Aquaculture ecosystem microbiota at the water-fish interface: the case-study of rainbow trout fed with Tenebrio molitor novel feed formulation

Using 16S rRNA metabarcoding, we comprehensively analyzed the microbiota of water, tank biofilm, fish mucus, fish cutis, and feed samples. Core microbiota analysis revealed the presence of a highly reduced core shared by all sample sources, constituted by Aeromonas spp., for both control group and novel feed test group. Network analysis indicated that samples clustered based on sample source, with no significant differences related to the feed formulation tested. Thus, different feed formulations seemed to not affect the environment (water and tank biofilm) and the fish (cutis and mucus) microbiota. Trying to disentangle the contribution of feed at a finer scale, we performed a differential abundance analysis, and we observed differential enrichment/impoverishment in specific taxa, comparing the samples belonging to the control diet group and the insect-based diet group. These data provide evidence for a link between the environment and the fish, and subtle but significant differences exerted by feed formulation.