Fermentability of carbohydrates in an in vitro batch culture method using inocula from Nile tilapia (Oreochromis niloticus) and European sea bass (Dicentrarchus labrax)

This study investigated in vitro fermentability of wheat‐derived carbohydrates using inocula of Nile tilapia and European sea bass. Distal intestinal contents were incubated in bottles containing one of four fermentable substrates, i.e. glucose (GL), native wheat starch (WS), arabinoxylan (ABX) and whole wheat (WHT). Cumulative gas production was measured for 168 h. At the end of incubation, fermentation end‐products were measured. A monophasic model was fitted to the gas production profiles of each bottle, thereby allowing calculation of gas kinetic parameters. Total gas production (mL g^?1 organic matter) differed significantly between substrates for tilapia (GL: 268.9; WS: 388.0; ABX: 411.9; WHT: 413.2) and sea bass (GL: 338.6; WS: 189.3; ABX: 296.3; WHT: 264.0). Fermentation rates were highest for GL and lowest for WS, both for tilapia and sea bass. Fermentation of ABX and WHT yielded predominantly acetic and butyric acid, whereas GL and WS yielded also significant amounts of lactic acid. Ammonia (mL g^?1 organic matter) was highest for WHT (tilapia: 80.36; sea bass: 70.39) and lowest for GL (tilapia: 46.01; sea bass: 32.83). In conclusion, intestinal microbes from Nile tilapia and European sea bass have the potential to ferment carbohydrates. Large differences exist in fermentability and composition of fermentation end‐products between carbohydrates.