lund, Sweden.
- Department of Chemistry and Molecular Biology, University of Gothenburg, Gothenburg, Sweden.
| | - Tage Rosenqvist
- Division of Applied Microbiology, Department of Chemistry, Lund University, Lund, Sweden
| | | | - Christopher J Sedlacek
- Division of Microbial Ecology, Centre for Microbiology and Environmental Systems Science, University of Vienna, Vienna, Austria
| | - Oskar Modin
- Division of Water Environment Technology, Department of Architecture and Civil Engineering, Chalmers University of Technology, Gothenburg, Sweden
| | - Catherine J Paul
- Division of Water Resources Engineering, Faculty of Engineering LTH, Lund University, Lund, Sweden
- Division of Applied Microbiology, Department of Chemistry, Lund University, Lund, Sweden
| | - Malte Hermansson
- Department of Chemistry and Molecular Biology, University of Gothenburg, Gothenburg, Sweden
| | - Frank Persson
- Division of Water Environment Technology, Department of Architecture and Civil Engineering, Chalmers University of Technology, Gothenburg, Sweden
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Liébana R, Modin O, Persson F, Hermansson M, Wilén BM. Resistance of aerobic granular sludge microbiomes to periodic loss of biomass. Biofilm 2023; 6:100145. [PMID: 37575957 PMCID: PMC10415711 DOI: 10.1016/j.bioflm.2023.100145] [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: 04/14/2023] [Revised: 07/07/2023] [Accepted: 07/26/2023] [Indexed: 08/15/2023] Open
Abstract
Granular sludge is a biofilm process used for wastewater treatment which is currently being implemented worldwide. It is important to understand how disturbances affect the microbial community and performance of reactors. Here, two acetate-fed replicate reactors were inoculated with acclimatized sludge and the reactor performance, and the granular sludge microbial community succession were studied for 149 days. During this time, the microbial community was challenged by periodically removing half of the reactor biomass, subsequently increasing the food-to-microorganism (F/M) ratio. Diversity analysis together with null models show that overall, the microbial communities were resistant to the disturbances, observing some minor effects on polyphosphate-accumulating and denitrifying microbial communities and their associated reactor functions. Community turnover was driven by drift and random granule loss, and stochasticity was the governing ecological process for community assembly. These results evidence the aerobic granular sludge process as a robust system for wastewater treatment.
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Affiliation(s)
- Raquel Liébana
- Division of Water Environment Technology, Department of Architecture and Civil Engineering, Chalmers University of Technology, Sven Hultins gata 6, SE 412 96, Gothenburg, Sweden
- AZTI, Marine Research Division, Basque Research Technology Alliance (BRTA), Txatxarramendi Ugartea z/g, 48395, Sukarrieta, Bizkaia, Spain
| | - Oskar Modin
- Division of Water Environment Technology, Department of Architecture and Civil Engineering, Chalmers University of Technology, Sven Hultins gata 6, SE 412 96, Gothenburg, Sweden
| | - Frank Persson
- Division of Water Environment Technology, Department of Architecture and Civil Engineering, Chalmers University of Technology, Sven Hultins gata 6, SE 412 96, Gothenburg, Sweden
| | - Malte Hermansson
- Department of Chemistry and Molecular Biology, University of Gothenburg, Medicinaregatan 9E, SE-413 90, Gothenburg, Sweden
| | - Britt-Marie Wilén
- Division of Water Environment Technology, Department of Architecture and Civil Engineering, Chalmers University of Technology, Sven Hultins gata 6, SE 412 96, Gothenburg, Sweden
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Äikäs L, Hermansson M, Holopainen M, Ruhanen H, Käkelä R, Kovanen P, Öörni K. Icosapent ethyl supplementation rapidly and transiently alters the composition and functionality of circulating lipoproteins in humans. Atherosclerosis 2022. [DOI: 10.1016/j.atherosclerosis.2022.06.454] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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Suarez C, Sedlacek CJ, Gustavsson DJI, Eiler A, Modin O, Hermansson M, Persson F. Disturbance-based management of ecosystem services and disservices in partial nitritation-anammox biofilms. NPJ Biofilms Microbiomes 2022; 8:47. [PMID: 35676296 PMCID: PMC9178042 DOI: 10.1038/s41522-022-00308-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Accepted: 05/13/2022] [Indexed: 11/28/2022] Open
Abstract
The resistance and resilience provided by functional redundancy, a common feature of microbial communities, is not always advantageous. An example is nitrite oxidation in partial nitritation-anammox (PNA) reactors designed for nitrogen removal in wastewater treatment, where suppression of nitrite oxidizers like Nitrospira is sought. In these ecosystems, biofilms provide microhabitats with oxygen gradients, allowing the coexistence of aerobic and anaerobic bacteria. We designed a disturbance experiment where PNA biofilms, treating water from a high-rate activated sludge process, were constantly or intermittently exposed to anaerobic sidestream wastewater, which has been proposed to inhibit nitrite oxidizers. With increasing sidestream exposure we observed decreased abundance, alpha-diversity, functional versatility, and hence functional redundancy, among Nitrospira in the PNA biofilms, while the opposite patterns were observed for anammox bacteria within Brocadia. At the same time, species turnover was observed for aerobic ammonia-oxidizing Nitrosomonas populations. The different exposure regimens were associated with metagenomic assembled genomes of Nitrosomonas, Nitrospira, and Brocadia, encoding genes related to N-cycling, substrate usage, and osmotic stress response, possibly explaining the three different patterns by niche differentiation. These findings imply that disturbances can be used to manage the functional redundancy of biofilm microbiomes in a desirable direction, which should be considered when designing operational strategies for wastewater treatment.
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Suarez C, Dalcin Martins P, Jetten M, Karačić S, Wilén BM, Modin O, Hagelia P, Hermansson M, Persson F. Metagenomic evidence of a novel family of anammox bacteria in a subsea environment. Environ Microbiol 2022; 24:2348-2360. [PMID: 35415863 PMCID: PMC9325076 DOI: 10.1111/1462-2920.16006] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [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: 12/07/2021] [Accepted: 04/07/2022] [Indexed: 12/02/2022]
Abstract
Bacteria in the order ‘Candidatus Brocadiales’ within the phylum Planctomycetes (Planctomycetota) have the remarkable ability to perform anaerobic ammonium oxidation (anammox). Two families of anammox bacteria with different biogeographical distributions have been reported, marine Ca. Scalinduaceae and freshwater Ca. Brocadiaceae. Here we report evidence of three new species within a novel genus and family of anammox bacteria, which were discovered in biofilms of a subsea road tunnel under a fjord in Norway. In this particular ecosystem, the nitrogen cycle is likely fuelled by ammonia from organic matter degradation in the fjord sediments and the rock mass above the tunnel, resulting in the growth of biofilms where anammox bacteria can thrive under oxygen limitation. We resolved several metagenome‐assembled genomes (MAGs) of anammox bacteria, including three Ca. Brocadiales MAGs that could not be classified at the family level. MAGs of this novel family had all the diagnostic genes for a full anaerobic ammonium oxidation pathway in which nitrite was probably reduced by a NirK‐like reductase. A survey of published molecular data indicated that this new family of anammox bacteria occurs in many marine sediments, where its members presumably would contribute to nitrogen loss.
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Affiliation(s)
- Carolina Suarez
- Division of Water Resources Engineering, Faculty of Engineering LTH, Lund University, Lund, Sweden.,Department of Chemistry and Molecular Biology, University of Gothenburg, Gothenburg, Sweden
| | - Paula Dalcin Martins
- Department of Microbiology, RIBES, Radboud Institute for Biological and Environmental Sciences, Radboud University, Nijmegen, Netherlands
| | - Mike Jetten
- Department of Microbiology, RIBES, Radboud Institute for Biological and Environmental Sciences, Radboud University, Nijmegen, Netherlands
| | - Sabina Karačić
- Division of Water Environment Technology, Department of Architecture and Civil Engineering, Chalmers University of Technology, Gothenburg, Sweden
| | - Britt Marie Wilén
- Division of Water Environment Technology, Department of Architecture and Civil Engineering, Chalmers University of Technology, Gothenburg, Sweden
| | - Oskar Modin
- Division of Water Environment Technology, Department of Architecture and Civil Engineering, Chalmers University of Technology, Gothenburg, Sweden
| | - Per Hagelia
- Construction Division, The Norwegian Public Roads Administration, Oslo, Norway
| | - Malte Hermansson
- Department of Chemistry and Molecular Biology, University of Gothenburg, Gothenburg, Sweden
| | - Frank Persson
- Division of Water Environment Technology, Department of Architecture and Civil Engineering, Chalmers University of Technology, Gothenburg, Sweden
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Lorey M, Borelli M, Äikäs L, Youssef A, Hermansson M, Kemppainen A, Ruhanen H, Ruuth M, Matikainen S, Kovanen P, Käkelä R, Boffa M, Koschinsky M, Öörni K. Lp(a) induces inflammasome activation in human macrophages. Atherosclerosis 2021. [DOI: 10.1016/j.atherosclerosis.2021.06.061] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Modin O, Liébana R, Saheb-Alam S, Wilén BM, Suarez C, Hermansson M, Persson F. Correction to: Hill-based dissimilarity indices and null models for analysis of microbial community assembly. Microbiome 2020; 8:148. [PMID: 33115538 PMCID: PMC7594297 DOI: 10.1186/s40168-020-00942-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
An amendment to this paper has been published and can be accessed via the original article.
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Affiliation(s)
- Oskar Modin
- Water Environment Technology, Architecture and Civil Engineering, Chalmers University of Technology, Gothenburg, Sweden.
| | - Raquel Liébana
- Water Environment Technology, Architecture and Civil Engineering, Chalmers University of Technology, Gothenburg, Sweden
| | - Soroush Saheb-Alam
- Water Environment Technology, Architecture and Civil Engineering, Chalmers University of Technology, Gothenburg, Sweden
| | - Britt-Marie Wilén
- Water Environment Technology, Architecture and Civil Engineering, Chalmers University of Technology, Gothenburg, Sweden
| | - Carolina Suarez
- Chemistry and Molecular Biology, University of Gothenburg, Gothenburg, Sweden
| | - Malte Hermansson
- Chemistry and Molecular Biology, University of Gothenburg, Gothenburg, Sweden
| | - Frank Persson
- Water Environment Technology, Architecture and Civil Engineering, Chalmers University of Technology, Gothenburg, Sweden
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Modin O, Liébana R, Saheb-Alam S, Wilén BM, Suarez C, Hermansson M, Persson F. Hill-based dissimilarity indices and null models for analysis of microbial community assembly. Microbiome 2020; 8:132. [PMID: 32917275 PMCID: PMC7488682 DOI: 10.1186/s40168-020-00909-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [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: 06/02/2020] [Accepted: 08/19/2020] [Indexed: 06/10/2023]
Abstract
BACKGROUND High-throughput amplicon sequencing of marker genes, such as the 16S rRNA gene in Bacteria and Archaea, provides a wealth of information about the composition of microbial communities. To quantify differences between samples and draw conclusions about factors affecting community assembly, dissimilarity indices are typically used. However, results are subject to several biases, and data interpretation can be challenging. The Jaccard and Bray-Curtis indices, which are often used to quantify taxonomic dissimilarity, are not necessarily the most logical choices. Instead, we argue that Hill-based indices, which make it possible to systematically investigate the impact of relative abundance on dissimilarity, should be used for robust analysis of data. In combination with a null model, mechanisms of microbial community assembly can be analyzed. Here, we also introduce a new software, qdiv, which enables rapid calculations of Hill-based dissimilarity indices in combination with null models. RESULTS Using amplicon sequencing data from two experimental systems, aerobic granular sludge (AGS) reactors and microbial fuel cells (MFC), we show that the choice of dissimilarity index can have considerable impact on results and conclusions. High dissimilarity between replicates because of random sampling effects make incidence-based indices less suited for identifying differences between groups of samples. Determining a consensus table based on count tables generated with different bioinformatic pipelines reduced the number of low-abundant, potentially spurious amplicon sequence variants (ASVs) in the data sets, which led to lower dissimilarity between replicates. Analysis with a combination of Hill-based indices and a null model allowed us to show that different ecological mechanisms acted on different fractions of the microbial communities in the experimental systems. CONCLUSIONS Hill-based indices provide a rational framework for analysis of dissimilarity between microbial community samples. In combination with a null model, the effects of deterministic and stochastic community assembly factors on taxa of different relative abundances can be systematically investigated. Calculations of Hill-based dissimilarity indices in combination with a null model can be done in qdiv, which is freely available as a Python package ( https://github.com/omvatten/qdiv ). In qdiv, a consensus table can also be determined from several count tables generated with different bioinformatic pipelines. Video Abstract.
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Affiliation(s)
- Oskar Modin
- Water Environment Technology, Architecture and Civil Engineering, Chalmers University of Technology, Gothenburg, Sweden
| | - Raquel Liébana
- Water Environment Technology, Architecture and Civil Engineering, Chalmers University of Technology, Gothenburg, Sweden
| | - Soroush Saheb-Alam
- Water Environment Technology, Architecture and Civil Engineering, Chalmers University of Technology, Gothenburg, Sweden
| | - Britt-Marie Wilén
- Water Environment Technology, Architecture and Civil Engineering, Chalmers University of Technology, Gothenburg, Sweden
| | - Carolina Suarez
- Chemistry and Molecular Biology, University of Gothenburg, Gothenburg, Sweden
| | - Malte Hermansson
- Chemistry and Molecular Biology, University of Gothenburg, Gothenburg, Sweden
| | - Frank Persson
- Water Environment Technology, Architecture and Civil Engineering, Chalmers University of Technology, Gothenburg, Sweden
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Gustavsson DJI, Suarez C, Wilén BM, Hermansson M, Persson F. Long-term stability of partial nitritation-anammox for treatment of municipal wastewater in a moving bed biofilm reactor pilot system. Sci Total Environ 2020; 714:136342. [PMID: 31982771 DOI: 10.1016/j.scitotenv.2019.136342] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [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: 10/23/2019] [Revised: 12/18/2019] [Accepted: 12/24/2019] [Indexed: 05/21/2023]
Abstract
Nitrogen removal from the mainstream of municipal wastewater with partial nitritation-anammox (PNA) would be highly beneficial with regard to the uses of energy and organic carbon. However, the challenges of process instability, low nitrogen removal rates (NRR) and unwanted aerobic nitrite oxidation need to be solved to reach large-scale implementation. Here, we have operated pilot-scale moving bed biofilm reactors (MBBRs) for mainstream treatment, together with sidestream treatment of sludge liquor from anaerobic digestors, for over 900 days to investigate process stability, reactor performance and microbial community structure at realistic conditions. The MBBR biofilm contained stable and high relative abundances of anammox bacteria (10-32%) consisting of two major Brocadia sp. populations, and several populations of aerobic ammonia-oxidising bacteria (AOB) within Nitrosomonas sp. (0.2-3.1%), as assessed by 16S rDNA amplicon sequencing. In addition, nitrite-oxidising bacteria (NOB) consisting of Nitrospira sp. (0.4-0.8%) and Nitrotoga sp. (up to 0.4%) were present. Nitrogen was removed at a peak rate of 0.66 g N m-2 d-1 (0.13 kg N m-3 d-1) with a nitrate production over ammonium consumption of 15% by the NOB, at operation with continuous aeration at 15 °C. However, during most periods with continuous aeration, the NRR was lower (≈ 0.45 g N m-2 d-1), with larger relative nitrate production (≈40%), presumably due to problems to maintain stable residual ammonium concentrations during wet-weather mainstream flows. Changing reactor operation to intermittent aeration decreased the NRR but did not help in suppressing the NOB. The study shows that with MBBRs, stable mainstream PNA can be attained at realistic NRR, but with need for post-treatment of nitrate, since effective NOB suppression was hard to achieve.
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Affiliation(s)
- David J I Gustavsson
- VA SYD, P.O. Box 191, SE-20121 Malmö, Sweden; Sweden Water Research, c/o Ideon Science Park, Scheelevägen 15, SE-22370 Lund, Sweden
| | - Carolina Suarez
- Department of Chemistry and Molecular Biology, University of Gothenburg, SE-40530 Gothenburg, Sweden; Division of Water Environment Technology, Department of Architecture and Civil Engineering, Chalmers University of Technology, SE-41296 Gothenburg, Sweden
| | - Britt-Marie Wilén
- Division of Water Environment Technology, Department of Architecture and Civil Engineering, Chalmers University of Technology, SE-41296 Gothenburg, Sweden
| | - Malte Hermansson
- Department of Chemistry and Molecular Biology, University of Gothenburg, SE-40530 Gothenburg, Sweden
| | - Frank Persson
- Division of Water Environment Technology, Department of Architecture and Civil Engineering, Chalmers University of Technology, SE-41296 Gothenburg, Sweden.
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Borg D, Sundberg J, Brun E, Kjellén E, Petersson K, Hermansson M, Johansson J, Eberhard J, Johnsson A. PALAESTRA: A phase II trial with short-course radiotherapy followed by chemotherapy as palliative treatment in esophageal adenocarcinoma. Ann Oncol 2019. [DOI: 10.1093/annonc/mdz247.097] [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: 11/15/2022] Open
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Saheb‐Alam S, Persson F, Wilén B, Hermansson M, Modin O. Response to starvation and microbial community composition in microbial fuel cells enriched on different electron donors. Microb Biotechnol 2019; 12:962-975. [PMID: 31228355 PMCID: PMC6680615 DOI: 10.1111/1751-7915.13449] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [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: 12/12/2018] [Revised: 05/21/2019] [Accepted: 05/22/2019] [Indexed: 11/30/2022] Open
Abstract
In microbial fuel cells (MFCs), microorganisms generate electrical current by oxidizing organic compounds. MFCs operated with different electron donors harbour different microbial communities, and it is unknown how that affects their response to starvation. We analysed the microbial communities in acetate- and glucose-fed MFCs and compared their responses to 10 days starvation periods. Each starvation period resulted in a 4.2 ± 1.4% reduction in electrical current in the acetate-fed MFCs and a 10.8 ± 3.9% reduction in the glucose-fed MFCs. When feed was resumed, the acetate-fed MFCs recovered immediately, whereas the glucose-fed MFCs required 1 day to recover. The acetate-fed bioanodes were dominated by Desulfuromonas spp. converting acetate into electrical current. The glucose-fed bioanodes were dominated by Trichococcus sp., functioning as a fermenter, and a member of Desulfuromonadales, using the fermentation products to generate electrical current. Suspended biomass and biofilm growing on non-conductive regions within the MFCs had different community composition than the bioanodes. However, null models showed that homogenizing dispersal of microorganisms within the MFCs affected the community composition, and in the glucose-fed MFCs, the Trichococcus sp. was abundant in all locations. The different responses to starvation can be explained by the more complex pathway requiring microbial interactions to convert glucose into electrical current.
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Affiliation(s)
- Soroush Saheb‐Alam
- Department of Architecture and Civil EngineeringDivision of Water Environment TechnologyChalmers University of TechnologyGothenburgSweden
| | - Frank Persson
- Department of Architecture and Civil EngineeringDivision of Water Environment TechnologyChalmers University of TechnologyGothenburgSweden
| | - Britt‐Marie Wilén
- Department of Architecture and Civil EngineeringDivision of Water Environment TechnologyChalmers University of TechnologyGothenburgSweden
| | - Malte Hermansson
- Chemistry and Molecular BiologyUniversity of GothenburgGothenburgSweden
| | - Oskar Modin
- Department of Architecture and Civil EngineeringDivision of Water Environment TechnologyChalmers University of TechnologyGothenburgSweden
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Liébana R, Modin O, Persson F, Szabó E, Hermansson M, Wilén BM. Combined Deterministic and Stochastic Processes Control Microbial Succession in Replicate Granular Biofilm Reactors. Environ Sci Technol 2019; 53:4912-4921. [PMID: 30969774 DOI: 10.1021/acs.est.8b06669] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Granular sludge is an efficient and compact biofilm process for wastewater treatment. However, the ecological factors involved in microbial community assembly during the granular biofilm formation are poorly understood, and little is known about the reproducibility of the process. Here, three replicate bioreactors were used to investigate microbial succession during the formation of granular biofilms. We identified three successional phases. During the initial phase, the successional turnover was high and α-diversity decreased as a result of the selection of taxa adapted to grow on acetate and form aggregates. Despite these dynamic changes, the microbial communities in the replicate reactors were similar. The second successional phase occurred when the settling time was rapidly decreased to selectively retain granules in the reactors. The influence of stochasticity on succession increased and new niches were created as granules emerged, resulting in temporarily increased α-diversity. The third successional phase occurred when the settling time was kept stable and granules dominated the biomass. Turnover was low, and selection resulted in the same abundant taxa in the reactors, but drift, which mostly affected low-abundant community members, caused the community in one reactor to diverge from the other two. Even so, performance was stable and similar between reactors.
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Affiliation(s)
- Raquel Liébana
- Division of Water Environment Technology, Department of Architecture and Civil Engineering , Chalmers University of Technology , SE-412 96 Gothenburg , Sweden
| | - Oskar Modin
- Division of Water Environment Technology, Department of Architecture and Civil Engineering , Chalmers University of Technology , SE-412 96 Gothenburg , Sweden
| | - Frank Persson
- Division of Water Environment Technology, Department of Architecture and Civil Engineering , Chalmers University of Technology , SE-412 96 Gothenburg , Sweden
| | - Enikö Szabó
- Division of Water Environment Technology, Department of Architecture and Civil Engineering , Chalmers University of Technology , SE-412 96 Gothenburg , Sweden
| | - Malte Hermansson
- Department of Chemistry and Molecular Biology , University of Gothenburg , SE405 30 Gothenburg , Sweden
| | - Britt-Marie Wilén
- Division of Water Environment Technology, Department of Architecture and Civil Engineering , Chalmers University of Technology , SE-412 96 Gothenburg , Sweden
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Fredriksson NJ, Hermansson M, Wilén BM. Long-term dynamics of the bacterial community in a Swedish full-scale wastewater treatment plant. Environ Technol 2019; 40:912-928. [PMID: 29187074 DOI: 10.1080/09593330.2017.1411396] [Citation(s) in RCA: 3] [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: 07/03/2017] [Accepted: 09/07/2017] [Indexed: 06/07/2023]
Abstract
The operational efficiency of activated sludge wastewater treatment plants depends to a large extent on the microbial community structure of the activated sludge. The aims of this paper are to describe the composition of the bacterial community in a Swedish full-scale activated sludge wastewater treatment plant, to describe the dynamics of the community and to elucidate possible causes for bacterial community composition changes. The bacterial community composition in the activated sludge was described using 16S rRNA gene libraries and monitored for 15 months by a terminal restriction fragment (T-RF) length polymorphism (T-RFLP) analysis of the 16S rRNA gene. Despite variable environmental conditions, a large fraction of the observed T-RFs were present at all times, making up at least 50% in all samples, possibly representing a relatively stable core fraction of the bacterial community. However, the proportions of the different T-RFs in this fraction as well as the T-RFs in the more variable fraction showed a significant variation over time and temperature. The difference in community composition between summer and winter coincided with observed differences in floc structure. These observations suggest a relationship between floc properties and bacterial community composition, although additional experiments are required to determine causality.
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Affiliation(s)
- Nils Johan Fredriksson
- a Department of Architecture and Civil Engineering, Water Environment Technology , Chalmers University of Technology , Gothenburg , Sweden
| | - Malte Hermansson
- b Department of Chemistry and Molecular Biology, Microbiology , University of Gothenburg , Gothenburg , Sweden
| | - Britt-Marie Wilén
- a Department of Architecture and Civil Engineering, Water Environment Technology , Chalmers University of Technology , Gothenburg , Sweden
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Wilén BM, Liébana R, Persson F, Modin O, Hermansson M. The mechanisms of granulation of activated sludge in wastewater treatment, its optimization, and impact on effluent quality. Appl Microbiol Biotechnol 2018; 102:5005-5020. [PMID: 29705957 PMCID: PMC5960003 DOI: 10.1007/s00253-018-8990-9] [Citation(s) in RCA: 73] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Revised: 04/04/2018] [Accepted: 04/05/2018] [Indexed: 12/14/2022]
Abstract
Granular activated sludge has gained increasing interest due to its potential in treating wastewater in a compact and efficient way. It is well-established that activated sludge can form granules under certain environmental conditions such as batch-wise operation with feast-famine feeding, high hydrodynamic shear forces, and short settling time which select for dense microbial aggregates. Aerobic granules with stable structure and functionality have been obtained with a range of different wastewaters seeded with different sources of sludge at different operational conditions, but the microbial communities developed differed substantially. In spite of this, granule instability occurs. In this review, the available literature on the mechanisms involved in granulation and how it affects the effluent quality is assessed with special attention given to the microbial interactions involved. To be able to optimize the process further, more knowledge is needed regarding the influence of microbial communities and their metabolism on granule stability and functionality. Studies performed at conditions similar to full-scale such as fluctuation in organic loading rate, hydrodynamic conditions, temperature, incoming particles, and feed water microorganisms need further investigations.
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Affiliation(s)
- Britt-Marie Wilén
- Division of Water Environment Technology, Department of Architecture and Civil and Engineering, Chalmers University of Technology, SE-412 96, Gothenburg, Sweden.
| | - Raquel Liébana
- Division of Water Environment Technology, Department of Architecture and Civil and Engineering, Chalmers University of Technology, SE-412 96, Gothenburg, Sweden
| | - Frank Persson
- Division of Water Environment Technology, Department of Architecture and Civil and Engineering, Chalmers University of Technology, SE-412 96, Gothenburg, Sweden
| | - Oskar Modin
- Division of Water Environment Technology, Department of Architecture and Civil and Engineering, Chalmers University of Technology, SE-412 96, Gothenburg, Sweden
| | - Malte Hermansson
- Department of Chemistry and Molecular Biology, University of Gothenburg, SE-405 30, Gothenburg, Sweden
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Szabó E, Liébana R, Hermansson M, Modin O, Persson F, Wilén BM. Comparison of the bacterial community composition in the granular and the suspended phase of sequencing batch reactors. AMB Express 2017; 7:168. [PMID: 28871435 PMCID: PMC5583138 DOI: 10.1186/s13568-017-0471-5] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [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: 05/30/2017] [Accepted: 08/30/2017] [Indexed: 11/10/2022] Open
Abstract
Granulation of activated sludge is an increasingly important area within the field of wastewater treatment. Granulation is usually achieved by high hydraulic selection pressure, which results in the wash-out of slow settling particles. The effect of the harsh wash-out conditions on the granular sludge ecosystem is not yet fully understood, but different bacterial groups may be affected to varying degrees. In this study, we used high-throughput amplicon sequencing to follow the community composition in granular sludge reactors for 12 weeks, both in the granular phase and the suspended phase (effluent). The microbiome of the washed out biomass was similar but not identical to the microbiome of the granular biomass. Certain taxa (e.g. Flavobacterium spp. and Bdellovibrio spp.) had significantly (p < 0.05) higher relative abundance in the granules compared to the effluent. Fluorescence in situ hybridization images indicated that these taxa were mainly located in the interior of granules and therefore protected from erosion. Other taxa (e.g. Meganema sp. and Zooglea sp.) had significantly lower relative abundance in the granules compared to the effluent, and appeared to be mainly located on the surface of granules and therefore subject to erosion. Despite being washed out, these taxa were among the most abundant members of the granular sludge communities and were likely growing fast in the reactors. The ratio between relative abundance in the granular biomass and in the effluent did not predict temporal variation of the taxa in the reactors, but it did appear to predict the spatial location of the taxa in the granules.
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Szabó E, Liébana R, Hermansson M, Modin O, Persson F, Wilén BM. Microbial Population Dynamics and Ecosystem Functions of Anoxic/Aerobic Granular Sludge in Sequencing Batch Reactors Operated at Different Organic Loading Rates. Front Microbiol 2017; 8:770. [PMID: 28507540 PMCID: PMC5410608 DOI: 10.3389/fmicb.2017.00770] [Citation(s) in RCA: 87] [Impact Index Per Article: 12.4] [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: 08/18/2016] [Accepted: 04/13/2017] [Indexed: 11/13/2022] Open
Abstract
The granular sludge process is an effective, low-footprint alternative to conventional activated sludge wastewater treatment. The architecture of the microbial granules allows the co-existence of different functional groups, e.g., nitrifying and denitrifying communities, which permits compact reactor design. However, little is known about the factors influencing community assembly in granular sludge, such as the effects of reactor operation strategies and influent wastewater composition. Here, we analyze the development of the microbiomes in parallel laboratory-scale anoxic/aerobic granular sludge reactors operated at low (0.9 kg m-3d-1), moderate (1.9 kg m-3d-1) and high (3.7 kg m-3d-1) organic loading rates (OLRs) and the same ammonium loading rate (0.2 kg NH4-N m-3d-1) for 84 days. Complete removal of organic carbon and ammonium was achieved in all three reactors after start-up, while the nitrogen removal (denitrification) efficiency increased with the OLR: 0% at low, 38% at moderate, and 66% at high loading rate. The bacterial communities at different loading rates diverged rapidly after start-up and showed less than 50% similarity after 6 days, and below 40% similarity after 84 days. The three reactor microbiomes were dominated by different genera (mainly Meganema, Thauera, Paracoccus, and Zoogloea), but these genera have similar ecosystem functions of EPS production, denitrification and polyhydroxyalkanoate (PHA) storage. Many less abundant but persistent taxa were also detected within these functional groups. The bacterial communities were functionally redundant irrespective of the loading rate applied. At steady-state reactor operation, the identity of the core community members was rather stable, but their relative abundances changed considerably over time. Furthermore, nitrifying bacteria were low in relative abundance and diversity in all reactors, despite their large contribution to nitrogen turnover. The results suggest that the OLR has considerable impact on the composition of the granular sludge communities, but also that the granule communities can be dynamic even at steady-state reactor operation due to high functional redundancy of several key guilds. Knowledge about microbial diversity with specific functional guilds under different operating conditions can be important for engineers to predict the stability of reactor functions during the start-up and continued reactor operation.
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Affiliation(s)
- Enikö Szabó
- Division of Water Environment Technology, Department of Civil and Environmental Engineering, Chalmers University of TechnologyGothenburg, Sweden
| | - Raquel Liébana
- Division of Water Environment Technology, Department of Civil and Environmental Engineering, Chalmers University of TechnologyGothenburg, Sweden
| | - Malte Hermansson
- Department of Chemistry and Molecular Biology, University of GothenburgGothenburg, Sweden
| | - Oskar Modin
- Division of Water Environment Technology, Department of Civil and Environmental Engineering, Chalmers University of TechnologyGothenburg, Sweden
| | - Frank Persson
- Division of Water Environment Technology, Department of Civil and Environmental Engineering, Chalmers University of TechnologyGothenburg, Sweden
| | - Britt-Marie Wilén
- Division of Water Environment Technology, Department of Civil and Environmental Engineering, Chalmers University of TechnologyGothenburg, Sweden
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Persson F, Suarez C, Hermansson M, Plaza E, Sultana R, Wilén BM. Community structure of partial nitritation-anammox biofilms at decreasing substrate concentrations and low temperature. Microb Biotechnol 2016; 10:761-772. [PMID: 27863060 PMCID: PMC5481546 DOI: 10.1111/1751-7915.12435] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [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: 06/15/2015] [Revised: 09/15/2016] [Accepted: 09/28/2016] [Indexed: 11/28/2022] Open
Abstract
Partial nitritation-anammox (PNA) permits energy effective nitrogen removal. Today PNA is used for treatment of concentrated and warm side streams at wastewater treatment plants, but not the more diluted and colder main stream. To implement PNA in the main stream, better knowledge about microbial communities at the typical environmental conditions is necessary. In order to investigate the response of PNA microbial communities to decreasing substrate availability, we have operated a moving bed biofilm reactor (MBBR) at decreasing reactor concentrations (311-27 mg-N l-1 of ammonium) and low temperature (13°C) for 302 days and investigated the biofilm community using high throughput amplicon sequencing; quantitative PCR; and fluorescence in situ hybridization. The anammox bacteria (Ca. Brocadia) constituted a large fraction of the biomass with fewer aerobic ammonia oxidizing bacteria (AOB) and even less nitrite oxidizing bacteria (NOB; Nitrotoga, Nitrospira and Nitrobacter). Still, NOB had considerable impact on the process performance. The anammox bacteria, AOB and NOB all harboured more than one population, indicating some diversity, and the heterotrophic bacterial community was diverse (seven phyla). Despite the downshifts in substrate availability, changes in the relative abundance and composition of anammox bacteria, AOB and NOB were small and also the heterotrophic community showed little changes in composition. This indicates stability of PNA MBBR communities towards decreasing substrate availability and suggests that even heterotrophic bacteria are integral components of these communities.
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Affiliation(s)
- Frank Persson
- Division of Water Environment Technology, Department of Civil and Environmental Engineering, Chalmers University of Technology, SE-41296, Gothenburg, Sweden
| | - Carolina Suarez
- Department of Chemistry and Molecular Biology, University of Gothenburg, SE-40530, Gothenburg, Sweden
| | - Malte Hermansson
- Department of Chemistry and Molecular Biology, University of Gothenburg, SE-40530, Gothenburg, Sweden
| | - Elzbieta Plaza
- Department of Sustainable Development, Environmental Science and Engineering (SEED), Royal Institute of Technology (KTH), Teknikringen 76, SE-100 44, Stockholm, Sweden
| | - Razia Sultana
- Department of Sustainable Development, Environmental Science and Engineering (SEED), Royal Institute of Technology (KTH), Teknikringen 76, SE-100 44, Stockholm, Sweden
| | - Britt-Marie Wilén
- Division of Water Environment Technology, Department of Civil and Environmental Engineering, Chalmers University of Technology, SE-41296, Gothenburg, Sweden
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Piculell M, Suarez C, Li C, Christensson M, Persson F, Wagner M, Hermansson M, Jönsson K, Welander T. The inhibitory effects of reject water on nitrifying populations grown at different biofilm thickness. Water Res 2016; 104:292-302. [PMID: 27551781 DOI: 10.1016/j.watres.2016.08.027] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [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: 04/27/2016] [Revised: 08/12/2016] [Accepted: 08/13/2016] [Indexed: 06/06/2023]
Abstract
Suppression of nitrite oxidizing bacteria (NOB) is of vital importance to achieve successful, energy efficient, mainstream anammox processes for wastewater treatment. In this study, biofilm carriers from a fully nitrifying MBBR system, fed with mainstream wastewater, were temporarily exposed to reject water from sludge dewatering, to evaluate this as a possible strategy to inhibit NOB and achieve nitrite production under realistic conditions. Two different carrier types were compared, in which biofilm thickness was maintained at approximately 400 and 50 μm, respectively, and reject treatment was tested at different exposure time and loading rates. Reject exposure almost always resulted in an increased nitrite production in the thinner biofilm, and overall, nitrifiers growing in the thin biofilm were more sensitive than those grown in the thicker biofilm. The effect from reject exposure remained in the systems for four days after returning to mainstream operation, with nitrite production gradually increasing for three days. Increased concentrations of free ammonia correlated with reject exposure and may be the cause of inhibition, although other factors cannot be excluded.
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Affiliation(s)
- Maria Piculell
- Veolia Water Technologies AB - AnoxKaldnes, Klosterängsvägen 11A, SE-226 47 Lund, Sweden.
| | - Carolina Suarez
- Dept. of Chemistry and Molecular Biology/Microbiology, University of Gothenburg, Medicinaregatan 9E, SE-413 90 Gothenburg, Sweden
| | - Chunyan Li
- Water Chemistry and Water Technology, Engler-Bunte-Institut, Karlsruhe Institute of Technology, Engler-Bunte-Ring 9, 76131 Karlsruhe, Germany
| | - Magnus Christensson
- Veolia Water Technologies AB - AnoxKaldnes, Klosterängsvägen 11A, SE-226 47 Lund, Sweden
| | - Frank Persson
- Water Environment Technology, Dept. of Civil and Environmental Engineering, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden
| | - Michael Wagner
- Water Chemistry and Water Technology, Engler-Bunte-Institut, Karlsruhe Institute of Technology, Engler-Bunte-Ring 9, 76131 Karlsruhe, Germany
| | - Malte Hermansson
- Dept. of Chemistry and Molecular Biology/Microbiology, University of Gothenburg, Medicinaregatan 9E, SE-413 90 Gothenburg, Sweden
| | - Karin Jönsson
- Water and Environmental Engineering, Dept. of Chemical Engineering, Lund University, P.O. Box 124, SE-221 00 Lund, Sweden
| | - Thomas Welander
- Veolia Water Technologies AB - AnoxKaldnes, Klosterängsvägen 11A, SE-226 47 Lund, Sweden
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Abstract
The activated sludge process is commonly used to treat wastewater by aerobic oxidation of organic pollutants into carbon dioxide and water. However, several nonoxidative mechanisms can also contribute to removal of organics. Sorption onto activated sludge can remove a large fraction of the colloidal and particulate wastewater organics. Intracellular storage of, e.g., polyhydroxyalkanoates (PHA), triacylglycerides (TAG), or wax esters can convert wastewater organics into precursors for high-value products. Recently, several environmental, economic, and technological drivers have stimulated research on nonoxidative removal of organics for wastewater treatment. In this paper, we review these nonoxidative removal mechanisms as well as the existing and emerging process configurations that make use of them for wastewater treatment. Better utilization of nonoxidative processes in activated sludge could reduce the wasteful aerobic oxidation of organic compounds and lead to more resource-efficient wastewater treatment plants.
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Affiliation(s)
- Oskar Modin
- Division of Water Environment Technology, Department of Civil and Environmental Engineering, Chalmers University of Technology, Gothenburg, Sweden
| | - Frank Persson
- Division of Water Environment Technology, Department of Civil and Environmental Engineering, Chalmers University of Technology, Gothenburg, Sweden
| | - Britt-Marie Wilén
- Division of Water Environment Technology, Department of Civil and Environmental Engineering, Chalmers University of Technology, Gothenburg, Sweden
| | - Malte Hermansson
- Department of Chemistry and Molecular Biology, Gothenburg University, Gothenburg, Sweden
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Saheb Alam S, Persson F, Wilén BM, Hermansson M, Modin O. Effects of storage on mixed-culture biological electrodes. Sci Rep 2015; 5:18433. [PMID: 26678949 PMCID: PMC4683449 DOI: 10.1038/srep18433] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [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: 09/24/2015] [Accepted: 11/18/2015] [Indexed: 01/24/2023] Open
Abstract
Storage methods are important to preserve the viability and biochemical characteristics of microbial cultures between experiments or during periods when bioreactors are inactive. Most of the research on storage has focused on isolates; however, there is an increasing interest in methods for mixed cultures, which are of relevance in environmental biotechnology. The purpose of this study was to investigate the effect of different storage methods on electrochemically active enrichment cultures. Acetate-oxidizing bioanodes generating a current density of about 5 A m−2 were enriched in a microbial electrolysis cell. The effect of five weeks of storage was evaluated using electrochemical techniques and microbial community analysis. Storage by refrigeration resulted in quicker re-activation than freezing in 10% glycerol, while the bioelectrochemical activity was entirely lost after storage using dehydration. The results showed that the bioelectrochemical activity of bioanodes stored at low temperature could be retained. However, during the re-activation period the bioanodes only recovered 75% of the current density generated before storage and the bacterial communities were different in composition and more diverse after storage than before.
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Affiliation(s)
- Soroush Saheb Alam
- Division of Water Environment Technology, Department of Civil and Environmental Engineering, Chalmers University of Technology, Gothenburg, Sweden
| | - Frank Persson
- Division of Water Environment Technology, Department of Civil and Environmental Engineering, Chalmers University of Technology, Gothenburg, Sweden
| | - Britt-Marie Wilén
- Division of Water Environment Technology, Department of Civil and Environmental Engineering, Chalmers University of Technology, Gothenburg, Sweden
| | - Malte Hermansson
- Chemistry and Molecular Biology, University of Gothenburg, Gothenburg, Sweden
| | - Oskar Modin
- Division of Water Environment Technology, Department of Civil and Environmental Engineering, Chalmers University of Technology, Gothenburg, Sweden
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Suarez C, Persson F, Hermansson M. Predation of nitritation–anammox biofilms used for nitrogen removal from wastewater. FEMS Microbiol Ecol 2015; 91:fiv124. [DOI: 10.1093/femsec/fiv124] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/08/2015] [Indexed: 11/12/2022] Open
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Åström J, Pettersson TJR, Reischer GH, Norberg T, Hermansson M. Incorporating expert judgments in utility evaluation of bacteroidales qPCR assays for microbial source tracking in a drinking water source. Environ Sci Technol 2015; 49:1311-8. [PMID: 25545113 PMCID: PMC5509012 DOI: 10.1021/es504579j] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Several assays for the detection of host-specific genetic markers of the order Bacteroidales have been developed and used for microbial source tracking (MST) in environmental waters. It is recognized that the source-sensitivity and source-specificity are unknown and variable when introducing these assays in new geographic regions, which reduces their reliability and use. A Bayesian approach was developed to incorporate expert judgments with regional assay sensitivity and specificity assessments in a utility evaluation of a human and a ruminant-specific qPCR assay for MST in a drinking water source. Water samples from Lake Rådasjön were analyzed for E. coli, intestinal enterococci and somatic coliphages through cultivation and for human (BacH) and ruminant-specific (BacR) markers through qPCR assays. Expert judgments were collected regarding the probability of human and ruminant fecal contamination based on fecal indicator organism data and subjective information. Using Bayes formula, the conditional probability of a true human or ruminant fecal contamination given the presence of BacH or BacR was determined stochastically from expert judgments and regional qPCR assay performance, using Beta distributions to represent uncertainties. A web-based computational tool was developed for the procedure, which provides a measure of confidence to findings of host-specific markers and demonstrates the information value from these assays.
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Affiliation(s)
- Johan Åström
- Tyréns AB, Lilla Badhusgatan 2, SE-411 21 Gothenburg, Sweden
| | - Thomas J. R. Pettersson
- Water Environment Technology, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden
| | - Georg H. Reischer
- Interuniversity Center Water & Health, Institute of Chemical Engineering, Vienna University of Technology, Gumpendorfer Straße 1a/166-5-2, A-1060 Vienna, Austria
| | - Tommy Norberg
- Department of Mathematical Sciences, University of Gothenburg and Chalmers University of Technology, SE-412 96 Gothenburg, Sweden
| | - Malte Hermansson
- Department of Chemistry and Molecular Biology, Microbiology, University of Gothenburg, SE-405 30 Gothenburg, Sweden
- Corresponding Author Phone +46(0)31 786 2575; fax +46(0)31 786 2599; .
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Abstract
BACKGROUND Terminal restriction fragment length polymorphism (T-RFLP) analysis is a DNA-fingerprinting method that can be used for comparisons of the microbial community composition in a large number of samples. There is no consensus on how T-RFLP data should be treated and analyzed before comparisons between samples are made, and several different approaches have been proposed in the literature. The analysis of T-RFLP data can be cumbersome and time-consuming, and for large datasets manual data analysis is not feasible. The currently available tools for automated T-RFLP analysis, although valuable, offer little flexibility, and few, if any, options regarding what methods to use. To enable comparisons and combinations of different data treatment methods an analysis template and an extensive collection of macros for T-RFLP data analysis using Microsoft Excel were developed. RESULTS The Tools for T-RFLP data analysis template provides procedures for the analysis of large T-RFLP datasets including application of a noise baseline threshold and setting of the analysis range, normalization and alignment of replicate profiles, generation of consensus profiles, normalization and alignment of consensus profiles and final analysis of the samples including calculation of association coefficients and diversity index. The procedures are designed so that in all analysis steps, from the initial preparation of the data to the final comparison of the samples, there are various different options available. The parameters regarding analysis range, noise baseline, T-RF alignment and generation of consensus profiles are all given by the user and several different methods are available for normalization of the T-RF profiles. In each step, the user can also choose to base the calculations on either peak height data or peak area data. CONCLUSIONS The Tools for T-RFLP data analysis template enables an objective and flexible analysis of large T-RFLP datasets in a widely used spreadsheet application.
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Affiliation(s)
- Nils Johan Fredriksson
- Department of Medical Biochemistry and Cell Biology, Institute of Biomedicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
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Fredriksson NJ, Hermansson M, Wilén BM. Impact of T-RFLP data analysis choices on assessments of microbial community structure and dynamics. BMC Bioinformatics 2014; 15:360. [PMID: 25381552 PMCID: PMC4232699 DOI: 10.1186/s12859-014-0360-8] [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] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2013] [Accepted: 10/23/2014] [Indexed: 12/25/2022] Open
Abstract
Background Terminal restriction fragment length polymorphism (T-RFLP) analysis is a common DNA-fingerprinting technique used for comparisons of complex microbial communities. Although the technique is well established there is no consensus on how to treat T-RFLP data to achieve the highest possible accuracy and reproducibility. This study focused on two critical steps in the T-RFLP data treatment: the alignment of the terminal restriction fragments (T-RFs), which enables comparisons of samples, and the normalization of T-RF profiles, which adjusts for differences in signal strength, total fluorescence, between samples. Results Variations in the estimation of T-RF sizes were observed and these variations were found to affect the alignment of the T-RFs. A novel method was developed which improved the alignment by adjusting for systematic shifts in the T-RF size estimations between the T-RF profiles. Differences in total fluorescence were shown to be caused by differences in sample concentration and by the gel loading. Five normalization methods were evaluated and the total fluorescence normalization procedure based on peak height data was found to increase the similarity between replicate profiles the most. A high peak detection threshold, alignment correction, normalization and the use of consensus profiles instead of single profiles increased the similarity of replicate T-RF profiles, i.e. lead to an increased reproducibility. The impact of different treatment methods on the outcome of subsequent analyses of T-RFLP data was evaluated using a dataset from a longitudinal study of the bacterial community in an activated sludge wastewater treatment plant. Whether the alignment was corrected or not and if and how the T-RF profiles were normalized had a substantial impact on ordination analyses, assessments of bacterial dynamics and analyses of correlations with environmental parameters. Conclusions A novel method for the evaluation and correction of the alignment of T-RF profiles was shown to reduce the uncertainty and ambiguity in alignments of T-RF profiles. Large differences in the outcome of assessments of bacterial community structure and dynamics were observed between different alignment and normalization methods. The results of this study can therefore be of value when considering what methods to use in the analysis of T-RFLP data. Electronic supplementary material The online version of this article (doi:10.1186/s12859-014-0360-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Nils Johan Fredriksson
- Department of Medical Biochemistry and Cell Biology, Institute of Biomedicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
| | - Malte Hermansson
- Department of Chemistry and Molecular Biology, University of Gothenburg, Gothenburg, Sweden.
| | - Britt-Marie Wilén
- Department of Civil and Environmental Engineering, Water Environment Technology, Chalmers University of Technology, Gothenburg, Sweden.
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Norberg P, Bergström M, Hermansson M. Complete nucleotide sequence and analysis of two conjugative broad host range plasmids from a marine microbial biofilm. PLoS One 2014; 9:e92321. [PMID: 24647540 PMCID: PMC3960245 DOI: 10.1371/journal.pone.0092321] [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] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2013] [Accepted: 02/20/2014] [Indexed: 11/26/2022] Open
Abstract
The complete nucleotide sequence of plasmids pMCBF1 and pMCBF6 was determined and analyzed. pMCBF1 and pMCBF6 form a novel clade within the IncP-1 plasmid family designated IncP-1 ς. The plasmids were exogenously isolated earlier from a marine biofilm. pMCBF1 (62 689 base pairs; bp) and pMCBF6 (66 729 bp) have identical backbones, but differ in their mercury resistance transposons. pMCBF1 carries Tn5053 and pMCBF6 carries Tn5058. Both are flanked by 5 bp direct repeats, typical of replicative transposition. Both insertions are in the vicinity of a resolvase gene in the backbone, supporting the idea that both transposons are “res-site hunters” that preferably insert close to and use external resolvase functions. The similarity of the backbones indicates recent insertion of the two transposons and the ongoing dynamics of plasmid evolution in marine biofilms. Both plasmids also carry the insertion sequence ISPst1, albeit without flanking repeats. ISPs1is located in an unusual site within the control region of the plasmid. In contrast to most known IncP-1 plasmids the pMCBF1/pMCBF6 backbone has no insert between the replication initiation gene (trfA) and the vegetative replication origin (oriV). One pMCBF1/pMCBF6 block of about 2.5 kilo bases (kb) has no similarity with known sequences in the databases. Furthermore, insertion of three genes with similarity to the multidrug efflux pump operon mexEF and a gene from the NodT family of the tripartite multi-drug resistance-nodulation-division (RND) system in Pseudomonas aeruginosa was found. They do not seem to confer antibiotic resistance to the hosts of pMCBF1/pMCBF6, but the presence of RND on promiscuous plasmids may have serious implications for the spread of antibiotic multi-resistance.
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Affiliation(s)
- Peter Norberg
- Department of Infectious Diseases, University of Gothenburg, Göteborg, Sweden
| | - Maria Bergström
- Department of Chemistry and Molecular Biology, Microbiology, University of Gothenburg, Göteborg, Sweden
| | - Malte Hermansson
- Department of Chemistry and Molecular Biology, Microbiology, University of Gothenburg, Göteborg, Sweden
- * E-mail:
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Persson F, Sultana R, Suarez C, Hermansson M, Plaza E, Wilén BM. Structure and composition of biofilm communities in a moving bed biofilm reactor for nitritation-anammox at low temperatures. Bioresour Technol 2014; 154:267-273. [PMID: 24412479 DOI: 10.1016/j.biortech.2013.12.062] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [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: 10/09/2013] [Revised: 12/10/2013] [Accepted: 12/14/2013] [Indexed: 06/03/2023]
Abstract
It is a challenge to apply anaerobic ammonium oxidation (anammox) for nitrogen removal from wastewater at low temperatures. Maintenance of anammox- and aerobic ammonia oxidizing bacteria (AOB) and suppression of nitrite oxidizing bacteria (NOB) are key issues. In this work, a nitritation-anammox moving bed biofilm pilot reactor was operated at 19-10°C for 300 d. Nitrogen removal was decreasing, but stable, at 19-13°C. At 10°C removal became unstable. Quantitative PCR, fluorescence in situ hybridization and gene sequencing showed that no major microbial community changes were observed with decreased temperature. Anammox bacteria dominated the biofilm (0.9-1.2 × 10(14) 16S rRNA copies m(-2)). Most anammox bacteria were similar to Brocadia sp. 40, but another smaller Brocadia population was present near the biofilm-water interface, where also the AOB community (Nitrosomonas) was concentrated in thin layers (1.8-5.3 × 10(12) amoA copies m(-2)). NOB (Nitrobacter, Nitrospira) were always present at low concentrations (<1.3 × 10(11) 16S rRNA copies m(-2)).
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Affiliation(s)
- Frank Persson
- Water Environment Technology, Dept. of Civil and Environmental Engineering, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden.
| | - Razia Sultana
- Dept. of Land and Water Resources Engineering, Royal Institute of Technology (KTH), Teknikringen 76, SE-100 44 Stockholm, Sweden
| | - Carolina Suarez
- Dept. of Chemistry and Molecular Biology/Microbiology, University of Gothenburg, Medicinaregatan 9E, SE-413 90 Gothenburg, Sweden
| | - Malte Hermansson
- Dept. of Chemistry and Molecular Biology/Microbiology, University of Gothenburg, Medicinaregatan 9E, SE-413 90 Gothenburg, Sweden
| | - Elzbieta Plaza
- Dept. of Land and Water Resources Engineering, Royal Institute of Technology (KTH), Teknikringen 76, SE-100 44 Stockholm, Sweden
| | - Britt-Marie Wilén
- Water Environment Technology, Dept. of Civil and Environmental Engineering, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden
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27
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Almstrand R, Persson F, Daims H, Ekenberg M, Christensson M, Wilén BM, Sörensson F, Hermansson M. Three-dimensional stratification of bacterial biofilm populations in a moving bed biofilm reactor for nitritation-anammox. Int J Mol Sci 2014; 15:2191-206. [PMID: 24481066 PMCID: PMC3958845 DOI: 10.3390/ijms15022191] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [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: 12/23/2013] [Revised: 01/10/2014] [Accepted: 01/14/2014] [Indexed: 11/18/2022] Open
Abstract
Moving bed biofilm reactors (MBBRs) are increasingly used for nitrogen removal with nitritation-anaerobic ammonium oxidation (anammox) processes in wastewater treatment. Carriers provide protected surfaces where ammonia oxidizing bacteria (AOB) and anammox bacteria form complex biofilms. However, the knowledge about the organization of microbial communities in MBBR biofilms is sparse. We used new cryosectioning and imaging methods for fluorescence in situ hybridization (FISH) to study the structure of biofilms retrieved from carriers in a nitritation-anammox MBBR. The dimensions of the carrier compartments and the biofilm cryosections after FISH showed good correlation, indicating little disturbance of biofilm samples by the treatment. FISH showed that Nitrosomonas europaea/eutropha-related cells dominated the AOB and Candidatus Brocadia fulgida-related cells dominated the anammox guild. New carriers were initially colonized by AOB, followed by anammox bacteria proliferating in the deeper biofilm layers, probably in anaerobic microhabitats created by AOB activity. Mature biofilms showed a pronounced three-dimensional stratification where AOB dominated closer to the biofilm-water interface, whereas anammox were dominant deeper into the carrier space and towards the walls. Our results suggest that current mathematical models may be oversimplifying these three-dimensional systems and unless the multidimensionality of these systems is considered, models may result in suboptimal design of MBBR carriers.
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Affiliation(s)
- Robert Almstrand
- Department of Chemistry & Molecular Biology, Microbiology, University of Gothenburg, Box 462, Göteborg SE-405 30, Sweden.
| | - Frank Persson
- Water Environment Technology, Department of Civil and Environmental Engineering, Chalmers University of Technology, Göteborg SE-412 96, Sweden.
| | - Holger Daims
- Division of Microbial Ecology, Department of Microbiology and Ecosystem Science, University of Vienna, Vienna 1090, Austria.
| | - Maria Ekenberg
- AnoxKaldnes AB, Klosterängsvägen 11A, Lund SE-226 47, Sweden.
| | | | - Britt-Marie Wilén
- Water Environment Technology, Department of Civil and Environmental Engineering, Chalmers University of Technology, Göteborg SE-412 96, Sweden.
| | - Fred Sörensson
- Department of Chemistry & Molecular Biology, Microbiology, University of Gothenburg, Box 462, Göteborg SE-405 30, Sweden.
| | - Malte Hermansson
- Department of Chemistry & Molecular Biology, Microbiology, University of Gothenburg, Box 462, Göteborg SE-405 30, Sweden.
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Fredriksson NJ, Hermansson M, Wilén BM. The choice of PCR primers has great impact on assessments of bacterial community diversity and dynamics in a wastewater treatment plant. PLoS One 2013; 8:e76431. [PMID: 24098498 PMCID: PMC3788133 DOI: 10.1371/journal.pone.0076431] [Citation(s) in RCA: 70] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2013] [Accepted: 08/27/2013] [Indexed: 02/01/2023] Open
Abstract
Assessments of bacterial community diversity and dynamics are fundamental for the understanding of microbial ecology as well as biotechnological applications. We show that the choice of PCR primers has great impact on the results of analyses of diversity and dynamics using gene libraries and DNA fingerprinting. Two universal primer pairs targeting the 16S rRNA gene, 27F&1492R and 63F&M1387R, were compared and evaluated by analyzing the bacterial community in the activated sludge of a large-scale wastewater treatment plant. The two primer pairs targeted distinct parts of the bacterial community, none encompassing the other, both with similar richness. Had only one primer pair been used, very different conclusions had been drawn regarding dominant phylogenetic and putative functional groups. With 27F&1492R, Betaproteobacteria would have been determined to be the dominating taxa while 63F&M1387R would have described Alphaproteobacteria as the most common taxa. Microscopy and fluorescence in situ hybridization analysis showed that both Alphaproteobacteria and Betaproteobacteria were abundant in the activated sludge, confirming that the two primer pairs target two different fractions of the bacterial community. Furthermore, terminal restriction fragment polymorphism analyses of a series of four activated sludge samples showed that the two primer pairs would have resulted in different conclusions about community stability and the factors contributing to changes in community composition. In conclusion, different PCR primer pairs, although considered universal, target different ranges of bacteria and will thus show the diversity and dynamics of different fractions of the bacterial community in the analyzed sample. We also show that while a database search can serve as an indicator of how universal a primer pair is, an experimental assessment is necessary to evaluate the suitability for a specific environmental sample.
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Affiliation(s)
- Nils Johan Fredriksson
- Department of Civil and Environmental Engineering, Water Environment Technology, Chalmers University of Technology, Gothenburg, Sweden
- * E-mail:
| | - Malte Hermansson
- Department of Chemistry and Molecular Biology, University of Gothenburg, Gothenburg, Sweden
| | - Britt-Marie Wilén
- Department of Civil and Environmental Engineering, Water Environment Technology, Chalmers University of Technology, Gothenburg, Sweden
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Aström J, Pettersson TJR, Reischer GH, Hermansson M. Short-term microbial release during rain events from on-site sewers and cattle in a surface water source. J Water Health 2013; 11:430-442. [PMID: 23981872 DOI: 10.2166/wh.2013.226] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The protection of drinking water from pathogens such as Cryptosporidium and Giardia requires an understanding of the short-term microbial release from faecal contamination sources in the catchment. Flow-weighted samples were collected during two rainfall events in a stream draining an area with on-site sewers and during two rainfall events in surface runoff from a bovine cattle pasture. Samples were analysed for human (BacH) and ruminant (BacR) Bacteroidales genetic markers through quantitative polymerase chain reaction (qPCR) and for sorbitol-fermenting bifidobacteria through culturing as a complement to traditional faecal indicator bacteria, somatic coliphages and the parasitic protozoa Cryptosporidium spp. and Giardia spp. analysed by standard methods. Significant positive correlations were observed between BacH, Escherichia coli, intestinal enterococci, sulphite-reducing Clostridia, turbidity, conductivity and UV254 in the stream contaminated by on-site sewers. For the cattle pasture, no correlation was found between any of the genetic markers and the other parameters. Although parasitic protozoa were not detected, the analysis for genetic markers provided baseline data on the short-term faecal contamination due to these potential sources of parasites. Background levels of BacH and BacR makers in soil emphasise the need to including soil reference samples in qPCR-based analyses for Bacteroidales genetic markers.
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Affiliation(s)
- Johan Aström
- Tyréns AB, Lilla Badhusgatan 2, Gothenburg, Sweden.
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Sokolova E, Aström J, Pettersson TJR, Bergstedt O, Hermansson M. Estimation of pathogen concentrations in a drinking water source using hydrodynamic modelling and microbial source tracking. J Water Health 2012; 10:358-370. [PMID: 22960480 DOI: 10.2166/wh.2012.183] [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] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The faecal contamination of drinking water sources can lead to waterborne disease outbreaks. To estimate a potential risk for waterborne infections caused by faecal contamination of drinking water sources, knowledge of the pathogen concentrations in raw water is required. We suggest a novel approach to estimate pathogen concentrations in a drinking water source by using microbial source tracking data and fate and transport modelling. First, the pathogen (norovirus, Cryptosporidium, Escherichia coli O157/H7) concentrations in faecal contamination sources around the drinking water source Lake Rådasjön in Sweden were estimated for endemic and epidemic conditions using measured concentrations of faecal indicators (E. coli and Bacteroidales genetic markers). Afterwards, the fate and transport of pathogens within the lake were simulated using a three-dimensional coupled hydrodynamic and microbiological model. This approach provided information on the contribution from different contamination sources to the pathogen concentrations at the water intake of a drinking water treatment plant. This approach addresses the limitations of monitoring and provides data for quantitative microbial risk assessment (QMRA) and risk management in the context of faecal contamination of surface drinking water sources.
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Affiliation(s)
- Ekaterina Sokolova
- Water Environment Technology, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden.
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31
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Fredriksson NJ, Hermansson M, Wilén BM. Diversity and dynamics of Archaea in an activated sludge wastewater treatment plant. BMC Microbiol 2012; 12:140. [PMID: 22784022 PMCID: PMC3607932 DOI: 10.1186/1471-2180-12-140] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2012] [Accepted: 07/11/2012] [Indexed: 11/10/2022] Open
Abstract
Background The activated sludge process is one of the most widely used methods for treatment of wastewater and the microbial community composition in the sludge is important for the process operation. While the bacterial communities have been characterized in various activated sludge systems little is known about archaeal communities in activated sludge. The diversity and dynamics of the Archaea community in a full-scale activated sludge wastewater treatment plant were investigated by fluorescence in situ hybridization, terminal restriction fragment length polymorphism analysis and cloning and sequencing of 16S rRNA genes. Results The Archaea community was dominated by Methanosaeta-like species. During a 15 month period major changes in the community composition were only observed twice despite seasonal variations in environmental and operating conditions. Water temperature appeared to be the process parameter that affected the community composition the most. Several terminal restriction fragments also showed strong correlations with sludge properties and effluent water properties. The Archaea were estimated to make up 1.6% of total cell numbers in the activated sludge and were present both as single cells and colonies of varying sizes. Conclusions The results presented here show that Archaea can constitute a constant and integral part of the activated sludge and that it can therefore be useful to include Archaea in future studies of microbial communities in activated sludge.
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Kuronen M, Hermansson M, Manninen O, Zech I, Talvitie M, Laitinen T, Gröhn O, Somerharju P, Eckhardt M, Cooper JD, Lehesjoki AE, Lahtinen U, Kopra O. Galactolipid deficiency in the early pathogenesis of neuronal ceroid lipofuscinosis model Cln8mnd: implications to delayed myelination and oligodendrocyte maturation. Neuropathol Appl Neurobiol 2012; 38:471-86. [DOI: 10.1111/j.1365-2990.2011.01233.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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Harris C, Remedios D, Aptowitzer T, Keat A, Hamilton L, Guile G, Belkhiri A, Newman D, Toms A, Macgregor A, Gaffney K, Morton L, Jones GT, MacDonald AG, Downham C, Macfarlane GJ, Tillett W, Jadon D, Wallis D, Costa L, Waldron N, Griffith N, Cavill C, Korendowych E, de Vries C, McHugh N, Iaremenko O, Fedkov D, Emery P, Baeten D, Sieper J, Braun J, van der Heijde D, McInnes I, Van Laar J, Landewe R, Wordsworth BP, Wollenhaupt J, Kellner H, Paramarta I, Bertolino A, Wright AM, Hueber W, Sofat N, Smee C, Hermansson M, Wajed J, Sanyal K, Kiely P, Howard M, Howe FA, Barrick TR, Abraham AM, Pearce MS, Mann KD, Francis RM, Birrell F, Carr A, Macleod I, Ng WF, Kavanaugh A, van der Heijde D, Chattopadhyay C, Gladman D, Mease P, McInnes I, Krueger G, Xu W, Goldstein N, Beutler A, Van Laar J, Baraliakos X, Braun J, Laurent DD, Baeten D, van der Heijde D, Sieper J, Emery P, McInnes I, Landewe R, Wordsworth BP, Wollenhaupt J, Kellner H, Wright AM, Gsteiger S, Hueber W, Conaghan PG, Peterfy CG, DiCarlo J, Olech E, Alberts AR, Alper JA, Devenport J, Anisfeld AM, Troum OM, Cooper P, Gimpel M, Deakin G, Jameson K, Godtschailk M, Gadola S, Stokes M, Cooper C, Gordon C, Kalunian K, Petri M, Strand V, Kilgallen B, Barry A, Wallace D, Flurey CA, Morris M, Pollock J, Hughes R, Richards P, Hewlett S. Oral abstracts 1: Spondyloarthropathies * O1. Detecting axial spondyloarthritis amongst primary care back pain referrals. Rheumatology (Oxford) 2012. [DOI: 10.1093/rheumatology/kes118] [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: 11/13/2022] Open
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Almstrand R, Lydmark P, Lindgren PE, Sörensson F, Hermansson M. Dynamics of specific ammonia-oxidizing bacterial populations and nitrification in response to controlled shifts of ammonium concentrations in wastewater. Appl Microbiol Biotechnol 2012; 97:2183-91. [DOI: 10.1007/s00253-012-4047-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2012] [Revised: 03/16/2012] [Accepted: 03/19/2012] [Indexed: 12/01/2022]
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Sokolova E, Aström J, Pettersson TJR, Bergstedt O, Hermansson M. Decay of Bacteroidales genetic markers in relation to traditional fecal indicators for water quality modeling of drinking water sources. Environ Sci Technol 2012; 46:892-900. [PMID: 22148545 DOI: 10.1021/es2024498] [Citation(s) in RCA: 16] [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: 05/03/2023]
Abstract
The implementation of microbial fecal source tracking (MST) methods in drinking water management is limited by the lack of knowledge on the transport and decay of host-specific genetic markers in water sources. To address these limitations, the decay and transport of human (BacH) and ruminant (BacR) fecal Bacteroidales 16S rRNA genetic markers in a drinking water source (Lake Rådasjön in Sweden) were simulated using a microbiological model coupled to a three-dimensional hydrodynamic model. The microbiological model was calibrated using data from outdoor microcosm trials performed in March, August, and November 2010 to determine the decay of BacH and BacR markers in relation to traditional fecal indicators. The microcosm trials indicated that the persistence of BacH and BacR in the microcosms was not significantly different from the persistence of traditional fecal indicators. The modeling of BacH and BacR transport within the lake illustrated that the highest levels of genetic markers at the raw water intakes were associated with human fecal sources (on-site sewers and emergency sewer overflow). This novel modeling approach improves the interpretation of MST data, especially when fecal pollution from the same host group is released into the water source from different sites in the catchment.
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Affiliation(s)
- Ekaterina Sokolova
- Water Environment Technology, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden.
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36
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Almstrand R, Lydmark P, Sörensson F, Hermansson M. Nitrification potential and population dynamics of nitrifying bacterial biofilms in response to controlled shifts of ammonium concentrations in wastewater trickling filters. Bioresour Technol 2011; 102:7685-7691. [PMID: 21703852 DOI: 10.1016/j.biortech.2011.05.066] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2011] [Revised: 05/21/2011] [Accepted: 05/23/2011] [Indexed: 05/31/2023]
Abstract
Nitrogen removal in wastewater treatment is energy consuming and often carried out in biofilm nitrifying trickling filters (NTFs). We investigated nitrification potential and population dynamics of nitrifying bacteria in pilot-plant NTFs fed with full-scale plant wastewater with high (8-9 mg NH(4)(+)l(-1)) or low (<0.5mg NH(4)(+)l(-1)) ammonium concentrations. After ammonium shifts, nitrification potentials stabilized after 10-43 days depending on feed regime. An NTF fed with 3 days of high, and 4 days of low load per week reached a high nitrification potential, whereas a high load for 1 day a week gave a low potential. Nitrosomonas oligotropha dominated the AOB and changes in nitrification potentials were not explained by large population shifts to other AOBs. Although nitrification potentials were generally correlated with the relative amounts of AOB and NOB, this was not always the case. Ammonium feed strategies can be used to optimize wastewater treatment performance.
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Affiliation(s)
- R Almstrand
- Department of Cell and Molecular Biology/Microbiology, University of Gothenburg, Sweden
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Persson F, Svensson R, Nylund GM, Fredriksson NJ, Pavia H, Hermansson M. Ecological role of a seaweed secondary metabolite for a colonizing bacterial community. Biofouling 2011; 27:579-588. [PMID: 21660776 DOI: 10.1080/08927014.2011.589001] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Bacteria associated with seaweeds can both harm and benefit their hosts. Many seaweed species are known to produce compounds that inhibit growth of bacterial isolates, but the ecological role of seaweed metabolites for the associated bacterial community structure is not well understood. In this study the response of a colonizing bacterial community to the secondary metabolite (1,1,3,3-tetrabromo-2-heptanone) from the red alga Bonnemaisonia hamifera was investigated by using field panels coated with the metabolite at a range of concentrations covering those measured at the algal surface. The seaweed metabolite has previously been shown to have antibacterial effects. The metabolite significantly affected the natural fouling community by (i) altering the composition, (ii) altering the diversity by increasing the evenness and (iii) decreasing the density, as measured by terminal restriction fragment length polymorphism in conjunction with clone libraries of the 16S rRNA genes and by bacterial enumeration. No single major bacterial taxon (phylum, class) was particularly affected by the metabolite. Instead changes in community composition were observed at a more detailed phylogenetic level. This indicates a broad specificity of the seaweed metabolite against bacterial colonization, which is supported by the observation that the bacterial density was significantly affected at a lower concentration (0.02 μg cm⁻²) than the composition (1-2.5 μg cm⁻²) and the evenness (5 μg cm⁻²) of the bacterial communities. Altogether, the results emphasize the role of secondary metabolites for control of the density and structure of seaweed-associated bacterial communities.
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Affiliation(s)
- Frank Persson
- Department of Cell and Molecular Biology, Microbiology, University of Gothenburg, Goteborg, Sweden.
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Norberg P, Bergström M, Jethava V, Dubhashi D, Hermansson M. The IncP-1 plasmid backbone adapts to different host bacterial species and evolves through homologous recombination. Nat Commun 2011; 2:268. [PMID: 21468020 PMCID: PMC3104523 DOI: 10.1038/ncomms1267] [Citation(s) in RCA: 100] [Impact Index Per Article: 7.7] [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: 01/25/2011] [Accepted: 03/08/2011] [Indexed: 01/24/2023] Open
Abstract
Plasmids are important members of the bacterial mobile gene pool, and are among the most important contributors to horizontal gene transfer between bacteria. They typically harbour a wide spectrum of host beneficial traits, such as antibiotic resistance, inserted into their backbones. Although these inserted elements have drawn considerable interest, evolutionary information about the plasmid backbones, which encode plasmid related traits, is sparse. Here we analyse 25 complete backbone genomes from the broad-host-range IncP-1 plasmid family. Phylogenetic analysis reveals seven clades, in which two plasmids that we isolated from a marine biofilm represent a novel clade. We also found that homologous recombination is a prominent feature of the plasmid backbone evolution. Analysis of genomic signatures indicates that the plasmids have adapted to different host bacterial species. Globally circulating IncP-1 plasmids hence contain mosaic structures of segments derived from several parental plasmids that have evolved in, and adapted to, different, phylogenetically very distant host bacterial species. Plasmids are present in many bacteria and are often transferred between different species causing horizontal gene transfer. By comparing the sequences of 25 plasmid DNA backbones, the authors show that homologous recombination is prevalent in plasmids and that the plasmids have adapted to persist in different host bacteria.
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Affiliation(s)
- Peter Norberg
- Department of Cell and Molecular Biology, Microbiology, University of Gothenburg, Box 462, SE 413 46, Gothenburg, Sweden.
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Shaikh MF, Shenker N, Parker RA, Wajed J, Hermansson M, Axford J, Sofat N, Hayward J, Guglielmi S, Parker RA, Shenker N, Shaikh MF, Buerkle KS, Mulligan K, Hirani S, Kassoumeri L, Etheridge A, Wedderburn L, Newman S, Litwic AE, Jameson KA, Peveler R, Boucher BJ, Noonan K, Cooper C, Dennison E, Llewelyn K, Moscogiuri F, Gilbert A. Psychology, measurement and management of pain: 128. The Clinical Utility of Signs Associated with Cortical Reorganisation in Complex Regional Pain Sydrome. Rheumatology (Oxford) 2011. [DOI: 10.1093/rheumatology/ker159] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Nylund GM, Persson F, Lindegarth M, Cervin G, Hermansson M, Pavia H. The red alga Bonnemaisonia asparagoides regulates epiphytic bacterial abundance and community composition by chemical defence. FEMS Microbiol Ecol 2010; 71:84-93. [PMID: 19878319 DOI: 10.1111/j.1574-6941.2009.00791.x] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Ecological research on algal-derived metabolites with antimicrobial activity has recently received increased attention and is no longer only aimed at identifying novel natural compounds with potential use in applied perspectives. Despite this progress, few studies have so far demonstrated ecologically relevant antimicrobial roles of algal metabolites, and even fewer have utilized molecular tools to investigate the effects of these metabolites on the natural community composition of bacteria. In this study, we investigated whether the red alga Bonnemaisonia asparagoides is chemically defended against bacterial colonization of its surface by extracting surface-associated secondary metabolites and testing their antibacterial effects. Furthermore, we compared the associated bacterial abundance and community composition between B. asparagoides and two coexisting macroalgae. Surface extracts tested at natural concentrations had broad-spectrum effects on the growth of ecologically relevant bacteria, and consistent with this antibacterial activity, natural populations of B. asparagoides had significantly lower densities of epibacteria compared with the coexisting algae. Terminal restriction fragment length polymorphism analysis further showed that B. asparagoides harboured surface-associated bacteria with a community composition that was significantly different from those on coexisting macroalgae. Altogether, these findings demonstrate that B. asparagoides produces surface-bound antibacterial compounds with a significant impact on the abundance and composition of the associated bacterial community.
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Affiliation(s)
- Göran M Nylund
- Department of Marine Ecology-Tjärnö, University of Gothenburg, Tjärnö, Strömstad, Sweden.
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Makrygiannakis D, Hermansson M, Ulfgren AK, Nicholas AP, Zendman AJW, Eklund A, Grunewald J, Skold CM, Klareskog L, Catrina AI. Smoking increases peptidylarginine deiminase 2 enzyme expression in human lungs and increases citrullination in BAL cells. Ann Rheum Dis 2008; 67:1488-92. [PMID: 18413445 DOI: 10.1136/ard.2007.075192] [Citation(s) in RCA: 360] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
OBJECTIVES A gene-environment interaction between HLA-DR shared epitope genes and smoking in anti-cyclic citrullinated peptide antibody-positive rheumatoid arthritis (RA) has been reported. Identification of citrullinated proteins in bronchoalveolar lavage (BAL) cells from smokers has led to the suggestion that citrullination induced by smoking might be the first step in the pathogenic chain of RA. OBJECTIVE To confirm and extend these findings. METHODS Immunohistochemistry was performed on BAL cells and bronchial mucosal biopsy sections obtained through bronchoscopy from 14 healthy smokers and 16 healthy non-smokers. Two antibodies recognising citrullinated proteins, two antibodies recognising peptidylarginine deiminase (PAD)2 enzyme and one recognising PAD4 enzyme were used. RESULTS Citrullinated proteins are upregulated in BAL cells of healthy smokers compared with healthy non-smokers. This was associated with higher expression of the PAD2 enzyme. The same level of citrullinated proteins was present in bronchial mucosal biopsy specimens of healthy smokers and non-smokers, despite higher expression of PAD2 in smokers. CONCLUSION This study provides evidence that smoking enhances PAD2 expression in the bronchial mucosal and alveolar compartment, with consequent generation of citrullinated proteins in the latter. Smoking is an environmental factor that may lead to citrulline autoimmunity in genetically susceptible subjects.
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Affiliation(s)
- D Makrygiannakis
- Department of Medicine, Division of Rheumatology, Karolinska University Hospital, Solna, Karolinska Institutet, Stockholm, Sweden
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Wilén BM, Onuki M, Hermansson M, Lumley D, Mino T. Microbial community structure in activated sludge floc analysed by fluorescence in situ hybridization and its relation to floc stability. Water Res 2008; 42:2300-2308. [PMID: 18206208 DOI: 10.1016/j.watres.2007.12.013] [Citation(s) in RCA: 40] [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] [Received: 08/31/2007] [Revised: 12/11/2007] [Accepted: 12/14/2007] [Indexed: 05/25/2023]
Abstract
The efficiency of activated sludge treatment plants is dependent on the solid-liquid separation properties of the activated sludge. A critical parameter is the stability of the microbial flocs. Weak flocs deflocculate easily leaving increased concentrations of suspended solids in the effluent. The knowledge about how different bacteria are attached to the flocs and their influence on the bioflocculation is limited. In this study, the deflocculation of different phylogenetic groups of bacteria in activated sludge from a full scale plant was investigated. The experiments were carried out by using a shear method where the sludge flocs are deflocculated under controlled shear conditions. The degree of deflocculation was measured as increase in turbidity of the supernatant. Identification and quantification of the microbial community structure of both total activated sludge and deflocculated bacteria were conducted with group-specific gene probes for broad groups of bacteria (Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria and Actinobacteria) and fluorescence in situ hybridization (FISH). The microbial community structure of the deflocculated bacteria was different compared to the total activated sludge with a higher abundance of Gammaproteobacteria in the supernatant indicating that different groups of bacteria are bound with different strength to the floc surface. The results show that the bacteria in the outer parts of the flocs are relatively loosely bound to the floc matrix and can be easily eroded from the surface when exposed to shear.
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Affiliation(s)
- Britt-Marie Wilén
- Water Environment Technology, Chalmers University of Technology, Göteborg, Sweden.
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Lydmark P, Almstrand R, Samuelsson K, Mattsson A, Sörensson F, Lindgren PE, Hermansson M. Effects of environmental conditions on the nitrifying population dynamics in a pilot wastewater treatment plant. Environ Microbiol 2007; 9:2220-33. [PMID: 17686020 DOI: 10.1111/j.1462-2920.2007.01336.x] [Citation(s) in RCA: 71] [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] [Indexed: 11/28/2022]
Abstract
The effect of environmental conditions, especially ammonium concentration, on community composition and nitrification activity of nitrifying bacterial biofilms in a pilot wastewater treatment plant was examined. A decreasing ammonium gradient was created when four aerated tanks with suspended carrier material were serially fed with wastewater. Community composition was analysed using fluorescence in situ hybridization (FISH) probes as well as partial 16S rRNA and amoA gene analysis using polymerase chain reaction-denaturating gradient gel electrophoresis (PCR-DGGE) and sequencing. Fluorescence in situ hybridization probes identified at least five ammonia-oxidizing bacterial (AOB) and two nitrite-oxidizing bacterial (NOB) populations. A change in nitrifying community was detected in the tanks, indicating that ammonium was an important structuring factor. Further, we found support for different autoecology within the Nitrosomonas oligotropha lineage, as at least one population within this lineage increased in relative abundance with ammonium concentration while another population decreased. Absolute numbers of AOB and NOB growing in biofilms on the carriers were determined and the cell specific nitrification rates calculated seemed strongly correlated to ammonium concentration. Oxygen could also be limiting in the biofilms of the first tank with high ammonium concentrations. The response of the nitrifying community to increased ammonium concentrations differed between the tanks, indicating that activity correlates with community structure.
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Affiliation(s)
- Pär Lydmark
- Department of Cell and Molecular Biology, Microbiology, Göteborg University, Göteborg, Sweden
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Ojala PJ, Hirvonen TE, Hermansson M, Somerharju P, Parkkinen J. Acyl chain-dependent effect of lysophosphatidylcholine on human neutrophils. J Leukoc Biol 2007; 82:1501-9. [PMID: 17884992 DOI: 10.1189/jlb.0507292] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.5] [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: 12/16/2022] Open
Abstract
Lysophosphatidylcholine (LPC) is the most abundant lysophospholipid in plasma and tissues, and its level increases in ischemia and inflammation. LPC induces various proinflammatory actions in leukocytes, endothelial cells, and smooth muscle cells, but its effects may vary, depending on the acyl chain. In the present study, we identified the molecular species of LPC in human plasma and studied their effects on human neutrophils. Unsaturated LPC species over a wide concentration range (5-200 microM) induced long-lasting superoxide production in neutrophils. The response was preceded by a >10-min lag time and lasted for 60-90 min. Superoxide production was prevented when albumin was added together with LPC at a molar ratio of 1:2 or higher, and significant inhibition was observed even when albumin was added 4-8 min after LPC. Saturation of albumin by fivefold molar excess of stearic acid reduced the inhibitory effect significantly. Saturated LPCs, particularly the most abundant 16:0 species, induced significantly less superoxide production than the unsaturated species and only at 5-10 microM concentrations. Saturated LPC species elicited a several-fold higher increase in cytoplasmic calcium and at >20 microM, increased plasma membrane permeability. A mixture of LPCs mimicking the plasma LPC composition induced nearly similar superoxide production as the most active LPC18:1 alone. These results indicate remarkable acyl chain-dependent differences in the cellular effects of LPC. Elevation of LPC level may increase inflammation through activation of neutrophil NADPH oxidase, particularly when the simultaneous increase of free fatty acids diminishes the ability of albumin to scavenge LPCs.
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Affiliation(s)
- P J Ojala
- Finnish Red Cross Blood Service, Helsinki, Finland
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Kämpfer P, Rosselló-Mora R, Hermansson M, Persson F, Huber B, Falsen E, Busse HJ. Undibacterium pigrum gen. nov., sp. nov., isolated from drinking water. Int J Syst Evol Microbiol 2007; 57:1510-1515. [PMID: 17625185 DOI: 10.1099/ijs.0.64785-0] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.1] [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: 11/18/2022] Open
Abstract
Two Gram-negative, rod-shaped, oxidase-positive, non-spore-forming, non-motile bacteria (strains CCUG 49009T and CCUG 49012), both isolated from drinking water, were characterized. On the basis of chemotaxonomic data [major ubiquinone, Q-8; predominant polyamines, putrescine and 2-hydroxyputrescine; major polar lipids, phosphatidylethanolamine, moderate amounts of diphosphatidylglycerol and phosphatidylglycerol and minor amounts of three aminolipids and phosphatidylserine; major fatty acids, C16 : 0 and summed feature 3 (C16 : 1
ω7c/C15 : 0 iso 2-OH)] and 16S rRNA gene sequence similarities, both strains clearly belong to the family Oxalobacteraceae of the Betaproteobacteria. 16S rRNA gene sequence similarities with members of the most closely related genera of this group (Herminiimonas, Massilia, Duganella, Telluria, Herbaspirillum, Janthinobacterium, Naxibacter and Paucimonas) were less than 96.5 % for both strains. The two strains also shared a relatively low 16S rRNA gene sequence similarity (96.8 %). Although phylogenetic analysis based on 16S rRNA gene sequence similarities clearly showed that the two organisms formed a separate branch, their phenotypes (including chemotaxonomic features) were hardly distinguishable and showed high similarities to those reported for the most closely related genera. On the basis of DNA–DNA hybridization results, the two strains were shown to represent separate species (sharing only 20 % DNA–DNA relatedness), but they could not be clearly differentiated phenotypically from each other. It is evident that these organisms represent a new genus, Undibacterium gen. nov., with one species, Undibacterium pigrum sp. nov. The type strain of Undibacterium pigrum is strain CCUG 49009T (=CIP 109318T). Strain CCUG 49012 (=CIP 108976) probably represents a second species of this genus, but is described here as a second genomovar of this species because of the lack of differentiating characters.
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MESH Headings
- Betaproteobacteria
- Chromatography, Thin Layer
- DNA, Bacterial/chemistry
- DNA, Bacterial/genetics
- DNA, Ribosomal/chemistry
- DNA, Ribosomal/genetics
- Fatty Acids/analysis
- Fresh Water/microbiology
- Genes, rRNA
- Germany
- Molecular Sequence Data
- Nucleic Acid Hybridization
- Oxalobacteraceae/chemistry
- Oxalobacteraceae/classification
- Oxalobacteraceae/genetics
- Oxalobacteraceae/isolation & purification
- Phospholipids/analysis
- Phylogeny
- Polyamines/analysis
- RNA, Bacterial/genetics
- RNA, Ribosomal, 16S/genetics
- Sequence Analysis, DNA
- Sequence Homology, Nucleic Acid
- Ubiquinone/analysis
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Affiliation(s)
- Peter Kämpfer
- Institut für Angewandte Mikrobiologie, Justus-Liebig-Universität Giessen, D-35392 Giessen, Germany
| | - Ramon Rosselló-Mora
- Institut Mediterrani d'Estudis Avancats (CSIC-UIB), E-07190 Esporles, Mallorca, Spain
| | - Malte Hermansson
- Department of Cell and Molecular Biology, Göteborg University, Sweden
| | - Frank Persson
- Department of Cell and Molecular Biology, Göteborg University, Sweden
| | - Birgit Huber
- Institut für Bakteriologie, Mykologie und Hygiene, Veterinärmedizinische Universität, A-1210 Wien, Austria
| | - Enevold Falsen
- Culture Collection University Göteborg, Department of Clinical Bacteriology, S-41346 Göteborg, Sweden
| | - Hans-Jürgen Busse
- Institut für Bakteriologie, Mykologie und Hygiene, Veterinärmedizinische Universität, A-1210 Wien, Austria
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Persson F, Heinicke G, Hedberg T, Hermansson M, Uhl W. Removal of geosmin and MIB by biofiltration--an investigation discriminating between adsorption and biodegradation. Environ Technol 2007; 28:95-104. [PMID: 17283953 DOI: 10.1080/09593332808618770] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [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
Geosmin and 2-methylisoborneol (MIB) are two substances causing earthy/musty odours that are difficult to remove by conventional chemical drinking water treatment. In this study removal of geosmin and MIB by biofiltration of untreated surface water was investigated using granular activated carbon (GAC) and crushed expanded clay (EC) as filter media. Biofiltration through both GAC and EC removed geosmin and MIB present at low (20 ng l(-1)) concentrations by at least 97% at an empty bed contact time of 30 minutes and a temperature of 15 degrees C. At lower temperature (6-12 degrees C) and simultaneously lower biomass concentrations, removal efficiency was similar in the GAC but considerably lower in the EC biofilter, pointing to a second mechanism different from biodegradation. Consequently, microbial activity was suppressed with azide to enable discrimination between biodegradation and adsorption. During azide dosage, the GAC biofilters still removed geosmin and MIB nearly unaffectedly. In the EC biofilter, however, removal of both odorants ceased completely. Methylene blue adsorption confirmed that the GAC, even after almost four years of operation receiving surface water, had capacity to remove geosmin and MIB by adsorption. Since odour episodes commonly occur during the warm season when microbiological activity is high, EC constitutes a viable option as carrier medium for direct biological filtration of surface water. The additional GAC adsorption capacity however adds robustness to the removal process.
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Affiliation(s)
- F Persson
- Cell and Molecular Biology, Microbiology, Göteborg University, Sweden
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Lydmark P, Lind M, Sörensson F, Hermansson M. Vertical distribution of nitrifying populations in bacterial biofilms from a full-scale nitrifying trickling filter. Environ Microbiol 2006; 8:2036-49. [PMID: 17014502 DOI: 10.1111/j.1462-2920.2006.01085.x] [Citation(s) in RCA: 50] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Cryosectioned biofilm from three depths (0.5, 3.0 and 6.0 m) in a full-scale nitrifying trickling filter (NTF) were studied using fluorescence in situ hybridization (FISH). A large number of sections were used to determine how the biofilm thickness, structure and community composition varied with depth along the ammonium concentration gradient in the NTF, and how the ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) were distributed vertically within the biofilm. Both the biofilm thickness and relative biomass content of the biofilm decreased with depth, along with structural differences such as void size and surface roughness. Four AOB populations were found, with two Nitrosomonas oligotropha populations dominating at all depths. A smaller population of Nitrosomonas europaea was present only at 0.5 m, while a population of Nitrosomonas communis increased with depth. The two N. oligotropha populations showed different vertical distribution patterns within the biofilm, indicating different ecophysiologies even though they belong to the same AOB lineage. All NOB were identified as Nitrospira sp., and were generally more associated with the biofilm base than the surface-associated dominating AOB population. Additionally, a small population of anaerobic ammonia-oxidizers was found at 6.0 m, even though the biofilm was well aerated.
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Affiliation(s)
- Pär Lydmark
- Department of Cell and Molecular Biology, Microbiology, Göteborg University, Box 462, SE-40530, Göteborg, Sweden.
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Persson F, Heinicke G, Uhl W, Hedberg T, Hermansson M. Performance of direct biofiltration of surface water for reduction of biodegradable organic matter and biofilm formation potential. Environ Technol 2006; 27:1037-45. [PMID: 17067130 DOI: 10.1080/09593332708618717] [Citation(s) in RCA: 24] [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: 05/12/2023]
Abstract
Direct biofiltration of surface water may be considered as pre-treatment for membrane filtration, in order to reduce fouling. The biofiltration process was investigated with regard to biodegradable organic matter and biofilm formation, covering the annual variations under moderately cold climate conditions. Granular activated carbon (GAC) and two types of crushed expanded clay (EC) were compared as filter media. To assess the biological properties of the biofilters, viable biomass and respiratory activity was examined. Biofiltration removed assimilable organic carbon (AOC) and biodegradable dissolved organic carbon (BDOC) by about 30% and also reduced the bacterial concentration in the water phase. Also, biofilm formation in the treated water was reduced by 80-90% during summer and winter conditions. The reductions in the investigated parameters were similar in the biofilters with GAC and EC. Likewise, a similar amount and development of biomass was found in the GAC and EC biofilters of comparable grain size with a pronounced stratification from top to bottom of the filter bed. The specific respiratory activity of the biofilter biomass was dependent on raw water temperature. Even though slight correlations between BDOC removal and temperature or respiratory activity were observed, AOC and BDOC removals were mainly dependent on the feed water concentrations of these compounds. The results indicate that direct biofiltration of surface water, by reducing AOC, BDOC and biofilm formation in the water, may be an advantageous pre-treatment for membrane filtration processes.
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Affiliation(s)
- F Persson
- CMB Microbiology, Göteborg University, Göteborg, Sweden
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Dalevi D, Dubhashi D, Hermansson M. A new order estimator for fixed and variable length Markov models with applications to DNA sequence similarity. Stat Appl Genet Mol Biol 2006; 5:Article8. [PMID: 16646872 DOI: 10.2202/1544-6115.1214] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [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: 11/18/2022]
Abstract
Recently Peres and Shields discovered a new method for estimating the order of a stationary fixed order Markov chain. They showed that the estimator is consistent by proving a threshold result. While this threshold is valid asymptotically in the limit, it is not very useful for DNA sequence analysis where data sizes are moderate. In this paper we give a novel interpretation of the Peres-Shields estimator as a sharp transition phenomenon. This yields a precise and powerful estimator that quickly identifies the core dependencies in data. We show that it compares favorably to other estimators, especially in the presence of variable dependencies. Motivated by this last point, we extend the Peres-Shields estimator to Variable Length Markov Chains. We compare it to a well-established estimator and show that it is superior in terms of the predictive likelihood. We give an application to the problem of detecting DNA sequence similarity in plasmids.
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