Spatial Variation of Microbial Communities in Lake Tanganyika, Africa

Abstract

Lake Tanganyika is a 1400 m deep fresh water lake in Africa's rift valley containing the world's largest amount of anoxic freshwater. Anaerobic freshwater systems often contain unique endemic bacterial taxa, including candidate phyla, which can play a large role in the lake's biological processes. To better understand the poorly defined bacterial community composition (BCC) of Lake Tanganyika, we extracted DNA from filtered samples collected at multiple depths in 2013 and 2015 and then performed 16S rRNA gene amplicon sequencing. 16S sequencing results were analyzed to determine how the BCC varies horizontally and vertically across the lake. We found that the deep, anoxic regions of Lake Tanganyika harbor rich and even communities, the most abundant members of which were from the genus Synechococcus. Many candidate phyla such as TM6 and Omnitrophica(OP3) were also present, as well as numerous unclassified bacterial taxa.