Probiotic Production by Mixed Culture of Lactic Acid Bacteria and Yeast

บทคัดย่อ

Batch mixed culture of probiotic lactic acid bacteria (LAB), Enterococcus faecium PR–2 and/or Lactobacillus plantarum IG–3 and lactate assimilating yeast (MB–1 or KN–1 or KN–2) is a mean to maintain pH in culture broth suitable for the LAB growth. The result in this study showed that almost all the probiotic cell productions of mixed culture (i.e. mixed culture of LAB strains and mixed culture of LAB and lactate assimilating yeast) in MRS-sucrose medium were higher than those of pure culture. Among the combinations of these microorganisms, growth of the mixed culture of Ent. faecium PR–2 and MB–1 was the highest and the viable cell counts of LAB increased 2.58 log CFU/ml within 24 h. It was 2 times higher than the cell increment of only Ent. faecium PR–2 (1.27 log CFU/ml). The mixed culture and pure culture were compared for acid and bile tolerance under simulated conditions of broiler gastrointestinal (GI) tract. After 3h incubation at pH 2.5, the viable LAB cells of mixed culture of Ent. faecium PR–2 and L. plantarum IG–3 and KN–1 were the highest (100 % survival). On the other hand, the survival of LAB in mixed culture of L. plantarum IG–3 and KN–1, L. plantarum IG–3 and MB-1 were the highest tolerance towards 0.3% ox bile for 18h (94 % survival). Moreover, the survived cells of LAB of mixed culture after bile treatment were found to have antagonistic effect against indicator strains of food born pathogens.