Functional characterization of gut bacteria essential for development of mosquitoes

The mosquito gut harbors a low diversity microbial community comprised primarily of aerobic bacteria.  We recently reported that axenic mosquito larvae devoid of this community fail to develop past the first instar.  We also reported that several bacterial community members and one non-community member, Escherichia coli, successfully colonize axenic larvae and rescue development. However, little is known about how gut bacteria are acting to regulate growth processes in mosquito larvae. Here we describe a density-dependent relationship between bacteria levels in the gut and larval molting events. We also show that a set of E. coli K-12 single-gene deletion mutants defective in rescuing larval development are unable to colonize the larval gut, which suggests that incipient colonization is required for bacterial rescue of mosquito development.