Bifidobacterium lactis Bb-12 and Lactobacillus salivarius UCC500 modify carboxylic acid formation in the hindgut of rats given pectin, inulin, and lactitol.

Abstract

The effect of Bifidobacterium lactis (Bb-12) and Lactobacillus salivarius (UCC500) on the formation of carboxylic acids (CAs) was studied in the hindgut of rats fed pectin, inulin of low solubility, and lactitol. When the pectin diet was supplemented with Bb-12, the formation of CAs was larger throughout the colon of rats, due to increased formation of acetic acid (P < 0.01) and, in the distal part of the colon, also because of propionic and butyric acids (P < 0.01). In rats fed pectin and UCC500, there was a shift in the formation of CAs from the cecum to the distal colon. Thus, the cecal pool of CAs in the rats was lower (P < 0.05), whereas the concentration of CAs in the distal part of colon was larger (P < 0.01) than without this strain. Concerning the slowly fermentable inulin, there was a greater formation of CAs in the cecum (P < 0.05) of rats, especially propionic acid, and a lower formation in the distal part of the colon (P < 0.01) when the diets were supplemented with Bb-12, whereas UCC500 had no effect except for a lower proportion of acetic acid in the distal part of the colon (P < 0.001). In rats fed lactitol and Bb-12, the concentration of CAs was lower in the distal part of colon (P < 0.001) than without this strain, whereas the cecal pool of CAs was greater in rats supplemented with UCC500 (P < 0.001). We conclude that the probiotic bacteria affect the amount, the pattern, and the site of release of CAs in the hindgut of rats, but the combination of pre- and probiotics is of great importance for the outcome.