Comparative study of Caspian roach (Rutilus rutilus caspicus) fry gut microbiota modulation following administration of galacto- and fructooligosaccharide prebiotics

Modulation of intestinal microbiota toward potentially beneficial communities (probiotics) positively affects fish physiology and health status. Different prebiotics showed contradictory effects on intestinal microbiota. The present study investigates the effects of different levels of two prebiotics, galacto- and fructooligosaccharide on intestinal microbiota of Caspian roach fry which is a commercially valuable species of Caspian sea. The study was performed as a randomized design with 5 treatments and 3 replications in which Caspian roach were fed different levels, 0, 1, and 2% of galacto- and fructooligosaccharide prebiotics for 6 weeks. At the end of the trial culture, analysis of intestinal microbiota include lactic acid bacteria levels, total bacteria as well as proportion of LAB were performed by using MRS agar, Plate count agar media. Administration of different levels of galacto- and fructooligosaccharide had no significant effects on total bacteria of intestinal microbiota (P > 0.05). The lactic acid bacteria levels significantly increased compared to control group following prebiotics administration in diet (P > 0.05). LAB levels in galactooligosaccharide treatment were higher than those of fructooligosaccharide treatment. The highest LAB proportion in intestinal microbiota was observed in roach fed diet which contains 2% galactooligosaccharide (P > 0.05).Discussion and The results of the present study revealed that prebiotics can be used for modulation of Caspian roach intestinal microbiota toward beneficial bacterial communities. Also, the results showed that galactooligosaccharide was more efficient than fructooligosaccharide in case of modulation of intestinal microbiota and elevation of LAB levels.