Microbial Ecology, University of Vienna | Hunting microbes since 2003

Time 2020-10-09 21:05:46

Web Name: Microbial Ecology, University of Vienna | Hunting microbes since 2003

WebSite: http://www.microbial-ecology.net

ID:76313

Keywords:

University,of,Microbial,

Description:

We seek to understand the role of microorganisms in Earth s nutrient cycles and as symbionts of other organisms Bacterial symbionts of amoebae and the evolution of the intracellular lifestyleMore Listening in on conversations between animals and the microbes they can t live without We spent a nice day in the Vienna woods with a picknick at the Circle of Life Trees 'Lebensbaumkreis'. Talking trees and a great opportunity to reload some safe social... Lebensbaumkreis am Himmel We cordially welcome Elisabeth (Liz) Hambleton and Dimitri Kits as new group leaders at DOME. We are looking foward to many exciting collaborations on microbial symbiosis and physiology in our endeavour... The Doctoral School in Microbiology and Environmental Sciences offers 15 fully funded PhD positions in diverse research areas ranging from molecular microbiology, ecology, computational and evolutionary biology to environmental geosciences.... Chemolithoautotrophic nitrite-oxidizing bacteria (NOB) are key players in global nitrogen and carbon cycling. Members of the phylum Nitrospinae are the most abundant, known NOB in the oceans. To date, only two closely affiliated Nitrospinae species have been isolated, which are only distantly related to the environmentally abundant uncultured Nitrospinae clades. Here, we applied live cell sorting, activity screening, and subcultivation on marine nitrite-oxidizing enrichments to obtain novel marine Nitrospinae. Two binary cultures were obtained, each containing one Nitrospinae strain and one alphaproteobacterial heterotroph. The Nitrospinae strains represent two new genera, and one strain is more closely related to environmentally abundant Nitrospinae than previously cultured NOB. With an apparent half-saturation constant of 8.7±2.5 µM, this strain has the highest affinity for nitrite among characterized marine NOB, while the other strain (16.2±1.6 µM) and Nitrospina gracilis (20.1±2.1 µM) displayed slightly lower nitrite affinities. The new strains and N. gracilis share core metabolic pathways for nitrite oxidation and CO2 fixation but differ remarkably in their genomic repertoires of terminal oxidases, use of organic N sources, alternative energy metabolisms, osmotic stress and phage defense. The new strains, tentatively named “Candidatus Nitrohelix vancouverensis” and “Candidatus Nitronauta litoralis”, shed light on the niche differentiation and potential ecological roles of Nitrospinae. The class Deltaproteobacteria comprises an ecologically and metabolically diverse group of bacteria best known for dissimilatory sulphate reduction and predatory behaviour. Although this lineage is the fourth described class of the phylum Proteobacteria, it rarely affiliates with other proteobacterial classes and is frequently not recovered as a monophyletic unit in phylogenetic analyses. Indeed, one branch of the class Deltaproteobacteria encompassing Bdellovibrio-like predators was recently reclas- sified into a separate proteobacterial class, the Oligoflexia. Here we systematically explore the phylogeny of taxa currently assigned to these classes using 120 conserved single-copy marker genes as well as rRNA genes. The overwhelming majority of markers reject the inclusion of the classes Deltaproteobacteria and Oligoflexia in the phylum Proteobacteria. Instead, the great majority of currently recognized members of the class Deltaproteobacteria are better classified into four novel phylum-level lineages. We propose the names Desulfobacterota phyl. nov. and Myxococcota phyl. nov. for two of these phyla, based on the oldest validly published names in each lineage, and retain the placeholder name SAR324 for the third phylum pending formal description of type material. Members of the class Oligoflexia represent a separate phylum for which we propose the name Bdellovibrionota phyl. nov. based on priority in the literature and general recognition of the genus Bdellovibrio. Desulfobacterota phyl. nov. includes the taxa previously classified in the phylum Thermodesulfobacteria, and these reclassifications imply that the ability of sulphate reduction was vertically inherited in the phylum Thermodesulfobacteria rather than laterally acquired as previously inferred. Our analysis also indicates the independent acquisition of predatory behaviour in the phyla Myxococcota and Bdellovibrionota, which is consistent with their distinct modes of action. This work represents a stable reclassification of one of the most taxonomically challenging areas of the bacterial tree and provides a robust framework for future ecological and systematic studies.Waite DW, Chuvochina M, Pelikan C, Parks DH, Yilmaz P, Wagner M, Loy A, Naganuma T, Nakai R, Whitman WB, Hahn MW, Kuever J, Hugenholtz P2020 - Int J Syst Evol Microbiol, in press Populations of the bacterium Vibrio cholerae consist of dozens of distinct lineages, with primarily (but not exclusively) members of the pandemic generating lineage capable of causing the diarrhoeal disease cholera. Assessing the composition and temporal dynamics of such populations requires extensive isolation efforts and thus only rarely covers large geographic areas or timeframes exhaustively. We developed a culture-independent amplicon sequencing strategy based on the protein-coding gene viuB (vibriobactin utilization) to study the structure of a V. cholerae population over the course of a summer. We show that the 26 co-occurring V. cholerae lineages continuously compete for limited space on nutrient-rich particles where only a few of them can grow to large numbers. Differential abundance of lineages between locations and size-fractions associated with a particle-attached or free-swimming lifestyle could reflect adaptation to various environmental niches. In particular, a major V. cholerae lineage occasionally grows to large numbers on particles but remain undetectable using isolation-based methods, indicating selective culturability for some members of the species. We thus demonstrate that isolation-based studies may not accurately reflect the structure and complex dynamics of V. cholerae populations and provide a scalable high-throughput method for both epidemiological and ecological approaches to studying this species.Kirchberger PC, Orata FD, Nasreen T, Kauffman KM, Tarr CL, Case RJ, Polz MF, Boucher YF2020 - Environ. Microbiol., in press Josh NeufeldDepartment of Biology, University of Waterloo, Canada19.03.202012:00 hWebinar Laura Lehtovirta-MorleyUniversity of East Anglia30.01.202012:00 hLecture Hall HS2, UZA1, Althanstrasse 14, 1090 Wien David RichardsonUniversity of East Anglia, Norwich Research Park, Norwich, UK23.01.202012:00 hLecture Hall HS2, UZA1, Althanstrasse 14, 1090 Wien

TAGS:University of Microbial 

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