title: Ultrastructure and Viral Metagenome of Bacteriophages from an Anaerobic Methane OxidizingMethylomirabilisBioreactor Enrichment Culture.
abstract: With its capacity for anaerobic methane oxidation and denitrification, the bacteriumMethylomirabilis oxyferaplays 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 infectedMethylomirabilissp. bioreactor enrichment culture using (advanced) electron microscopy, viral metagenomics and bioinformatics. Electron micrographs revealed four different viral morphotypes, one of which was observed to infectMethylomirabiliscells. 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 theMethylomirabilis- 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.
authors.affiliation: Department of Microbiology, Faculty of Science, Institute for Water and Wetland Research, Radboud University Nijmegen, Netherlands.
authors.forename: Lavinia
authors.initials: L
authors.lastname: Gambelli
authors.affiliation: Department of Microbiology, Faculty of Science, Institute for Water and Wetland Research, Radboud University Nijmegen, Netherlands.
authors.forename: Geert
authors.initials: G
authors.lastname: Cremers
authors.affiliation: Department of Microbiology, Faculty of Science, Institute for Water and Wetland Research, Radboud University Nijmegen, Netherlands.
authors.forename: Rob
authors.initials: R
authors.lastname: Mesman
authors.affiliation: Department of Microbiology, Faculty of Science, Institute for Water and Wetland Research, Radboud University Nijmegen, Netherlands.
authors.forename: Simon
authors.initials: S
authors.lastname: Guerrero
authors.affiliation: Theoretical Biology and Bioinformatics, Utrecht UniversityUtrecht, Netherlands; Centre for Molecular and Biomolecular Informatics, Radboud University Medical CentreNijmegen, Netherlands.
authors.forename: Bas E
authors.initials: BE
authors.lastname: Dutilh
authors.affiliation: Department of Microbiology, Faculty of Science, Institute for Water and Wetland Research, Radboud University Nijmegen, Netherlands.
authors.forename: Mike S M
authors.initials: MS
authors.lastname: Jetten
authors.affiliation: Department of Microbiology, Faculty of Science, Institute for Water and Wetland Research, Radboud University Nijmegen, Netherlands.
authors.forename: Huub J M
authors.initials: HJ
authors.lastname: Op den Camp
authors.affiliation: Department of Microbiology, Faculty of Science, Institute for Water and Wetland Research, Radboud University Nijmegen, Netherlands.
authors.forename: Laura
authors.initials: L
authors.lastname: van Niftrik
keywords: Methylomirabilis; bacteriophage; bioreactor; ultrastructure; viral metagenome