Gut bacterial assemblages of freshwater macroinvertebrate functional feeding groups

Little is known about the impacts of diet and environment on the composition and stability of gut microbial assemblages among freshwater macroinvertebrate functional feeding groups, compared to terrestrial counterparts. In this study, we compared gut microbial assemblages among functional feeding groups and environmental/dietary materials (biofilm and bacterioplankton) within and across two Northeastern Ohio streams differing in environmental conditions, following partial 16S rRNA sequence data analyses. Four functional feeding groups (filter feeders, grazers/collectors, omnivores, and predators) were uncovered in both streams, with significant differences in gut microbial community compositions among functional feeding groups within streams, and significant similarities in gut microbial community compositions between the same functional feeding groups across streams. Observed differences and similarities among functional feeding groups may be attributed to group-specific internal sorting processes due to physical and chemical properties (such as pH and oxygen levels) of the gut, which impact successful bacterial colonization. Results from this study provide insights into the impacts of diet and environment on the composition and stability of freshwater macroinvertebrate gut microbial assemblages. Results also provide a basis for further studies investigating initial establishment and colonization of gut microbiota across developmental stages, and potential gut microbial functions of importance to freshwater macroinvertebrate hosts.