MODIFICATION OF COLONIC FERMENTATION BY BIFIDOBACTERIA AND PH IN-VITRO - IMPACT ON LACTOSE METABOLISM, SHORT-CHAIN FATTY-ACID, AND LACTATE PRODUCTION

Colonic fermentation plays an important role in the prevention of lact ose intolerance and intestinal disorders. The objectives of this study were to evaluate whether supplementation with bifidobacteria modify c olonic fermentation of lactose and short-chain fatty acid production a nd to assess influence of the pH in an in vitro continuous culture sys tem. There was a significantly greater reduction in lactose concentrat ions a t pH 6.7 than that at either pH 6.2 or pH 5.7, accompanied by t he highest beta-galactosidase activity and D-lactate production. Bifid us supplementation reduced lactose and D-lactate concentrations and in creased acetate production at pH 6.7, The study demostrates that lacto se is rapidly metabolized by colonic bacteria and lactose fermentation in vitro is pH dependent with a maximum rate at pH 6.7. Bifidobacteri a supplementation may have the potential to improve lactose fermentati on and to manipulate SCFA and lactate production.