ena-STUDY-Center of Applied Geosciences-19-08-2014-16:41:51:039-706
Ribosomal tag pyrosequencing of DNA and RNA reveals  ‘rare’ taxa with high protein synthesis potential in the sediment of a hypersaline lake in Western Australia
Hypersaline lakes are extreme habitats for microbial life. Nonetheless, the water bodies and sediments of salt lakes harbor highly diverse microbial communities. Little is known about the potential activity of the microbial populations in these ecosystems. Ribosomal tag libraries based on DNA and RNA extracted from the sediment of the hypersaline Lake Strawbridge showed that the microbial community is dominated by the bacterial phyla Proteobacteria, Firmicutes and Bacteroidetes and the archaeal classes Halobacteria and Thermoplasmata. Community richness and evenness revealed a higher diversity of the bacterial community than the archaeal community. Rank abundance curves of DNA-based, but not RNA-based libraries, displayed a tail of low abundance taxa, supporting the existence of a ‘rare’ biosphere. Both, the bacterial and archaeal community comprised operational taxonomic units with high RNA/DNA ratios providing evidence for the presence of ‘rare’ but potentially ‘active’ taxa. Among the ‘rare’ bacterial taxa Halomonas, Salinivibrio, Idiomarina and Planococcus showed the highest protein synthesis potential. The rare but potentially ‘active’ archaeal community comprised OTUs related to the KTK 4A cluster and the Marine Benthic Groups B and D. This study represents the first molecular analysis of the microbial diversity and protein synthesis potential of rare microbial taxa in a hypersaline sediment ecosystem.
Hypersaline lakes are extreme habitats for microbial life. Nonetheless, the water bodies and sediments of salt lakes harbor highly diverse microbial communities. Little is known about the potential activity of the microbial populations in these ecosystems. Ribosomal tag libraries based on DNA and RNA extracted from the sediment of the hypersaline Lake Strawbridge showed that the microbial community is dominated by the bacterial phyla Proteobacteria, Firmicutes and Bacteroidetes and the archaeal classes Halobacteria and Thermoplasmata. Community richness and evenness revealed a higher diversity of the bacterial community than the archaeal community. Rank abundance curves of DNA-based, but not RNA-based libraries, displayed a tail of low abundance taxa, supporting the existence of a ‘rare’ biosphere. Both, the bacterial and archaeal community comprised operational taxonomic units with high RNA/DNA ratios providing evidence for the presence of ‘rare’ but potentially ‘active’ taxa. Among the ‘rare’ bacterial taxa Halomonas, Salinivibrio, Idiomarina and Planococcus showed the highest protein synthesis potential. The rare but potentially ‘active’ archaeal community comprised OTUs related to the KTK 4A cluster and the Marine Benthic Groups B and D. This study represents the first molecular analysis of the microbial diversity and protein synthesis potential of rare microbial taxa in a hypersaline sediment ecosystem.