Abstract:
To overcome the restricted bioactivity of konjac glucomannan (KGM) caused by its high molecular weight, KGM-degrading bacteria were isolated from konjac cultivation soil, diseased konjac tubers, and liquor fermentation systems. The probiotic potential of these strains was assessed based on acid and bile salt tolerance, resistance to simulated gastrointestinal fluids, and safety evaluations. It was found that all four isolated strains exhibited excellent KGM-degrading capability, along with high tolerance to acidic conditions, bile salts, and simulated digestive fluids, a safe profile, antibiotic sensitivity, antibacterial activity, and strong adhesion capability to human colon cancer Caco-2 cells. Through morphological and 16S rDNA analyses, strain JQ4 was identified as
Bacillus halotolerans, whereas strains JZ6 and JZ8 were classified as
Bacillus paralicheniforms, and RF8 was confirmed as
Bacillus licheniforms. Notably,
Bacillus licheniformis RF8 exhibited
β-mannanase activity of 49.92±0.06 U/mL, demonstrated survival rates of 96.57% and 82.22% after 3 h in simulated gastric fluid (pH2.0) and 6 h in simulated intestinal fluid (pH8.0), respectively, and showed a high adhesion capability to human colon cancer Caco-2 cells of 362.76±4.31 CFU/cell. In conclusion, four
Bacillus strains with both efficient KGM-degrading capacity and promising probiotic characteristics were successfully obtained. These findings provide valuable microbial resources and a theoretical foundation for the development of functional oligosaccharides and novel probiotic formulations.