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Fu K, Bian Y, Yang F, Liao M, Xu J, Qiu F. Influencing factors on the activity of an enriched Nitrospira culture with granular morphology. ENVIRONMENTAL TECHNOLOGY 2024; 45:4607-4621. [PMID: 37712531 DOI: 10.1080/09593330.2023.2260122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Accepted: 09/09/2023] [Indexed: 09/16/2023]
Abstract
Nitrospira is a common genus of nitrite-oxidising bacteria (NOB) found in wastewater treatment plants (WWTPs). To identify the key factors influencing the composition of NOB communities, research was conducted using both sequencing batch reactor (SBR) and continuous flow reactor under different conditions. High-throughput 16S rRNA gene sequencing revealed that Nitrospira (18.79% in R1 and 25.77% in R3) was the dominant NOB under low dissolved oxygen (DO) and low nitrite (NO 2 - -N) concentrations, while Nitrobacter (21.26% in R2) was the dominant NOB under high DO and high NO 2 - -N concentrations. Flocculent and granule sludge were cultivated with Nitrospira as the dominant genus. Compared to Nitrospira flocculent sludge, Nitrospira granule sludge had higher inhibition threshold concentrations for free ammonia (FA) and free nitrous acid (FNA). It was more likely to resist adverse environmental disturbances. Furthermore, the effects of environmental factors such as temperature, pH, and DO on the activity of Nitrospira granular sludge were also studied. The results showed that the optimum temperature and pH for Nitrospira granular sludge were 36°C and 7.0, respectively. Additionally, Nitrospira granular sludge showed a higher dissolved oxygen half-saturation constant (Ko) of 3.67 ± 0.71 mg/L due to its morphological characteristics. However, the majority of WWTPs conditions do not meet the conditions for the Nitrospira granular sludge. Thus, it can be speculated that future development of aerobic partial nitrification granular sludge may automatically eliminate the influence of Nitrospira. This study provides a theoretical basis for a deeper understanding of Nitrospira and the development of future water treatment processes.
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Affiliation(s)
- Kunming Fu
- Key Laboratory of Urban Storm Water System and Water Environment Ministry of Education, Beijing University of Civil Engineering and Architecture, Beijing, People's Republic of China
- Sino-Dutch R&D Centre for Future Wastewater Treatment Technologies/Key Laboratory of Urban Stormwater System and Water Environment, Beijing University of Civil Engineering and Architecture, Beijing, People's Republic of China
| | - Yihao Bian
- Key Laboratory of Urban Storm Water System and Water Environment Ministry of Education, Beijing University of Civil Engineering and Architecture, Beijing, People's Republic of China
- Sino-Dutch R&D Centre for Future Wastewater Treatment Technologies/Key Laboratory of Urban Stormwater System and Water Environment, Beijing University of Civil Engineering and Architecture, Beijing, People's Republic of China
| | - Fan Yang
- Key Laboratory of Urban Storm Water System and Water Environment Ministry of Education, Beijing University of Civil Engineering and Architecture, Beijing, People's Republic of China
- Sino-Dutch R&D Centre for Future Wastewater Treatment Technologies/Key Laboratory of Urban Stormwater System and Water Environment, Beijing University of Civil Engineering and Architecture, Beijing, People's Republic of China
| | - Minhui Liao
- Powerchina Eco-environmental Group Co., Ltd, Shenzhen, China
| | - Jian Xu
- Key Laboratory of Urban Storm Water System and Water Environment Ministry of Education, Beijing University of Civil Engineering and Architecture, Beijing, People's Republic of China
- Sino-Dutch R&D Centre for Future Wastewater Treatment Technologies/Key Laboratory of Urban Stormwater System and Water Environment, Beijing University of Civil Engineering and Architecture, Beijing, People's Republic of China
| | - Fuguo Qiu
- Key Laboratory of Urban Storm Water System and Water Environment Ministry of Education, Beijing University of Civil Engineering and Architecture, Beijing, People's Republic of China
- Sino-Dutch R&D Centre for Future Wastewater Treatment Technologies/Key Laboratory of Urban Stormwater System and Water Environment, Beijing University of Civil Engineering and Architecture, Beijing, People's Republic of China
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2
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Alfreider A, Harringer M. Vertical Distribution and Seasonal Patterns of Candidatus Nitrotoga in a Sub-Alpine Lake. Microbes Environ 2024; 39:ME23086. [PMID: 38825479 PMCID: PMC11220445 DOI: 10.1264/jsme2.me23086] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Accepted: 03/01/2024] [Indexed: 06/04/2024] Open
Abstract
The nitrite oxidizing bacterial genus Ca. Nitrotoga was only recently discovered to be widespread in freshwater systems; however, limited information is currently available on the environmental factors and seasonal effects that influence its distribution in lakes. In a one-year study in a dimictic lake, based on monthly sampling along a vertical profile, the droplet digital PCR quantification of Ca. Nitrotoga showed a strong spatio-temporal patchiness. A correlation ana-lysis with environmental parameters revealed that the abundance of Ca. Nitrotoga correlated with dissolved oxygen and ammonium, suggesting that the upper hypolimnion of the lake is the preferred habitat.
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Affiliation(s)
- Albin Alfreider
- Department of Ecology, University of Innsbruck, Technikerstrasse 25, 6020 Innsbruck, Austria
| | - Manuel Harringer
- Department of Ecology, University of Innsbruck, Technikerstrasse 25, 6020 Innsbruck, Austria
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3
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Kop LFM, Koch H, Jetten MSM, Daims H, Lücker S. Metabolic and phylogenetic diversity in the phylum Nitrospinota revealed by comparative genome analyses. ISME COMMUNICATIONS 2024; 4:ycad017. [PMID: 38317822 PMCID: PMC10839748 DOI: 10.1093/ismeco/ycad017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/07/2023] [Revised: 12/22/2023] [Accepted: 12/22/2023] [Indexed: 02/07/2024]
Abstract
The most abundant known nitrite-oxidizing bacteria in the marine water column belong to the phylum Nitrospinota. Despite their importance in marine nitrogen cycling and primary production, there are only few cultured representatives that all belong to the class Nitrospinia. Moreover, although Nitrospinota were traditionally thought to be restricted to marine environments, metagenome-assembled genomes have also been recovered from groundwater. Over the recent years, metagenomic sequencing has led to the discovery of several novel classes of Nitrospinota (UBA9942, UBA7883, 2-12-FULL-45-22, JACRGO01, JADGAW01), which remain uncultivated and have not been analyzed in detail. Here, we analyzed a nonredundant set of 98 Nitrospinota genomes with focus on these understudied Nitrospinota classes and compared their metabolic profiles to get insights into their potential role in biogeochemical element cycling. Based on phylogenomic analysis and average amino acid identities, the highly diverse phylum Nitrospinota could be divided into at least 33 different genera, partly with quite distinct metabolic capacities. Our analysis shows that not all Nitrospinota are nitrite oxidizers and that members of this phylum have the genomic potential to use sulfide and hydrogen for energy conservation. This study expands our knowledge of the phylogeny and potential ecophysiology of the phylum Nitrospinota and offers new avenues for the isolation and cultivation of these elusive bacteria.
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Affiliation(s)
- Linnea F M Kop
- Department of Microbiology, Radboud Institute for Biological and Environmental Sciences, Radboud University, Heyendaalseweg 135, Nijmegen 6525 AJ, The Netherlands
- Division of Microbial Ecology, Centre for Microbiology and Environmental Systems Science, University of Vienna, Djerassiplatz 1, Vienna 1030, Austria
| | - Hanna Koch
- Department of Microbiology, Radboud Institute for Biological and Environmental Sciences, Radboud University, Heyendaalseweg 135, Nijmegen 6525 AJ, The Netherlands
- Bioresources Unit, Center for Health & Bioresources, AIT Austrian Institute of Technology GmbH, Konrad-Lorenz-Straße 24, Tulln an der Donau 3430, Austria
| | - Mike S M Jetten
- Department of Microbiology, Radboud Institute for Biological and Environmental Sciences, Radboud University, Heyendaalseweg 135, Nijmegen 6525 AJ, The Netherlands
| | - Holger Daims
- Division of Microbial Ecology, Centre for Microbiology and Environmental Systems Science, University of Vienna, Djerassiplatz 1, Vienna 1030, Austria
| | - Sebastian Lücker
- Department of Microbiology, Radboud Institute for Biological and Environmental Sciences, Radboud University, Heyendaalseweg 135, Nijmegen 6525 AJ, The Netherlands
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4
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Hoover RL, Keffer JL, Polson SW, Chan CS. Gallionellaceae pangenomic analysis reveals insight into phylogeny, metabolic flexibility, and iron oxidation mechanisms. mSystems 2023; 8:e0003823. [PMID: 37882557 PMCID: PMC10734462 DOI: 10.1128/msystems.00038-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Accepted: 09/20/2023] [Indexed: 10/27/2023] Open
Abstract
IMPORTANCE Neutrophilic iron-oxidizing bacteria (FeOB) produce copious iron (oxyhydr)oxides that can profoundly influence biogeochemical cycles, notably the fate of carbon and many metals. To fully understand environmental microbial iron oxidation, we need a thorough accounting of iron oxidation mechanisms. In this study, we show the Gallionellaceae FeOB genomes encode both characterized iron oxidases as well as uncharacterized multiheme cytochromes (MHCs). MHCs are predicted to transfer electrons from extracellular substrates and likely confer metabolic capabilities that help Gallionellaceae occupy a range of different iron- and mineral-rich niches. Gallionellaceae appear to specialize in iron oxidation, so it would be advantageous for them to have multiple mechanisms to oxidize various forms of iron, given the many iron minerals on Earth, as well as the physiological and kinetic challenges faced by FeOB. The multiple iron/mineral oxidation mechanisms may help drive the widespread ecological success of Gallionellaceae.
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Affiliation(s)
- Rene L. Hoover
- Microbiology Graduate Program, University of Delaware, Newark, Delaware, USA
- Department of Earth Sciences, University of Delaware, Newark, Delaware, USA
| | - Jessica L. Keffer
- Department of Earth Sciences, University of Delaware, Newark, Delaware, USA
| | - Shawn W. Polson
- Department of Computer and Information Sciences, University of Delaware, Newark, Delaware, USA
- Center for Bioinformatics and Computational Biology, University of Delaware, Newark, Delaware, USA
| | - Clara S. Chan
- Microbiology Graduate Program, University of Delaware, Newark, Delaware, USA
- Department of Earth Sciences, University of Delaware, Newark, Delaware, USA
- School of Marine Science and Policy, University of Delaware, Newark, Delaware, USA
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5
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Mehrani MJ, Kowal P, Sobotka D, Godzieba M, Ciesielski S, Guo J, Makinia J. The coexistence and competition of canonical and comammox nitrite oxidizing bacteria in a nitrifying activated sludge system - Experimental observations and simulation studies. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 864:161084. [PMID: 36565884 DOI: 10.1016/j.scitotenv.2022.161084] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2022] [Revised: 12/16/2022] [Accepted: 12/16/2022] [Indexed: 06/17/2023]
Abstract
The second step of nitrification can be mediated by nitrite oxidizing bacteria (NOB), i.e. Nitrospira and Nitrobacter, with different characteristics in terms of the r/K theory. In this study, an activated sludge model was developed to account for competition between two groups of canonical NOB and comammox bacteria. Heterotrophic denitrification on soluble microbial products was also incorporated into the model. Four 5-week washout trials were carried out at dissolved oxygen-limited conditions for different temperatures (12 °C vs. 20 °C) and main substrates (NH4+-N vs. NO2--N). Due to the aggressive reduction of solids retention time (from 4 to 1 d), the biomass concentrations were continuously decreased and stabilized after two weeks at a level below 400 mg/L. The collected experimental data (N species, biomass concentrations, and microbiological analyses) were used for model calibration and validation. In addition to the standard predictions (N species and biomass), the newly developed model also accurately predicted two microbiological indicators, including the relative abundance of comammox bacteria as well as nitrifiers to heterotrophs ratio. Sankey diagrams revealed that the relative contributions of specific microbial groups to N conversion pathways were significantly shifted during the trial. The contribution of comammox did not exceed 5 % in the experiments with both NH4+-N and NO2--N substrates. This study contributes to a better understanding of the novel autotrophic N removal processes (e.g. deammonification) with nitrite as a central intermediate product.
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Affiliation(s)
- Mohamad-Javad Mehrani
- Faculty of Civil and Environmental Engineering, Gdansk University of Technology, Narutowicza Street 11/12, 80-233 Gdansk, Poland
| | - Przemyslaw Kowal
- Faculty of Civil and Environmental Engineering, Gdansk University of Technology, Narutowicza Street 11/12, 80-233 Gdansk, Poland
| | - Dominika Sobotka
- Faculty of Civil and Environmental Engineering, Gdansk University of Technology, Narutowicza Street 11/12, 80-233 Gdansk, Poland
| | - Martyna Godzieba
- Department of Environmental Biotechnology, Department of Environmental Biotechnology, University of Warmia and Mazury in Olsztyn, Sloneczna 45G, 10-719 Olsztyn, Poland
| | - Slawomir Ciesielski
- Department of Environmental Biotechnology, Department of Environmental Biotechnology, University of Warmia and Mazury in Olsztyn, Sloneczna 45G, 10-719 Olsztyn, Poland
| | - Jianhua Guo
- Australian Centre for Water and Environmental Biotechnology (ACWEB, formerly AWMC), The University of Queensland, St. Lucia, Queensland 4072, Australia
| | - Jacek Makinia
- Faculty of Civil and Environmental Engineering, Gdansk University of Technology, Narutowicza Street 11/12, 80-233 Gdansk, Poland.
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6
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Hoover RL, Keffer JL, Polson SW, Chan CS. Gallionellaceae pangenomic analysis reveals insight into phylogeny, metabolic flexibility, and iron oxidation mechanisms. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.26.525709. [PMID: 36747706 PMCID: PMC9900912 DOI: 10.1101/2023.01.26.525709] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The iron-oxidizing Gallionellaceae drive a wide variety of biogeochemical cycles through their metabolisms and biominerals. To better understand the environmental impacts of Gallionellaceae, we need to improve our knowledge of their diversity and metabolisms, especially any novel iron oxidation mechanisms. Here, we used a pangenomic analysis of 103 genomes to resolve Gallionellaceae phylogeny and explore the range of genomic potential. Using a concatenated ribosomal protein tree and key gene patterns, we determined Gallionellaceae has four genera, divided into two groups-iron-oxidizing bacteria (FeOB) Gallionella, Sideroxydans, and Ferriphaselus with known iron oxidases (Cyc2, MtoA) and nitrite-oxidizing bacteria (NOB) Candidatus Nitrotoga with nitrite oxidase (Nxr). The FeOB and NOB have similar electron transport chains, including genes for reverse electron transport and carbon fixation. Auxiliary energy metabolisms including S oxidation, denitrification, and organotrophy were scattered throughout the Gallionellaceae FeOB. Within FeOB, we found genes that may represent adaptations for iron oxidation, including a variety of extracellular electron uptake (EEU) mechanisms. FeOB genomes encoded more predicted c-type cytochromes overall, notably more multiheme c-type cytochromes (MHCs) with >10 CXXCH motifs. These include homologs of several predicted outer membrane porin-MHC complexes, including MtoAB and Uet. MHCs are known to efficiently conduct electrons across longer distances and function across a wide range of redox potentials that overlap with mineral redox potentials, which can help expand the range of usable iron substrates. Overall, the results of pangenome analyses suggest that the Gallionellaceae genera Gallionella, Sideroxydans, and Ferriphaselus are primarily iron oxidizers, capable of oxidizing dissolved Fe2+ as well as a range of solid iron or other mineral substrates.
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Affiliation(s)
- Rene L. Hoover
- Microbiology Graduate Program, University of Delaware, Newark, Delaware, USA
- Department of Earth Sciences, University of Delaware, Newark, Delaware, USA
| | - Jessica L. Keffer
- Department of Earth Sciences, University of Delaware, Newark, Delaware, USA
| | - Shawn W. Polson
- Department of Computer and Information Sciences, University of Delaware, Newark, Delaware, USA
- Center for Bioinformatics and Computational Biology, University of Delaware, Newark, Delaware, USA
| | - Clara S. Chan
- Microbiology Graduate Program, University of Delaware, Newark, Delaware, USA
- Department of Earth Sciences, University of Delaware, Newark, Delaware, USA
- School of Marine Science and Policy, University of Delaware, Newark, Delaware, USA
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7
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Ide H, Ishii K, Takahashi Y, Fujitani H, Tsuneda S. Effects of Co-existing Heterotrophs on Physiology of and Nitrogen Metabolism in Autotrophic Nitrite-oxidizing Candidatus Nitrotoga. Microbes Environ 2023; 38:ME23076. [PMID: 38072409 PMCID: PMC10728634 DOI: 10.1264/jsme2.me23076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Accepted: 10/18/2023] [Indexed: 12/18/2023] Open
Abstract
Interactions between autotrophic nitrifiers and heterotrophs have attracted considerable attention in microbial ecology. However, the mechanisms by which heterotrophs affect the physiological activity of and nitrogen metabolism in autotrophic nitrite oxidizers remain unclear. We herein focused on nitrite-oxidizing Candidatus Nitrotoga and compared an axenic culture including only Ca. Nitrotoga with a co-culture of both Ca. Nitrotoga and Acidovorax in physiological experiments and transcriptomics. In the co-culture with Acidovorax, nitrite consumption by Ca. Nitrotoga was promoted, and some genes relevant to nitrogen metabolism in Ca. Nitrotoga were highly expressed. These results provide insights into the mechanisms by which co-existing heterotrophs affect autotrophic nitrifiers.
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Affiliation(s)
- Hiroto Ide
- Department of Life Science and Medical Bioscience, Waseda University, Tokyo, Japan
| | - Kento Ishii
- Department of Life Science and Medical Bioscience, Waseda University, Tokyo, Japan
- Research Organization for Nano & Life Innovation, Waseda University, Tokyo, Japan
| | - Yu Takahashi
- Department of Life Science and Medical Bioscience, Waseda University, Tokyo, Japan
| | - Hirotsugu Fujitani
- Research Organization for Nano & Life Innovation, Waseda University, Tokyo, Japan
- Department of Biological Sciences, Chuo University, Tokyo, Japan
| | - Satoshi Tsuneda
- Department of Life Science and Medical Bioscience, Waseda University, Tokyo, Japan
- Research Organization for Nano & Life Innovation, Waseda University, Tokyo, Japan
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8
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Kowal P, Mehrani MJ, Sobotka D, Ciesielski S, Mąkinia J. Rearrangements of the nitrifiers population in an activated sludge system under decreasing solids retention times. ENVIRONMENTAL RESEARCH 2022; 214:113753. [PMID: 35772505 DOI: 10.1016/j.envres.2022.113753] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Revised: 06/17/2022] [Accepted: 06/20/2022] [Indexed: 06/15/2023]
Abstract
Due to the key role of nitrite in novel nitrogen removal systems, nitrite oxidizing bacteria (NOB) have been receiving increasing attention. In this study, the coexistence and interactions of nitrifying bacteria were explored at decreasing solids retention times (SRTs). Four 5-week washout experiments were carried out in laboratory-scale (V = 10 L) sequencing batch reactors (SBRs) with mixed liquor from two full-scale activated sludge systems (continuous flow vs SBR). During the experiments, the SRT was gradually reduced from the initial value of 4.0 d to approximately 1.0 d. The reactors were operated under limited dissolved oxygen conditions (set point of 0.6 mg O2/L) and two process temperatures: 12 °C (winter) and 20 °C (summer). At both temperatures, the progressive SRT reduction was inefficient for the out-selection of both canonical NOB and comammox Nitrospira. However, the dominant NOB switched from Nitrospira to Ca. Nitrotoga, whereas the dominant AOB was always Nitrosomonas. The results of this study are important for optimizing NOB suppression strategies in the novel N removal processes, which are based on nitrite accumulation.
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Affiliation(s)
- Przemyslaw Kowal
- Faculty of Civil and Environmental Engineering, Gdansk University of Technology, Narutowicza Street 11/12, 80-233, Gdansk, Poland.
| | - Mohamad-Javad Mehrani
- Faculty of Civil and Environmental Engineering, Gdansk University of Technology, Narutowicza Street 11/12, 80-233, Gdansk, Poland
| | - Dominika Sobotka
- Faculty of Civil and Environmental Engineering, Gdansk University of Technology, Narutowicza Street 11/12, 80-233, Gdansk, Poland
| | - Sławomir Ciesielski
- Department of Environmental Biotechnology, Faculty of Geoengineering, University of Warmia and Mazury in Olsztyn, Ul. Sloneczna 45G, 10-709, Olsztyn, Poland
| | - Jacek Mąkinia
- Faculty of Civil and Environmental Engineering, Gdansk University of Technology, Narutowicza Street 11/12, 80-233, Gdansk, Poland
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Barbato M, Vacchini V, Engelen AH, Patania G, Mapelli F, Borin S, Crotti E. What lies on macroalgal surface: diversity of polysaccharide degraders in culturable epiphytic bacteria. AMB Express 2022; 12:98. [PMID: 35895126 PMCID: PMC9329506 DOI: 10.1186/s13568-022-01440-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Accepted: 07/13/2022] [Indexed: 11/10/2022] Open
Abstract
Macroalgal surface constitutes a peculiar ecological niche and an advantageous substratum for microorganisms able to degrade the wide diversity of algal glycans. The degrading enzymatic activities of macroalgal epiphytes are of paramount interest for the industrial by-product sector and biomass resource applications. We characterized the polysaccharide hydrolytic profile of bacterial isolates obtained from three macroalgal species: the red macroalgae Asparagopsis taxiformis and Sphaerococcus coronopifolius (Rhodophyceae) and the brown Halopteris scoparia (Phaeophyceae), sampled in South Portugal. Bacterial enrichment cultures supplemented with chlorinated aliphatic compounds, typically released by marine algae, were established using as inoculum the decaying biomass of the three macroalgae, obtaining a collection of 634 bacterial strains. Although collected from the same site and exposed to the same seawater seeding microbiota, macroalgal cultivable bacterial communities in terms of functional and phylogenetic diversity showed host specificity. Isolates were tested for the hydrolysis of starch, pectin, alginate and agar, exhibiting a different hydrolytic potential according to their host: A. taxiformis showed the highest percentage of active isolates (91%), followed by S. coronopifolius (54%) and H. scoparia (46%). Only 30% of the isolates were able to degrade starch, while the other polymers were degraded by 55-58% of the isolates. Interestingly, several isolates showed promiscuous capacities to hydrolyze more than one polysaccharide. The isolate functional fingerprint was statistically correlated to bacterial phylogeny, host species and enrichment medium. In conclusion, this work depicts macroalgae as holobionts with an associated microbiota of interest for blue biotechnologies, suggesting isolation strategies and bacterial targets for polysaccharidases' discovery.
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Affiliation(s)
- Marta Barbato
- Dipartimento di Scienze per gli Alimenti, la Nutrizione e l'Ambiente (DeFENS), Università degli Studi di Milano, via Celoria 2, 20133, Milano, Italy.,Department of Biology, Section for Microbiology, Aarhus University, Ny Munkegade 116, 8000, Aarhus, Denmark
| | - Violetta Vacchini
- Dipartimento di Scienze per gli Alimenti, la Nutrizione e l'Ambiente (DeFENS), Università degli Studi di Milano, via Celoria 2, 20133, Milano, Italy
| | - Aschwin H Engelen
- Centro de Ciências do Mar (CCMAR), Universidade do Algarve, Campus de Gambelas, 8005-139, Faro, Portugal
| | - Giovanni Patania
- Dipartimento di Scienze per gli Alimenti, la Nutrizione e l'Ambiente (DeFENS), Università degli Studi di Milano, via Celoria 2, 20133, Milano, Italy
| | - Francesca Mapelli
- Dipartimento di Scienze per gli Alimenti, la Nutrizione e l'Ambiente (DeFENS), Università degli Studi di Milano, via Celoria 2, 20133, Milano, Italy
| | - Sara Borin
- Dipartimento di Scienze per gli Alimenti, la Nutrizione e l'Ambiente (DeFENS), Università degli Studi di Milano, via Celoria 2, 20133, Milano, Italy.
| | - Elena Crotti
- Dipartimento di Scienze per gli Alimenti, la Nutrizione e l'Ambiente (DeFENS), Università degli Studi di Milano, via Celoria 2, 20133, Milano, Italy
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10
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Cydzik-Kwiatkowska A, de Jonge N, Poulsen JS, Nielsen JL. Unravelling gradient layers of microbial communities, proteins, and chemical structure in aerobic granules. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 829:154253. [PMID: 35276168 DOI: 10.1016/j.scitotenv.2022.154253] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Revised: 02/26/2022] [Accepted: 02/26/2022] [Indexed: 06/14/2023]
Abstract
Most bacteria live in microbial assemblages like biofilms and granules, and each layer of these assemblages provides a niche for certain bacteria with specific metabolic functions. In this study, a gentle (non-destructive) extraction approach based on a cation exchange resin and defined shear was employed to gradually disintegrate biomass and collect single layers of aerobic granules from a full-scale municipal wastewater treatment plant. The microbial community composition of granule layers was characterized using next-generation sequencing (NGS) targeting the 16S rRNA gene, and protein composition was investigated using metaproteomics. The chemical composition of eroded layers was explored using Fourier Transformed Infrared Spectroscopy. On the surface of the granules, the microbial structure (flocculation-supporting Nannocystis sp.) as well as composition of extracellular polymers (extracellular DNA) and proteome (chaperonins and binding proteins) favored microbial aggregation. Extracellular polymeric substances in the granules were composed of mostly proteins and EPS-producers, such as Tetrasphaera sp. and Zoogloea sp., were evenly distributed throughout the granule structure. The interior of the granules harbored several denitrifiers (e.g., Thauera sp.), phosphate-accumulating denitrifiers (Candidatus Accumulibacter, Dechloromonas sp.) and nitrifiers (Candidatus Nitrotoga). Proteins associated with glycolytic activity were identified in the outer and middle granule layers, and proteins associated with phosphorus conversions, in the deeper layers. In conclusion, the use of an existing cation-exchange resin for gradual biomass disintegration, combined with NGS and metaproteomic analysis was demonstrated as a promising approach for simultaneously investigating the identity and functions of microbes in multilayered biofilm structures.
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Affiliation(s)
- Agnieszka Cydzik-Kwiatkowska
- University of Warmia and Mazury in Olsztyn, Faculty of Geoengineering, Department of Environmental Biotechnology, Sloneczna 45G, Olsztyn, Poland
| | - Nadieh de Jonge
- Aalborg University, Department of Chemistry and Bioscience, Fredrik Bajers Vej 7H, 9220 Aalborg, Denmark
| | - Jan Struckmann Poulsen
- Aalborg University, Department of Chemistry and Bioscience, Fredrik Bajers Vej 7H, 9220 Aalborg, Denmark
| | - Jeppe Lund Nielsen
- Aalborg University, Department of Chemistry and Bioscience, Fredrik Bajers Vej 7H, 9220 Aalborg, Denmark.
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11
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Elling FJ, Evans TW, Nathan V, Hemingway JD, Kharbush JJ, Bayer B, Spieck E, Husain F, Summons RE, Pearson A. Marine and terrestrial nitrifying bacteria are sources of diverse bacteriohopanepolyols. GEOBIOLOGY 2022; 20:399-420. [PMID: 35060273 DOI: 10.1111/gbi.12484] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2021] [Accepted: 12/31/2021] [Indexed: 06/14/2023]
Abstract
Hopanoid lipids, bacteriohopanols and bacteriohopanepolyols, are membrane components exclusive to bacteria. Together with their diagenetic derivatives, they are commonly used as biomarkers for specific bacterial groups or biogeochemical processes in the geologic record. However, the sources of hopanoids to marine and freshwater environments remain inadequately constrained. Recent marker gene studies suggest a widespread potential for hopanoid biosynthesis in marine bacterioplankton, including nitrifying (i.e., ammonia- and nitrite-oxidizing) bacteria. To explore their hopanoid biosynthetic capacities, we studied the distribution of hopanoid biosynthetic genes in the genomes of cultivated and uncultivated ammonia-oxidizing (AOB), nitrite-oxidizing (NOB), and complete ammonia-oxidizing (comammox) bacteria, finding that biosynthesis of diverse hopanoids is common among seven of the nine presently cultivated clades of nitrifying bacteria. Hopanoid biosynthesis genes are also conserved among the diverse lineages of bacterial nitrifiers detected in environmental metagenomes. We selected seven representative NOB isolated from marine, freshwater, and engineered environments for phenotypic characterization. All tested NOB produced diverse types of hopanoids, with some NOB producing primarily diploptene and others producing primarily bacteriohopanepolyols. Relative and absolute abundances of hopanoids were distinct among the cultures and dependent on growth conditions, such as oxygen and nitrite limitation. Several novel nitrogen-containing bacteriohopanepolyols were tentatively identified, of which the so called BHP-743.6 was present in all NOB. Distinct carbon isotopic signatures of biomass, hopanoids, and fatty acids in four tested NOB suggest operation of the reverse tricarboxylic acid cycle in Nitrospira spp. and Nitrospina gracilis and of the Calvin-Benson-Bassham cycle for carbon fixation in Nitrobacter vulgaris and Nitrococcus mobilis. We suggest that the contribution of hopanoids by NOB to environmental samples could be estimated by their carbon isotopic compositions. The ubiquity of nitrifying bacteria in the ocean today and the antiquity of this metabolic process suggest the potential for significant contributions to the geologic record of hopanoids.
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Affiliation(s)
- Felix J Elling
- Department of Earth and Planetary Sciences, Harvard University, Cambridge, Massachusetts, USA
| | - Thomas W Evans
- Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Vinitra Nathan
- Department of Earth and Planetary Sciences, Harvard University, Cambridge, Massachusetts, USA
| | - Jordon D Hemingway
- Department of Earth and Planetary Sciences, Harvard University, Cambridge, Massachusetts, USA
| | - Jenan J Kharbush
- Department of Earth and Planetary Sciences, Harvard University, Cambridge, Massachusetts, USA
- Department of Earth and Environmental Science, University of Michigan, Ann Arbor, Michigan, USA
| | - Barbara Bayer
- Department of Ecology, Evolution and Marine Biology, University of California, Santa Barbara, California, USA
| | - Eva Spieck
- Department of Microbiology and Biotechnology, University of Hamburg, Hamburg, Germany
| | - Fatima Husain
- Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Roger E Summons
- Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Ann Pearson
- Department of Earth and Planetary Sciences, Harvard University, Cambridge, Massachusetts, USA
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12
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Genome Streamlining, Proteorhodopsin, and Organic Nitrogen Metabolism in Freshwater Nitrifiers. mBio 2022; 13:e0237921. [PMID: 35435701 PMCID: PMC9239080 DOI: 10.1128/mbio.02379-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
Microbial nitrification is a critical process governing nitrogen availability in aquatic systems. Freshwater nitrifiers have received little attention, leaving many unanswered questions about their taxonomic distribution, functional potential, and ecological interactions. Here, we reconstructed genomes to infer the metabolism and ecology of free-living picoplanktonic nitrifiers across the Laurentian Great Lakes, a connected series of five of Earth’s largest lakes. Surprisingly, ammonia-oxidizing bacteria (AOB) related to Nitrosospira dominated over ammonia-oxidizing archaea (AOA) at nearly all stations, with distinct ecotypes prevailing in the transparent, oligotrophic upper lakes compared to Lakes Erie and Ontario. Unexpectedly, one ecotype of Nitrosospira encodes proteorhodopsin, which could enhance survival under conditions where ammonia oxidation is inhibited or substrate limited. Nitrite-oxidizing bacteria (NOB) “Candidatus Nitrotoga” and Nitrospira fluctuated in dominance, with the latter prevailing in deeper, less-productive basins. Genome reconstructions reveal highly reduced genomes and features consistent with genome streamlining, along with diverse adaptations to sunlight and oxidative stress and widespread capacity for organic nitrogen use. Our findings expand the known functional diversity of nitrifiers and establish their ecological genomics in large lake ecosystems. By elucidating links between microbial biodiversity and biogeochemical cycling, our work also informs ecosystem models of the Laurentian Great Lakes, a critical freshwater resource experiencing rapid environmental change.
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13
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Keuter S, Koch H, Sass K, Wegen S, Lee N, Lücker S, Spieck E. Some like it cold: The cellular organization and physiological limits of cold-tolerant nitrite-oxidizing Nitrotoga. Environ Microbiol 2022; 24:2059-2077. [PMID: 35229435 DOI: 10.1111/1462-2920.15958] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Revised: 02/18/2022] [Accepted: 02/24/2022] [Indexed: 11/30/2022]
Abstract
Chemolithoautotrophic production of nitrate is accomplished by the polyphyletic functional group of nitrite-oxidizing bacteria (NOB). A widely distributed and important NOB clade in nitrogen removal processes at low temperatures is Nitrotoga, which however remains understudied due to the scarcity of cultivated representatives. Here, we present physiological, ultrastructural and genomic features of Nitrotoga strains from various habitats, including the first marine species enriched from an aquaculture system. Immunocytochemical analyses localized the nitrite-oxidizing enzyme machinery in the wide irregularly shaped periplasm, apparently without contact to the cytoplasmic membrane, confirming previous genomic data suggesting a soluble nature. Interestingly, in two strains we also observed multicellular complexes with a shared periplasmic space, which seem to form through incomplete cell division and might enhance fitness or survival. Physiological tests revealed differing tolerance limits towards dissolved inorganic nitrogen concentrations and confirmed the generally psychrotolerant nature of the genus was. Moreover, comparative analysis of 15 Nitrotoga genomes showed, e.g., a unique gene repertoire of the marine strain that could be advantageous in its natural habitat and confirmed the lack of genes for assimilatory nitrite reduction in a strain found to require ammonium for growth. Overall, these novel insights largely broaden our knowledge of Nitrotoga and elucidate the metabolic variability, physiological limits and thus potential ecological roles of this group of nitrite oxidizers. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Sabine Keuter
- Department of Microbiology and Biotechnology, University of Hamburg, Hamburg, Germany
| | - Hanna Koch
- Department of Microbiology, RIBES, Radboud University, Nijmegen, the Netherlands
| | - Katharina Sass
- Department of Microbiology and Biotechnology, University of Hamburg, Hamburg, Germany
| | - Simone Wegen
- Department of Microbiology and Biotechnology, University of Hamburg, Hamburg, Germany
| | - Natuschka Lee
- Department of Ecology and Environmental Science and Research Infrastructure Fluorescence in situ Hybridization (FISH), Chemical Biological Centre, Umeå University, Umeå, Sweden.,Department of Microbiology, Technical University of Munich, Freising, Germany
| | - Sebastian Lücker
- Department of Microbiology, RIBES, Radboud University, Nijmegen, the Netherlands
| | - Eva Spieck
- Department of Microbiology and Biotechnology, University of Hamburg, Hamburg, Germany
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14
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The marine nitrogen cycle: new developments and global change. Nat Rev Microbiol 2022; 20:401-414. [PMID: 35132241 DOI: 10.1038/s41579-022-00687-z] [Citation(s) in RCA: 51] [Impact Index Per Article: 25.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/07/2022] [Indexed: 12/25/2022]
Abstract
The ocean is home to a diverse and metabolically versatile microbial community that performs the complex biochemical transformations that drive the nitrogen cycle, including nitrogen fixation, assimilation, nitrification and nitrogen loss processes. In this Review, we discuss the wealth of new ocean nitrogen cycle research in disciplines from metaproteomics to global biogeochemical modelling and in environments from productive estuaries to the abyssal deep sea. Influential recent discoveries include new microbial functional groups, novel metabolic pathways, original conceptual perspectives and ground-breaking analytical capabilities. These emerging research directions are already contributing to urgent efforts to address the primary challenge facing marine microbiologists today: the unprecedented onslaught of anthropogenic environmental change on marine ecosystems. Ocean warming, acidification, nutrient enrichment and seawater stratification have major effects on the microbial nitrogen cycle, but widespread ocean deoxygenation is perhaps the most consequential for the microorganisms involved in both aerobic and anaerobic nitrogen transformation pathways. In turn, these changes feed back to the global cycles of greenhouse gases such as carbon dioxide and nitrous oxide. At a time when our species casts a lengthening shadow across all marine ecosystems, timely new advances offer us unique opportunities to understand and better predict human impacts on nitrogen biogeochemistry in the changing ocean of the Anthropocene.
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15
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Ruen-Pham K, Graham LE, Satjarak A. Spatial Variation of Cladophora Epiphytes in the Nan River, Thailand. PLANTS (BASEL, SWITZERLAND) 2021; 10:2266. [PMID: 34834629 PMCID: PMC8622721 DOI: 10.3390/plants10112266] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Revised: 10/19/2021] [Accepted: 10/20/2021] [Indexed: 11/16/2022]
Abstract
Cladophora is an algal genus known to be ecologically important. It provides habitats for microorganisms known to provide ecological services such as biosynthesis of cobalamin (vitamin B12) and nutrient cycling. Most knowledge of microbiomes was obtained from studies of lacustrine Cladophora species. However, whether lotic freshwater Cladophora microbiomes are as complex as the lentic ones or provide similar ecological services is not known. To illuminate these issues, we used amplicons of 16S rDNA, 18S rDNA, and ITS to investigate the taxonomy and diversity of the microorganisms associated with replicate Cladophora samples from three sites along the Nan River, Thailand. Results showed that the diversity of prokaryotic and eukaryotic members of Cladophora microbiomes collected from different sampling sites was statistically different. Fifty percent of the identifiable taxa were shared across sampling sites: these included organisms belonging to different trophic levels, decomposers, and heterotrophic bacteria. These heterogeneous assemblages of bacteria, by functional inference, have the potential to perform various ecological functions, i.e., cellulose degradation, cobalamin biosynthesis, fermentative hydrogen production, ammonium oxidation, amino acid fermentation, dissimilatory reduction of nitrate to ammonium, nitrite reduction, nitrate reduction, sulfur reduction, polyphosphate accumulation, denitrifying phosphorus-accumulation, and degradation of aromatic compounds. Results suggested that river populations of Cladophora provide ecologically important habitat for microorganisms that are key to nutrient cycling in lotic ecosystems.
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Affiliation(s)
- Karnjana Ruen-Pham
- Plants of Thailand Research Unit, Department of Botany, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand;
| | - Linda E. Graham
- Department of Botany, University of Wisconsin-Madison, 430 Lincoln Drive, Madison, WI 53706, USA;
| | - Anchittha Satjarak
- Plants of Thailand Research Unit, Department of Botany, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand;
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16
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Spieck E, Wegen S, Keuter S. Relevance of Candidatus Nitrotoga for nitrite oxidation in technical nitrogen removal systems. Appl Microbiol Biotechnol 2021; 105:7123-7139. [PMID: 34508283 PMCID: PMC8494671 DOI: 10.1007/s00253-021-11487-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Revised: 07/29/2021] [Accepted: 07/31/2021] [Indexed: 01/10/2023]
Abstract
Abstract Many biotechnological applications deal with nitrification, one of the main steps of the global nitrogen cycle. The biological oxidation of ammonia to nitrite and further to nitrate is critical to avoid environmental damage and its functioning has to be retained even under adverse conditions. Bacteria performing the second reaction, oxidation of nitrite to nitrate, are fastidious microorganisms that are highly sensitive against disturbances. One important finding with relevance for nitrogen removal systems was the discovery of the mainly cold-adapted Cand. Nitrotoga, whose activity seems to be essential for the recovery of nitrite oxidation in wastewater treatment plants at low temperatures, e.g., during cold seasons. Several new strains of this genus have been recently described and ecophysiologically characterized including genome analyses. With increasing diversity, also mesophilic Cand. Nitrotoga representatives have been detected in activated sludge. This review summarizes the natural distribution and driving forces defining niche separation in artificial nitrification systems. Further critical aspects for the competition with Nitrospira and Nitrobacter are discussed. Knowledge about the physiological capacities and limits of Cand. Nitrotoga can help to define physico-chemical parameters for example in reactor systems that need to be run at low temperatures. Key points • Characterization of the psychrotolerant nitrite oxidizer Cand. Nitrotoga • Comparison of the physiological features of Cand. Nitrotoga with those of other NOB • Identification of beneficial environmental/operational parameters for proliferation Supplementary Information The online version contains supplementary material available at 10.1007/s00253-021-11487-5.
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Affiliation(s)
- Eva Spieck
- Department of Microbiology and Biotechnology, Universität Hamburg, Hamburg, Germany.
| | - Simone Wegen
- Department of Microbiology and Biotechnology, Universität Hamburg, Hamburg, Germany
| | - Sabine Keuter
- Department of Microbiology and Biotechnology, Universität Hamburg, Hamburg, Germany
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17
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Lantz MA, Boddicker AM, Kain MP, Berg OMC, Wham CD, Mosier AC. Physiology of the Nitrite-Oxidizing Bacterium Candidatus Nitrotoga sp. CP45 Enriched From a Colorado River. Front Microbiol 2021; 12:709371. [PMID: 34484146 PMCID: PMC8415719 DOI: 10.3389/fmicb.2021.709371] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Accepted: 07/19/2021] [Indexed: 11/13/2022] Open
Abstract
Nitrogen cycling microbes, including nitrite-oxidizing bacteria (NOB), perform critical ecosystem functions that help mitigate anthropogenic stresses and maintain ecosystem health. Activity of these beneficial nitrogen cycling microbes is dictated in part by the microorganisms’ response to physicochemical conditions, such as temperature, pH, and nutrient availability. NOB from the newly described Candidatus Nitrotoga genus have been detected in a wide range of habitats across the globe, yet only a few organisms within the genus have been physiologically characterized. For freshwater systems where NOB are critical for supporting aquatic life, Ca. Nitrotoga have been previously detected but little is known about the physiological potential of these organisms or their response to changing environmental conditions. Here, we determined functional response to environmental change for a representative freshwater species of Ca. Nitrotoga (Ca. Nitrotoga sp. CP45, enriched from a Colorado river). The physiological findings demonstrated that CP45 maintained nitrite oxidation at pH levels of 5–8, at temperatures from 4 to 28°C, and when incubated in the dark. Light exposure and elevated temperature (30°C) completely halted nitrite oxidation. Ca. Nitrotoga sp. CP45 maintained nitrite oxidation upon exposure to four different antibiotics, and potential rates of nitrite oxidation by river sediment communities were also resilient to antibiotic stress. We explored the Ca. Nitrotoga sp. CP45 genome to make predictions about adaptations to enable survival under specific conditions. Overall, these results contribute to our understanding of the versatility of a representative freshwater Ca. Nitrotoga sp. Identifying the specific environmental conditions that maximize NOB metabolic rates may ultimately direct future management decisions aimed at restoring impacted systems.
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Affiliation(s)
- Munira A Lantz
- Department of Integrative Biology, University of Colorado Denver, Denver, CO, United States
| | - Andrew M Boddicker
- Department of Integrative Biology, University of Colorado Denver, Denver, CO, United States
| | - Michael P Kain
- Department of Integrative Biology, University of Colorado Denver, Denver, CO, United States
| | - Owen M C Berg
- Department of Integrative Biology, University of Colorado Denver, Denver, CO, United States
| | - Courtney D Wham
- Department of Integrative Biology, University of Colorado Denver, Denver, CO, United States
| | - Annika C Mosier
- Department of Integrative Biology, University of Colorado Denver, Denver, CO, United States
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18
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Fujitani H, Momiuchi K, Ishii K, Nomachi M, Kikuchi S, Ushiki N, Sekiguchi Y, Tsuneda S. Genomic and Physiological Characteristics of a Novel Nitrite-Oxidizing Nitrospira Strain Isolated From a Drinking Water Treatment Plant. Front Microbiol 2020; 11:545190. [PMID: 33042056 PMCID: PMC7522533 DOI: 10.3389/fmicb.2020.545190] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Accepted: 08/24/2020] [Indexed: 11/13/2022] Open
Abstract
Nitrite-oxidizing bacteria (NOB) catalyze the second step of nitrification, which is an important process of the biogeochemical nitrogen cycle and is exploited extensively as a biological nitrogen removal process. Members of the genus Nitrospira are often identified as the dominant NOB in a diverse range of natural and artificial environments. Additionally, a number of studies examining the distribution, abundance, and characterization of complete ammonia oxidation (comammox) Nitrospira support the ecological importance of the genus Nitrospira. However, niche differentiation between nitrite-oxidizing Nitrospira and comammox Nitrospira remains unknown due to a lack of pure cultures. In this study, we report the isolation, physiology, and genome of a novel nitrite-oxidizing Nitrospira strain isolated from a fixed-bed column at a drinking water treatment plant. Continuous feeding of ammonia led to the enrichment of Nitrospira-like cells, as well as members of ammonia-oxidizing genus Nitrosomonas. Subsequently, a microcolony sorting technique was used to isolate a novel nitrite-oxidizing Nitrospira strain. Sequences of strains showing the growth of microcolonies in microtiter plates were checked. Consequently, the most abundant operational taxonomic unit (OTU) exhibited high sequence similarity with Nitrospira japonica (98%) at the 16S rRNA gene level. The two other Nitrospira OTUs shared over 99% sequence similarities with N. japonica and Nitrospira sp. strain GC86. Only one strain identified as Nitrospira was successfully subcultivated and designated as Nitrospira sp. strain KM1 with high sequence similarity with N. japonica (98%). The half saturation constant for nitrite and the maximum nitrite oxidation rate of strain KM1 were orders of magnitude lower than the published data of other known Nitrospira strains; moreover, strain KM1 was more sensitive to free ammonia compared with previously isolated Nitrospira strains. Therefore, the new Nitrospira strain appears to be better adapted to oligotrophic environments compared with other known non-marine nitrite oxidizers. The complete genome of strain KM1 was 4,509,223 bp in length and contained 4,318 predicted coding sequences. Average nucleotide identities between strain KM1 and known cultured Nitrospira genome sequences are 76.7-78.4%, suggesting at least species-level novelty of the strain in the Nitrospira lineage II. These findings broaden knowledge of the ecophysiological diversity of nitrite-oxidizing Nitrospira.
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Affiliation(s)
- Hirotsugu Fujitani
- Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology, Tsukuba, Japan.,Research Organization for Nano & Life Innovation, Waseda University, Tokyo, Japan
| | - Kengo Momiuchi
- Department of Life Science and Medical Bioscience, Waseda University, Tokyo, Japan
| | - Kento Ishii
- Department of Life Science and Medical Bioscience, Waseda University, Tokyo, Japan
| | - Manami Nomachi
- Department of Life Science and Medical Bioscience, Waseda University, Tokyo, Japan
| | - Shuta Kikuchi
- Department of Life Science and Medical Bioscience, Waseda University, Tokyo, Japan
| | - Norisuke Ushiki
- Department of Life Science and Medical Bioscience, Waseda University, Tokyo, Japan
| | - Yuji Sekiguchi
- Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology, Tsukuba, Japan
| | - Satoshi Tsuneda
- Research Organization for Nano & Life Innovation, Waseda University, Tokyo, Japan.,Department of Life Science and Medical Bioscience, Waseda University, Tokyo, Japan
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