On the role of bacterial gut microbiota from supralittoral amphipod Talitrus saltator (Montagu, 1808) in bioplastic degradation.

Despite the promise of a reduced environmental impact, bioplastics are subjected to dispersion and accumulation similarly to traditional plastics, especially in marine and coastal environments. The environmental impact of bioplastics is attracting increasing attention due to the growing market demand. The ability of the supralittoral amphipod Talitrus saltator to ingest and survive on pristine starch-based bioplastic has already been assessed. However, the involvement of the gut microbiota of this key coastal species in making bioplastics a dietary supplement, remains unknown. In this study, we investigated the modification of T. saltator gut microbiota following bioplastic ingestion and the effect of this change on the modification of their chemical composition. Groups of adult amphipods were fed with: 1 - two different kinds of starch-based bioplastic; 2 - a 50 %/50 % chitosan-starch mixture; and 3 - paper and dry-fish-food. Freshly collected, unfed individuals were used as control group. Faecal pellets from the amphipods were collected and characterized using ATR-FTIR spectroscopy. DNA was extracted from gut samples for metagenomic analysis. Spectroscopic investigation suggested a partial digestion of polysaccharide components in the experimental polymeric materials. The analysis of the gut microbiota revealed that bioplastic feeding induced modification of sandhopper's gut microbial communities, shifting the abundance of specific microbial genera already present in the gut, towards bacterial genera associated with plastic/bioplastic degradation, especially in groups fed with starch-based bioplastics. Overall, our results highlight the involvement of T. saltator's gut microbiota in bioplastic modification, providing new insights into the potential role of microbial consortia associated to sandhoppers in bioplastic management.