Exploitaton of the Functional Properties of Leuconostoc mesenteroides and Lactobacillus plantarum as Probiotic using Soyabeans Flour as Vehicle

Abstract

Lactic acid bacteria produce a variety of antimicrobial compounds such as acetic acid, hydrogen peroxide, diacetyl on them as a natural competitive means to overcome other microorganism sharing the same niche. Seven different strains of Leuconostoc mesenteroides and Lactobacillus plantarum were screened for their ability to produce enzymes and metabolites. They were also screened for their ability to withstand some physiological stress like acid tolerance, temperature, salt concentration and antibacterial activity. Leuconostoc mesenteroides S3 and Lactobacillus plantarum Yh1produced values significantly different to other five isolates and they were selected. These functional properties were exploited in the fermentation of soyabean in order to obtain a probiotic vehicle. The selected isolates were used as starter both singly and in consortium. This research work also finds out the suitability of soya beans flour as a vehicle for probiotic microorganisms (Lactobacillus plantarum and Leuconostoc mesenteroides). The cleaned, dried and roasted soya beans were grinded to flour. The soya beans flour was fermented with Lactobacillus plantarum and Leuconostoc mesenteroides and there was mass increase in lactic acid counts in the fermented soya beans flour store at room temperature. All lactic acid fermented soya beans flour recorded increase at room temperature but slight reduction in number at refrigerator temperature from day 0 to day 14 of storage. Lactobacillus plantarum fermented soya beans flour (LPFSB) recorded increase from 5.9x105 (day 0) to 10.60x105cfu/g (day 14), while the L. plantarum stored at refrigeration temperature had 5.9x105cfu/g on (day 0) to 5.5x105cfu/g on day 14. The L. plantarum and consortium of both starters used were observed to have considerable increase in cell growth after storage, therefore this satisfies the criteria for good probiotic bacteria. Leuconostoc mesenteroides fermented soya beans slightly reduced in cell number at pH of 2 but others survived well at acidic pH and 10% bile. The cell number reduced from 4.8x106 (initial) to 4.2x106 (final). The pH of the intestine ranges from 2.5 to 3.5 and the starter culture used survive this pH and the bile product which shows greatly that they can serve as probiotic in the treatment of infection in gastrointestinal tract .