Heterotrophic Microbiota from the Oligotrophic Waters of Lake Vostok, Antarctica

Abstract

Lake Vostok is the deepest lake of Antarctica but has poor accessibility for study due to a thick glacial cover, however, water samples of this lake have become available for study just recently. Previously, only the microbiome of the ice cover samples was characterized. Here we report results of bacteriological seeding with subsequent identification of the heterotrophic microorganisms (bacteria and micellar fungi) present by 16S rDNA sequencing as well as results of a direct molecular study of the water microbiome. Surprisingly, the data obtained gave evidence of a predominant occurrence of common chemoorganotrophs that were rather psychrotolerant than psychrophilic. We isolated and described strains belonging to eight heterotrophic microbial species able to grow in a rich medium: six bacterial strains belonging to the species Microbacterium testaceum and Microbacterium trichothecenolyticum, Brevundimonas diminuta, Sphingomonas oligophenolica, Sphingomonas sp. and Sphingobium limneticum; and two fungal strains belonging to Dendryphion sp. and Cladosporium fusiforme. Direct study of 16S rDNA purified water samples confirmed the predominance of the Brevundimonas, Microbacterium, Bradyrhizobium, and Bacillus (Bacillus cereus) genera.

Biodiversity of UV-Resistant Bacteria in Antarctic Aquatic Environments

“…nov., which was isolated from the Mediterranean Sea [90]. Although the majority of Antarctic Brevundimonas strains reported in the literature displayed no pigmentation [35,[91][92][93], in this study, all three isolates, RA4, ED-ICE-A-RA1, and IN-H2O-B-RA3, showed a reddish orange pigmentation, as has already been reported in other environments [94,95]. Some orange Brevundimonas strains isolated from aquatic environments in Japan were producers of astaxanthin and adonixanthin [94].…”

“…Bacillus sp. ED-ICE-A-RA1B was phylogenetically close to Bacillus cereus, which has been found in the waters of Lake Vostok, Antarctica [93]. Staphylococcus spp.…”

Rice leaf endophytic Microbacterium testaceum: Antifungal actinobacterium confers immunocompetence against rice blast disease

“…The endophytic M. testaceum isolated from rice leaf was found clustered with a potato leaf endophytic M. testaceum StLB037 ( Morohoshi et al, 2009 ). Before the present study, M. testaceum was reported in diverse habitats like water ( Epova et al, 2022 ), soil ( Yang et al, 2014 ), tannery effluents ( Elahi et al, 2019 ), phyllosphere ( Sahu et al, 2021a , b ), plant endosphere ( Kumar et al, 2021b ), and sometimes as an opportunistic pathogen in clinical samples ( Leal et al, 2016 ). We further studied the endophytism of the bacterium in rice plants using gfp-tagged M. testaceum D18::gfp that could be visualized in the root, stem as well as leaf tissues.…”

The Effects of a High Concentration of Dissolved Oxygen on Actinobacteria from Lake Baikal

“…There are only several natural locations on the planet where oxygen oversaturation can exist, such as the freshwater lakes of Antarctica (such as Lake Vostok and Radok Lake) and Lake Baikal. The microbial compositions of Lake Vostok and Radok Lake have been published and partially compared with the microbial composition of Lake Baikal, where a common group of bacteria related to the Actinobacteria phylum was detected [ 47 , 48 , 49 , 50 ]. In the mentioned lakes, we probably have to deal with a unique group of extremophilic bacteria related to oxyphiles.…”