Production of Short-chain Fatty Acids from Dietary Lactosucrose in the Hindgut and Its Effects on Digestive Organs of a Marine Teleost, Red Sea Bream Pagrus major

Abstract

Gut microbes of red sea bream Pagrus major can ferment lactosucrose, an indigestible and fermentable oligosaccharide, in vitro. Dietar y lactosucrose (LS) increases mechanical strength of intestinal tunica muscularis of this fish. Thus, the aims of this study were to evaluate hindgut fermentation of dietary LS by the intra-luminal existence of short-chain fatty acids (SCFA), and to confirm the effect of this sugar on weight of digestive organs in a marine teleost, red sea bream. Fish of approximately 70g body weight were randomly assigned to two groups and fed either a commercial diet (control group) or a commercial diet supplemented with 0.24 g/100 g LS (LS group) for two months. Fish fed LS had greater SCFA in intestinal contents than did control fish (P< 0.001). The ratios of SCFA/total organic acids of hindgut contents exceeded 55% in fish fed LS and were significantly greater than in control fish (P< 0.01). Contents of free (not bonded) water in hindgut contents of fish fed LS were lower than in control fish (P< 0.05). Fish fed LS had heavier stomachs and intestines than in fish fed control diet (P< 0.05). The above results suggest that hindgut microbes of red sea bream can ferment LS to produce SCFA. Fermentation of this sugar should affect intestinal water absorption by lowering free water content and affect digestive organs by SCFA fermentation metabolites.