Carbohydrate Hydrolytic Activity, Antimicrobial Resistance, and Stress Tolerance of Lacticaseibacillus paracasei BCRC-16100 and Lacticaseibacillus paracasei ZFM54 for Probiotics Using Genomic and Biochemical Approaches

Probiotics are microorganisms that are safe and stable under product development conditions and are used as adjuncts to food and drugs to promote health, including the acceleration of nutrient digestion. Here, we present evidence on the ability of two isolates, Lacticaseibacillus paracasei BCRC-16100 and L. paracasei ZFM54, to (1) enhance carbohydrate digestion, (2) tolerate processing conditions, and (3) demonstrate safety in terms of antimicrobial resistance (AMR). These approaches include whole-genome sequence (WGS) analysis, gene expression, and bioactivity assays. WGS revealed genes encoding enzymes involved in carbohydrate digestion, tolerance to processing conditions, and AMR. The ability of the two strains to digest carbohydrates was confirmed by glucose release when cultured alongside starch. The isolates also showed versatility across a range of temperatures and alcohol concentrations, indicating their suitability for product development. Genes cause AMR, particularly against vancomycin, through three mechanisms: transporter control, transcriptional regulation, and efflux pumps. Furthermore, promoter, gene expression, and transposable element analyses showed that some upregulated AMR genes in the presence of antimicrobials were transposable. Altogether, we show the potential of the two isolates for incorporation into products as probiotics to improve carbohydrate digestion, while considering precautions regarding mobile AMR genes that may compromise safety.