Probiotic potential and amylolytic properties of lactic acid bacteria isolated from Chinese fermented cereal foods

This study investigated the probiotic potential and amylase properties of amylolytic lactic acid bacteria (ALAB) isolated from fermented cereal-based foods in China. Of 132 LAB isolates screened for amylase production, three (430, 445, and 472) were found to have high amylase activities (8.15, 9.23, and 8.06 U/mL in MRS-1% starch broth, respectively). These three strains were identified as Lactobacillus plantarum by 16 S rRNA sequencing. Optimization of the starch content in the culture broth, pH, and temperature during fermentation revealed that the highest amylase activity (15.89 ± 0.51 U/mL) was found in L. plantarum 445. Moreover, the three ALAB isolates were assessed for their probiotic properties, tolerance to low pH, bile salt resistance, and antimicrobial and aggregation activities. All three ALAB isolates showed good survival at pH 2.0 and 3.0 and were resistant to 0.3% and 0.6% bile salts after 48 h of incubation. They also had different antimicrobial activities against five food-borne pathogens and similar intrinsic and non-transmissible antibiotic susceptibilities. The isolates had higher auto-aggregation ability but weaker co-aggregation ability than the reference strain, Lactobacillus rhamnosus ATCC 53103. These data demonstrate that the three ALAB isolates possess potential probiotic characteristics, suggesting that they are suitable candidates for cereal-based probiotic products and starter cultures for improving the cereal fermentation process.