Removal of 3-methylindole by lactic acid bacteria in vitro

Abstract

3-Methylindole (3MI) is a substance with an unpleasant odor that is found in intact male pigs and is known to negatively affect consumers of pork. The growth of four strains of lactic acid bacteria [<i>Lactobacillus brevis</i> 1.12 (<i>L. brevis</i> 1.12), <i>L. plantarum</i> 102, <i>L. casei</i> 6103 and <i>L. plantarum</i> ATCC8014] in incubation medium with 3MI was studied. The four strains were tested for their ability to remove 3MI from the medium. The growth of <i>L. brevis</i> 1.12 remained steady as the levels of 3MI increased 3MI from 0.2 to 1.0 <i>μ</i>g/ml. The 3MI removal ability of <i>L. brevis</i> 1.12 was the strongest among the four strains, and the highest removal rate was 65.35±0.3% in 1 ml incubation medium containing 1.0 <i>μ</i>g/ml 3MI for 120 h. Furthermore, the supernatant fluid of the fermentation broth of <i>L. brevis</i> 1.12 had a stronger ability to remove 3MI than cell pellets and cell extracts and the removal rate was 14.4±0.3% in 24 h. Further results indicate that the mode of removal of 3MI was not through the physical binding of cells by <i>L. brevis</i> 1.12.