Effect of a novel postbiotic containing lactic acid bacteria on the intestinal microbiota and disease resistance of rainbow trout (Oncorhynchus mykiss)

Objective This study was aimed to assess the effect of a novel postbiotic on bacterial community composition and structure within the intestinal ecosystem of rainbow trout ( Oncorhynchus mykiss ), as well as evaluate its capacity to protect rainbow trout from Lactococcus garvieae infection. Results After 30 days of dietary postbiotic supplementation, high-throughput 16S rRNA gene sequencing revealed that bacterial community composition, diversity and richness were significantly higher in treated fish than in control fish. The proportion of sequences affiliated to the phylum Tenericutes, and to a lesser extent, the phyla Spirochaetes and Bacteroidetes was increased in fish fed a postbiotic-enriched diet compared to control fish, whereas the abundance of Fusobacteria was higher in control fish. Moreover, the treated fish showed significantly ( p