Symbiotic bacterial communities of zooplankters from Lake Biwa, Japan

Abstract

Microbial symbionts play important roles for zooplankton by promoting nutrition, growth, and reproduction. We report bacterial communities from bodies and feces of three zooplankton taxa (Eodiaptomus japonicus, Daphnia pulicaria, Cyclopoida spp.) from Lake Biwa using meta-barcoding analysis targeting the prokaryote-specific V4 region of 16S rDNA. A total of 669 bacterial OTUs were generated. Bacteria associated with the body and feces of E. japonicus were most divergent. The bacterial compositions of the bodies and feces in all three host taxa differed significantly. The bacterial phyla in the zooplankton bodies and feces were dominated by Proteobacteria, Bacteroidetes, Firmicutes, and Actinobacteria. At lower taxonomic levels, the bacteria of bodies (in particular) and feces differed among zooplankton taxa. Prevalent bacteria of D. pulicaria and Cyclopoida spp. bodies were Aeromonadales (Gammaproteobacteria), and those of E. japonicus were dominated by Burkholderiales (Betaproteobacteria). Aeromonadaceae was the most dominant bacterial family in zooplankton bodies, while Pelagibacteraceae was dominant in feces. The bacterial communities present in the feces were similar among the taxa but differed from those found in the bodies of the animals themselves, implying that the feces contained transient bacteria passing through the digestive system. The bacterial composition associated with the zooplankton bodies may be related to the host’s feeding habits, habitat selection, and behavior.