RESUMEN

Bacterial mats formed by a colorless sulfur bacterium Thioploca sp. in the area of the Posolski Bank cold methane seep (southern Baikal) were -studied using electron microscopy and phylogenetic analysis. Morphologically the bacteria were identified as Thioploca ingrica.- Confocal microscopy of DAPI-stained samples revealed numerous rod-shaped, filamentous, and spiral microorganisms in the sheaths, as well as in- side and between the trichomes. Transmission electron microscopy revealed nonvacuolated bacteria and small cells-without cell envelopes within the sheath. Bacteria with pronounced intracytoplasmic membranes characteristic; of type I methanotrophs were observed at the outer side of the sheath. Based on analysis of the 16S rRNA gene sequences, the following phyla were idenified in the sheath community: Bacteroidetes, Nitro- spira, Chloroflexi, Planctomycetes, Verrucomicrobia,'y-, and 6-Proteobacteria, Euryarchaeota, Crenarchaeota, and Thaumarchaeota, as well as anammox bacteria. A hypothetical scheme of matter flows in the Lake Baikal bacterial mats was proposed based on the data on metabolism of the cultured homologues.

Asunto(s)

Agua Subterránea/microbiología , Lagos/microbiología , Consorcios Microbianos/fisiología , ARN Ribosómico 16S/genética , Thiotrichaceae/genética , Bacteroidetes/clasificación , Bacteroidetes/genética , Bacteroidetes/aislamiento & purificación , Chloroflexi/clasificación , Chloroflexi/genética , Chloroflexi/aislamiento & purificación , Crenarchaeota/clasificación , Crenarchaeota/genética , Crenarchaeota/aislamiento & purificación , Ecosistema , Euryarchaeota/clasificación , Euryarchaeota/genética , Euryarchaeota/aislamiento & purificación , Metano/química , Metano/metabolismo , Filogenia , Planctomycetales/clasificación , Planctomycetales/genética , Planctomycetales/aislamiento & purificación , Proteobacteria/clasificación , Proteobacteria/genética , Proteobacteria/aislamiento & purificación , Siberia , Thiotrichaceae/clasificación , Thiotrichaceae/aislamiento & purificación , Thiotrichaceae/ultraestructura , Verrucomicrobia/clasificación , Verrucomicrobia/genética , Verrucomicrobia/aislamiento & purificación