The synergistic effects of Lactobacillus casei HDS-01-konjac glucomannan synbiotic: probiotic potential and in vitro fecal fermentation

The study used the mannanase-producing Lactobacillus casei HDS-01 as the probiotic component and combined it with konjac powder, which contains konjac glucomannan (KGM), to create a synergistic synbiotic. The aim was to investigate its probiotic potential and the changes in gut microbiota and short-chain fatty acids (SCFAs). The results indicated that KGM selectively stimulated the growth of L. casei HDS-01, confirming their synergistic effect. The survival rate of L. casei HDS-01 at pH levels of 2.5–5.5, bile salt concentration of 0–0.35 g/L, and NaCl concentration of 1–8 g/L reached more than 55 %, suggesting that L. casei HDS-01 can survive in the gastrointestinal tract. Furthermore, the colonisation ability of L. casei HDS-01 in the intestinal tract was significantly enhanced by KGM. The antidigestive property of konjac oligo-glucomannan (KOGM) in gastric juice was better than that of inulin, with 94 % of KOGM expected to reach the jejunum of the small intestine after entering the human digestive system. In vitro fecal fermentation results indicated that the L. casei HDS-01-KGM synbiotic effectively promote the proliferation of gut SCFAs-producing bacteria (2.43 × 10 8  CFU/mL) and increase SCFAs production. The contents of acetic acid (7.68 ± 0.04 μg/mL), propionic acid (6.72 ± 0.03 μg/mL) and butyric acid (4.37 ± 0.06 μg/mL) were higher than those of the other treatment groups. Meanwhile, L. casei HDS-01-KGM synbiotic could enhance the population of beneficial bacteria, such as Pediococcus while significantly reducing harmful bacteria, such as Shigella . These results demonstrate the synergistic effect of L. casei HDS-01-KGM synbiotic and establish the foundation for its application in the food industry