AME 75:251-257 (2015)  -  DOI: https://doi.org/10.3354/ame01760

ABSTRACT: We examined bacterioplankton community composition (BCC) in 27 oligotrophic freshwater lakes with similar environments, located in the mountainous regions of eastern Japan. We determined BCC by the relative sequence abundance of each taxon using polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) targeting the 16S rRNA gene region. Using multiple regression analyses, we investigated the relative importance of environmental and geospatial processes on community assembly of the general bacterioplankton, as well as of the taxonomic groups Betaproteobacteria and Bacteroidetes. Both processes had significant relationships with community assembly. In particular, environmental processes were relevant, however small the variations among study sites. Community composition of Betaproteobacteria was mainly correlated with environmental factors, whereas that of Bacteroidetes was primarily associated with geospatial variables, such as the presence of Tsugaru Strait as a geographic barrier. Thus, inter-taxonomic differences are significant in assessing relationships of environmental and geospatial processes with freshwater BCC. Finally, our study provides evidence that biogeographic events are potentially significant for the distribution and diversity of microorganisms, as is the case with macroorganisms. These perspectives should be taken into consideration in order to fully understand bacterial community assembly.

KEY WORDS: Dispersal limitation · Environmental filtering · Geographic barrier · Metacommunity · Microbial biogeography