Effects of oxidized konjac glucomannan on the intestinal microbial flora and intestinal morphology of Schizothorax prenanti

Abstract

Prenant’s schizothoracin (Schizothorax prenanti) is an important existemic commercial fish in Yangtze River. Oxidized konjac glucomannan (OKGM) is a kind of polysaccharide oxidative degraded from konjac glucomannan. The diet of S. prenanti was supplemented with 500, 1000, 2000, 4000, and 8000 mg/kg OKGM. After a 60-day feeding trial, Escherichia coli, Salmonella, Lactobacillus, and Bifidobacterium in the intestines of S. prenanti were quantified, and intestinal flora was analyzed using polymerase chain reaction–denaturing gradient gel electrophoresis (PCR-DGGE). Intestinal plica mucosa height, mucosa epithelial height, submucosa thickness, inner circular muscularis thickness, and outer longitudinal muscularis thickness were measured. In the foregut and midgut, Lactobacillus in the 2000, 4000, and 8000 mg/kg dose groups were significantly (P < 0.05) higher than that of the control group. In the hindgut, E. coli and Salmonella of the 4000 and 8000 mg/kg dose groups were significantly (P < 0.05) lower than those of the control group, but Lactobacillus and Bifidobacterium in these groups were significantly (P < 0.05) more than those of the control group. The bands from PCR-DGGE of the control and 500 mg/kg dose groups were found to be highly similar, as well as the 4000 and 8000 mg/kg dose groups. The intestinal length index of the 8000 mg/kg dose group was significantly (P < 0.05) lower than that of the control group. The plica mucosa height in the gut of the 8000 mg/kg dose group was significantly (P < 0.05) higher than that of the control group. The mucosa epithelial height and inner circular muscularis thickness in the midgut and hindgut of the 8000 mg/kg dose group were significantly (P < 0.05) higher than those of the control group. Hence, OKGM is beneficial to gut health. OKGM doses of 4000 and 8000 mg/kg in the diet significantly affected the intestinal morphology and intestinal microflora of S. prenanti, and the optimal dose was 8000 mg/kg.