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Wachira JM, Kiplimo D, Thuita M, Masso C, Mwirichia R. Community Structure of Nitrifying and Denitrifying Bacteria from Effluents Discharged into Lake Victoria, Kenya. Curr Microbiol 2022; 79:252. [PMID: 35834125 DOI: 10.1007/s00284-022-02950-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Accepted: 06/23/2022] [Indexed: 11/26/2022]
Abstract
An active microbial community of nitrifying and denitrifying bacteria is needed for efficient utilization of nitrogenous compounds from wastewater. In this study, we explored the bacterial community diversity and structure within rivers, treated and untreated wastewater treatment plants (WWTPs) discharging into Lake Victoria. Water samples were collected from rivers and WWTPs that drain into Lake Victoria. Physicochemical analysis was done to determine the level of nutrients or pollutant loading in the samples. Total community DNA was extracted, followed by Illumina high throughput sequencing to determine the total microbial community and abundance. Enrichment and isolation were then done to recover potential nitrifiers and denitrifiers. Physicochemical analysis pointed to high levels total nitrogen and ammonia in both treated and untreated WWTPs as compared to the samples from the lake and rivers. A total of 1,763 operational taxonomic units (OTUs) spread across 26 bacterial phyla were observed with the most dominant phylum being Proteobacteria. We observed a decreasing trend in diversity from the lake, rivers to WWTPs. The genus Planktothrix constituted 19% of the sequence reads in sample J2 collected from the lagoon. All the isolates recovered in this study were affiliated to three genera: Pseudomonas, Klebsiella and Enterobacter in the phylum Proteobacteria. A combination of metagenomic analysis and a culture-dependent approach helped us understand the relative abundance as well as potential nitrifiers and denitrifiers present in different samples. The recovered isolates could be used for in situ removal of nitrogenous compounds from contaminated wastewater.
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Affiliation(s)
- James M Wachira
- Department of Biological Sciences, University of Embu, Embu, 6-60100, Kenya
| | - Denis Kiplimo
- Department of Biological Sciences, University of Embu, Embu, 6-60100, Kenya
| | - Moses Thuita
- International Institute of Tropical Agriculture, Nairobi, 30772-00100, Kenya
| | - Cargele Masso
- International Institute of Tropical Agriculture, PMB 5320, Ibadan, 200001, Oyo State, Nigeria
| | - Romano Mwirichia
- Department of Biological Sciences, University of Embu, Embu, 6-60100, Kenya.
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Compositional and Metabolic Responses of Autotrophic Microbial Community to Salinity in Lacustrine Environments. mSystems 2022; 7:e0033522. [PMID: 35862818 PMCID: PMC9426519 DOI: 10.1128/msystems.00335-22] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The compositional and physiological responses of autotrophic microbiotas to salinity in lakes remain unclear. In this study, the community composition and carbon fixation pathways of autotrophic microorganisms in lacustrine sediments with a salinity gradient (82.6 g/L to 0.54 g/L) were investigated by using metagenomic analysis. A total of 117 metagenome-assembled genomes (MAGs) with carbon fixation potentially belonging to 20 phyla were obtained. The abundance of these potential autotrophs increased significantly with decreasing salinity, and the variation of sediment autotrophic microbial communities was mainly affected by salinity, pH, and total organic carbon. Notably, along the decreasing salinity gradient, the dominant lineage shifted from Desulfobacterota to Proteobacteria. Meanwhile, the dominant carbon fixation pathway shifted from the Wood-Lungdahl pathway to the less-energy-efficient Calvin-Benson-Bassham cycle, with glycolysis shifting from the Embden-Meyerhof-Parnas pathway to the less-exergonic Entner-Doudoroff pathway. These results suggest that the physiological efficiency of autotrophic microorganisms decreased when the environmental salinity became lower. Metabolic inference of these MAGs revealed that carbon fixation may be coupled to the oxidation of reduced sulfur compounds and ferrous iron, dissimilatory nitrate reduction at low salinity, and dissimilatory sulfate reduction in hypersaline sediments. These results extend our understanding of metabolic versatility and niche diversity of autotrophic microorganisms in saline environments and shed light on the response of autotrophic microbiomes to salinity. These findings are of great significance for understanding the impact of desalination caused by climate warming on the carbon cycle of saline lake ecosystems. IMPORTANCE The Qinghai-Tibetan lakes are experiencing water increase and salinity decrease due to climate warming. However, little is known about how the salinity decrease will affect the composition of autotrophic microbial populations and their carbon fixation pathways. In this study, we used genome-resolved metagenomics to interpret the dynamic changes in the autotrophic microbial community and metabolic pathways along a salinity gradient. The results showed that desalination drove the shift of the dominant microbial lineage from Desulfobacterota to Proteobacteria, enriched autotrophs with lower physiological efficiency pathways, and enhanced coupling between the carbon cycle and other element cycles. These results can predict the future response of microbial communities to lake desalination and improve our understanding of the effect of climate warming on the carbon cycle in saline aquatic ecosystems.
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Blohm A, Kumar S, Knebl A, Herrmann M, Küsel K, Popp J, Frosch T. Activity and electron donor preference of two denitrifying bacterial strains identified by Raman gas spectroscopy. Anal Bioanal Chem 2021; 414:601-611. [PMID: 34297136 PMCID: PMC8748363 DOI: 10.1007/s00216-021-03541-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2021] [Revised: 07/06/2021] [Accepted: 07/08/2021] [Indexed: 11/26/2022]
Abstract
Human activities have greatly increased the input of reactive nitrogen species into the environment and disturbed the balance of the global N cycle. This imbalance may be offset by bacterial denitrification, an important process in maintaining the ecological balance of nitrogen. However, our understanding of the activity of mixotrophic denitrifying bacteria is not complete, as most research has focused on heterotrophic denitrification. The aim of this study was to investigate substrate preferences for two mixotrophic denitrifying bacterial strains, Acidovorax delafieldii and Hydrogenophaga taeniospiralis, under heterotrophic, autotrophic or mixotrophic conditions. This complex analysis was achieved by simultaneous identification and quantification of H2, O2, CO2, 14N2, 15N2 and 15N2O in course of the denitrification process with help of cavity-enhanced Raman spectroscopic (CERS) multi-gas analysis. To disentangle electron donor preferences for both bacterial strains, microcosm-based incubation experiments under varying substrate conditions were conducted. We found that Acidovorax delafieldii preferentially performed heterotrophic denitrification in the mixotrophic sub-experiments, while Hydrogenophaga taeniospiralis preferred autotrophic denitrification in the mixotrophic incubation. These observations were supported by stoichiometric calculations. The results demonstrate the prowess of advanced Raman multi-gas analysis to study substrate use and electron donor preferences in denitrification, based on the comprehensive quantification of complex microbial gas exchange processes.
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Affiliation(s)
- Annika Blohm
- Leibniz Institute of Photonic Technology, 07745, Jena, Germany
| | - Swatantar Kumar
- Institute of Biodiversity, Friedrich Schiller University Jena, 07743, Jena, Germany
| | - Andreas Knebl
- Leibniz Institute of Photonic Technology, 07745, Jena, Germany
| | - Martina Herrmann
- Institute of Biodiversity, Friedrich Schiller University Jena, 07743, Jena, Germany
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, 04103, Leipzig, Germany
| | - Kirsten Küsel
- Institute of Biodiversity, Friedrich Schiller University Jena, 07743, Jena, Germany
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, 04103, Leipzig, Germany
| | - Jürgen Popp
- Leibniz Institute of Photonic Technology, 07745, Jena, Germany
- Institute of Physical Chemistry, Friedrich Schiller University Jena, 07743, Jena, Germany
- Abbe Centre of Photonics, Friedrich Schiller University, 07743, Jena, Germany
| | - Torsten Frosch
- Leibniz Institute of Photonic Technology, 07745, Jena, Germany.
- Institute of Physical Chemistry, Friedrich Schiller University Jena, 07743, Jena, Germany.
- Abbe Centre of Photonics, Friedrich Schiller University, 07743, Jena, Germany.
- Biophotonics and Biomedical Engineering Group, Technical University Darmstadt, Merckstraße 25, 64283, Darmstadt, Germany.
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Castaño A, Prosenkov A, Baragaño D, Otaegui N, Sastre H, Rodríguez-Valdés E, Gallego JLR, Peláez AI. Effects of in situ Remediation With Nanoscale Zero Valence Iron on the Physicochemical Conditions and Bacterial Communities of Groundwater Contaminated With Arsenic. Front Microbiol 2021; 12:643589. [PMID: 33815330 PMCID: PMC8010140 DOI: 10.3389/fmicb.2021.643589] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Accepted: 02/25/2021] [Indexed: 12/31/2022] Open
Abstract
Nanoscale Zero-Valent Iron (nZVI) is a cost-effective nanomaterial that is widely used to remove a broad range of metal(loid)s and organic contaminants from soil and groundwater. In some cases, this material alters the taxonomic and functional composition of the bacterial communities present in these matrices; however, there is no conclusive data that can be generalized to all scenarios. Here we studied the effect of nZVI application in situ on groundwater from the site of an abandoned fertilizer factory in Asturias, Spain, mainly polluted with arsenic (As). The geochemical characteristics of the water correspond to a microaerophilic and oligotrophic environment. Physico-chemical and microbiological (cultured and total bacterial diversity) parameters were monitored before and after nZVI application over six months. nZVI treatment led to a marked increase in Fe(II) concentration and a notable fall in the oxidation-reduction potential during the first month of treatment. A substantial decrease in the concentration of As during the first days of treatment was observed, although strong fluctuations were subsequently detected in most of the wells throughout the six-month experiment. The possible toxic effects of nZVI on groundwater bacteria could not be clearly determined from direct observation of those bacteria after staining with viability dyes. The number of cultured bacteria increased during the first two weeks of the treatment, although this was followed by a continuous decrease for the following two weeks, reaching levels moderately below the initial number at the end of sampling, and by changes in their taxonomic composition. Most bacteria were tolerant to high As(V) concentrations and showed the presence of diverse As resistance genes. A more complete study of the structure and diversity of the bacterial community in the groundwater using automated ribosomal intergenic spacer analysis (ARISA) and sequencing of the 16S rRNA amplicons by Illumina confirmed significant alterations in its composition, with a reduction in richness and diversity (the latter evidenced by Illumina data) after treatment with nZVI. The anaerobic conditions stimulated by treatment favored the development of sulfate-reducing bacteria, thereby opening up the possibility to achieve more efficient removal of As.
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Affiliation(s)
- Ana Castaño
- Area of Microbiology, Department of Functional Biology and Environmental Biogeochemistry and Raw Materials Group, University of Oviedo, Oviedo, Spain
| | - Alexander Prosenkov
- Area of Microbiology, Department of Functional Biology and Environmental Biogeochemistry and Raw Materials Group, University of Oviedo, Oviedo, Spain
| | - Diego Baragaño
- INDUROT and Environmental Biogeochemistry and Raw Materials Group, Campus of Mieres, University of Oviedo, Mieres, Spain
| | - Nerea Otaegui
- TECNALIA, Basque Research and Technology Alliance (BRTA), Parque Tecnológico de Bizkaia, Derio, Spain
| | - Herminio Sastre
- Department of Chemical and Environmental Engineering and Environmental Biogeochemistry and Raw Materials Group, University of Oviedo, Oviedo, Spain
| | - Eduardo Rodríguez-Valdés
- INDUROT and Environmental Biogeochemistry and Raw Materials Group, Campus of Mieres, University of Oviedo, Mieres, Spain
| | - José Luis R Gallego
- INDUROT and Environmental Biogeochemistry and Raw Materials Group, Campus of Mieres, University of Oviedo, Mieres, Spain
| | - Ana Isabel Peláez
- Area of Microbiology, Department of Functional Biology and Environmental Biogeochemistry and Raw Materials Group, University of Oviedo, Oviedo, Spain.,University Institute of Biotechnology of Asturias (IUBA), University of Oviedo, Oviedo, Spain
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Asplund-Samuelsson J, Hudson EP. Wide range of metabolic adaptations to the acquisition of the Calvin cycle revealed by comparison of microbial genomes. PLoS Comput Biol 2021; 17:e1008742. [PMID: 33556078 PMCID: PMC7895386 DOI: 10.1371/journal.pcbi.1008742] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Revised: 02/19/2021] [Accepted: 01/25/2021] [Indexed: 11/21/2022] Open
Abstract
Knowledge of the genetic basis for autotrophic metabolism is valuable since it relates to both the emergence of life and to the metabolic engineering challenge of incorporating CO2 as a potential substrate for biorefining. The most common CO2 fixation pathway is the Calvin cycle, which utilizes Rubisco and phosphoribulokinase enzymes. We searched thousands of microbial genomes and found that 6.0% contained the Calvin cycle. We then contrasted the genomes of Calvin cycle-positive, non-cyanobacterial microbes and their closest relatives by enrichment analysis, ancestral character estimation, and random forest machine learning, to explore genetic adaptations associated with acquisition of the Calvin cycle. The Calvin cycle overlaps with the pentose phosphate pathway and glycolysis, and we could confirm positive associations with fructose-1,6-bisphosphatase, aldolase, and transketolase, constituting a conserved operon, as well as ribulose-phosphate 3-epimerase, ribose-5-phosphate isomerase, and phosphoglycerate kinase. Additionally, carbohydrate storage enzymes, carboxysome proteins (that raise CO2 concentration around Rubisco), and Rubisco activases CbbQ and CbbX accompanied the Calvin cycle. Photorespiration did not appear to be adapted specifically for the Calvin cycle in the non-cyanobacterial microbes under study. Our results suggest that chemoautotrophy in Calvin cycle-positive organisms was commonly enabled by hydrogenase, and less commonly ammonia monooxygenase (nitrification). The enrichment of specific DNA-binding domains indicated Calvin-cycle associated genetic regulation. Metabolic regulatory adaptations were illustrated by negative correlation to AraC and the enzyme arabinose-5-phosphate isomerase, which suggests a downregulation of the metabolite arabinose-5-phosphate, which may interfere with the Calvin cycle through enzyme inhibition and substrate competition. Certain domains of unknown function that were found to be important in the analysis may indicate yet unknown regulatory mechanisms in Calvin cycle-utilizing microbes. Our gene ranking provides targets for experiments seeking to improve CO2 fixation, or engineer novel CO2-fixing organisms.
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Affiliation(s)
- Johannes Asplund-Samuelsson
- Science for Life Laboratory, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, Solna, Sweden
| | - Elton P. Hudson
- Science for Life Laboratory, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, Solna, Sweden
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Nitz H, Duarte M, Jauregui R, Pieper DH, Müller JA, Kästner M. Identification of benzene-degrading Proteobacteria in a constructed wetland by employing in situ microcosms and RNA-stable isotope probing. Appl Microbiol Biotechnol 2019; 104:1809-1820. [DOI: 10.1007/s00253-019-10323-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Revised: 11/30/2019] [Accepted: 12/15/2019] [Indexed: 11/24/2022]
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Kumar S, Herrmann M, Blohm A, Hilke I, Frosch T, Trumbore SE, Küsel K. Thiosulfate- and hydrogen-driven autotrophic denitrification by a microbial consortium enriched from groundwater of an oligotrophic limestone aquifer. FEMS Microbiol Ecol 2018; 94:5056153. [DOI: 10.1093/femsec/fiy141] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2018] [Accepted: 07/18/2018] [Indexed: 01/17/2023] Open
Affiliation(s)
- Swatantar Kumar
- Aquatic Geomicrobiology, Institute of Biodiversity, Friedrich Schiller University Jena, Dornburger Strasse 159, D-07743 Jena, Germany
- Max Planck Institute for Biogeochemistry, Hans-Knöll-Strasse 10, D-07745 Jena, Germany
| | - Martina Herrmann
- Aquatic Geomicrobiology, Institute of Biodiversity, Friedrich Schiller University Jena, Dornburger Strasse 159, D-07743 Jena, Germany
- German Center for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Deutscher Platz 5e, D-04103 Leipzig, Germany
| | - Annika Blohm
- Max Planck Institute for Biogeochemistry, Hans-Knöll-Strasse 10, D-07745 Jena, Germany
- Leibniz Institute of Photonic Technology, Albert-Einstein-Strasse 9, D-07745 Jena, Germany
| | - Ines Hilke
- Max Planck Institute for Biogeochemistry, Hans-Knöll-Strasse 10, D-07745 Jena, Germany
| | - Torsten Frosch
- Leibniz Institute of Photonic Technology, Albert-Einstein-Strasse 9, D-07745 Jena, Germany
- Institute of Physical Chemistry and Abbe Center of Photonics, Albert-Einstein-Strasse 6, D-07745, Jena, Germany
| | - Susan E Trumbore
- Max Planck Institute for Biogeochemistry, Hans-Knöll-Strasse 10, D-07745 Jena, Germany
| | - Kirsten Küsel
- Aquatic Geomicrobiology, Institute of Biodiversity, Friedrich Schiller University Jena, Dornburger Strasse 159, D-07743 Jena, Germany
- German Center for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Deutscher Platz 5e, D-04103 Leipzig, Germany
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