Genetic and physiological characterization of the intestinal bacterial microbiota of Bluegill (Lepomis macrochirus) with three different feeding habits.

Bluegill (Lepomis macrochirus) in Lake Biwa, Japan, feed on benthic invertebrates (benthivorous type), aquatic plants (herbivorous type), and zooplankton (planktivorous type). To evaluate the effect of food on intestinal bacterial microbiota, we characterized and compared the intestinal microbiota of these three types of bluegill in terms of community-level physiological profile (CLPP) and genetic structure. The CLPP was analyzed using Biolog MicroPlates (Biolog, Inc., Hayward, CA, USA), and multivariate analysis of variance revealed that the CLPP of intestinal microbiota differed significantly between any pairs of the three types of bluegill. The genetic profiles were analyzed by temperature gradient gel electrophoresis of polymerase chain reaction (PCR)-amplified 16S rDNA fragments, and multidimensional scaling indicated the existence of specific intestinal bacterial structures for both the benthivorous and the planktivorous types. These results suggest that the host's feeding habit can be one factor controlling the intestinal microbiota of fish in the natural environment.