The Gut Microbiota of Helix aspersa

The Gut Microbiota of Helix aspersa. The gut microbiota plays an important role in the host organism’s well-being, contributing to the host’s immunity and metabolism. An individual’s total gut microbiota is dynamic, fluctuating in response to changes in diet and environmental stressors; however, a host often has a subset of gut microorganisms, known as the core gut microbiome, which is consistent among individuals in a population. To study the gut microbiota, we are using the common garden snail, Helix aspersa, as our model organism. In the past, culture-based studies have been used to identify bacteria from the gut of Helix aspersa raised on processed food sources, which can alter the gut microbiota. Little has been done using metagenomics to determine the natural gut microbiota or identify a core microbiome. We analyzed 16S bacterial diversity in the feces of wild-caught snails using high-throughput Illumina sequencing of the V1 and V2 variable regions. Our results show a gut microbiota dominated by Gammaproteobacteria, particularly members of genus Buttiauxella. This finding was notable in that several early culture-based studies identified this genus as snail specific. More recent DNA-based work has identified this genus at low levels in soil and water environments. Given these data, we assessed the microbial community present on the snail food source, confirming low levels of Buttiauxella and high levels of Pseudomonas. This finding suggests that Helix selectively uptake microbes from their food-source and/or avoid potentially harmful Pseudomonas. We are using FISH microscopy and plating techniques to study changes in the gut microbiota of individual snails in response to changes in their feeding regimen, and exposure to antibiotics or bacterial stressors