The Combination of Host-Associated Bacillus megaterium R32 and Stachyose Promotes the Intestinal Health of Turbot ( Scophthalmus maximus . L)

An 8-week feeding trial was conducted to investigate the effects of host-associated R32 and stachyose on the intestinal mucosal defense system of turbot ( . L). Three isonitrogenous and isolipidic diets were formulated: control diet (C), control diet with 1.0 × 10 CFU/g R32 (RC), and 1.0 × 10 CFU/g R32 + 1.5% stachyose (RS) supplementation separately. The results showed that diets RS and RC significantly inhibited the expression of cell development and apoptosis-related genes ( , , , ); diets RS and RC significantly increased the expression of intestinal tight junction protein , while RS group significantly decreased the expression of ; diets RS and RC significantly decreased the expression of proinflammatory factors ( , , ), diet RS also significantly decreased the expression of and , and increased the expression of . 16s rRNA gene sequencing results showed that diets RS and RC significantly decreased the abundance of conditional pathogenic bacteria ( , , ). Among them, the abundance of in the RS group was the highest. It is concluded that the combination of stachyose and R32 had a more positive effect on intestinal cell development and barrier function and strengthened the intestinal mucosal defense system of turbot.