Hemifusus tuba (Gmelin, 1791) is a commercial marine gastropod that undergoes an ontogenetic dietary transition from egg-capsule nutrition (lecithotrophy) to herbivory and finally to lifelong carnivory. How associated microbiota respond to this feeding habit transition remained largely unexplored. Here, we characterized taxonomic composition, diversity and functional prediction of associated microbiota in H. tuba across three dietary stages (CK, egg-capsule nutrition or lecithotrophic; He, herbivory; Ca, carnivory) using 16S rRNA amplicon sequencing. A total of 457,412 high-quality reads from 14 libraries were clustered into 12,091 OTUs, identifying 811 genera within 38 phyla. And five dominant phyla ( Proteobacteria , Bacteroidota , Firmicutes , Actinobacteriota , and Planctomycetota ) accounted for 99% of total abundance and formed the core microbiota. Alpha diversity increased from CK to He and peaked in Ca, whereas beta diversity analyses consistently separated Ca from CK and He, indicating microbiota restructuring following the transition to carnivory. During the feeding habit transition, Proteobacteria and Planctomycetota increased, while Bacteroidota , Firmicutes , and Actinobacteriota declined. LEfSe identified Hyphomicrobiales / Bradyrhizobiaceae , Burkholderiales / Betaproteobacteria , and Rhodobacterales / Roseobacteraceae as biomarkers for CK, He, and Ca, respectively. PICRUSt2 functional predictions indicated that CK enriched for tryptophan and butyrate metabolism and fatty acid degradation, whereas Ca appeared to be enriched for methane and pyruvate metabolism and the TCA cycle. These diet-associated microbiome shifts might facilitate nutrient utilization and energy metabolism during feeding habit transition, and provided microbial candidates for feed optimization in H. tuba domestication.
Wu et al. (Thu,) studied this question.