Dataset Information

Ultrastructure and Viral Metagenome of Bacteriophages from an Anaerobic Methane Oxidizing Methylomirabilis Bioreactor Enrichment Culture.

ABSTRACT: With its capacity for anaerobic methane oxidation and denitrification, the bacterium Methylomirabilis oxyfera plays an important role in natural ecosystems. Its unique physiology can be exploited for more sustainable wastewater treatment technologies. However, operational stability of full-scale bioreactors can experience setbacks due to, for example, bacteriophage blooms. By shaping microbial communities through mortality, horizontal gene transfer, and metabolic reprogramming, bacteriophages are important players in most ecosystems. Here, we analyzed an infected Methylomirabilis sp. bioreactor enrichment culture using (advanced) electron microscopy, viral metagenomics and bioinformatics. Electron micrographs revealed four different viral morphotypes, one of which was observed to infect Methylomirabilis cells. The infected cells contained densely packed ~55 nm icosahedral bacteriophage particles with a putative internal membrane. Various stages of virion assembly were observed. Moreover, during the bacteriophage replication, the host cytoplasmic membrane appeared extremely patchy, which suggests that the bacteriophages may use host bacterial lipids to build their own putative internal membrane. The viral metagenome contained 1.87 million base pairs of assembled viral sequences, from which five putative complete viral genomes were assembled and manually annotated. Using bioinformatics analyses, we could not identify which viral genome belonged to the Methylomirabilis- infecting bacteriophage, in part because the obtained viral genome sequences were novel and unique to this reactor system. Taken together these results show that new bacteriophages can be detected in anaerobic cultivation systems and that the effect of bacteriophages on the microbial community in these systems is a topic for further study.

SUBMITTER: Gambelli L

PROVIDER: S-EPMC5099504 | biostudies-literature | 2016

REPOSITORIES: biostudies-literature

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Ultrastructure and Viral Metagenome of Bacteriophages from an Anaerobic Methane Oxidizing <i>Methylomirabilis</i> Bioreactor Enrichment Culture.

Gambelli Lavinia L Cremers Geert G Mesman Rob R Guerrero Simon S Dutilh Bas E BE Jetten Mike S M MS Op den Camp Huub J M HJ van Niftrik Laura L

Frontiers in microbiology 20161108

With its capacity for anaerobic methane oxidation and denitrification, the bacterium <i>Methylomirabilis oxyfera</i> plays an important role in natural ecosystems. Its unique physiology can be exploited for more sustainable wastewater treatment technologies. However, operational stability of full-scale bioreactors can experience setbacks due to, for example, bacteriophage blooms. By shaping microbial communities through mortality, horizontal gene transfer, and metabolic reprogramming, bacterioph ...[more]

PMID: 27877158

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Project description:Methane is a very potent greenhouse gas and can be oxidized aerobically or anaerobically through microbe-mediated processes, thus decreasing methane emissions in the atmosphere. Using a complementary array of methods, including phylogenetic analysis, physiological experiments, and light and electron microscopy techniques (including electron tomography), we investigated the community composition and ultrastructure of a continuous bioreactor enrichment culture, in which anaerobic oxidation of methane (AOM) was coupled to nitrate reduction. A membrane bioreactor was seeded with AOM biomass and continuously fed with excess methane. After 150 days, the bioreactor reached a daily consumption of 10 mmol nitrate · liter-1 · day-1 The biomass consisted of aggregates that were dominated by nitrate-dependent anaerobic methane-oxidizing "Candidatus Methanoperedens"-like archaea (40%) and nitrite-dependent anaerobic methane-oxidizing "Candidatus Methylomirabilis"-like bacteria (50%). The "Ca Methanoperedens" spp. were identified by fluorescence in situ hybridization and immunogold localization of the methyl-coenzyme M reductase (Mcr) enzyme, which was located in the cytoplasm. The "Ca Methanoperedens" sp. aggregates consisted of slightly irregular coccoid cells (∼1.5-μm diameter) which produced extruding tubular structures and putative cell-to-cell contacts among each other. "Ca Methylomirabilis" sp. bacteria exhibited the polygonal cell shape typical of this genus. In AOM archaea and bacteria, cytochrome c proteins were localized in the cytoplasm and periplasm, respectively, by cytochrome staining. Our results indicate that AOM bacteria and archaea might work closely together in the process of anaerobic methane oxidation, as the bacteria depend on the archaea for nitrite. Future studies will be aimed at elucidating the function of the cell-to-cell interactions in nitrate-dependent AOM.IMPORTANCE Microorganisms performing nitrate- and nitrite-dependent anaerobic methane oxidation are important in both natural and man-made ecosystems, such as wastewater treatment plants. In both systems, complex microbial interactions take place that are largely unknown. Revealing these microbial interactions would enable us to understand how the oxidation of the important greenhouse gas methane occurs in nature and pave the way for the application of these microbes in wastewater treatment plants. Here, we elucidated the microbial composition, ultrastructure, and physiology of a nitrate-dependent AOM community of archaea and bacteria and describe the cell plan of "Ca Methanoperedens"-like methanotrophic archaea.

Dataset Information

Ultrastructure and Viral Metagenome of Bacteriophages from an Anaerobic Methane Oxidizing Methylomirabilis Bioreactor Enrichment Culture.

Publications

Ultrastructure and Viral Metagenome of Bacteriophages from an Anaerobic Methane Oxidizing <i>Methylomirabilis</i> Bioreactor Enrichment Culture.

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