Genetic mechanisms of prebiotic carbohydrate metabolism in lactic acid bacteria: Emphasis on Lacticaseibacillus casei and Lacticaseibacillus paracasei as flexible, diverse and outstanding prebiotic carbohydrate starters

Lacticaseibacillus casei and Lacticaseibacillus paracasei are widely distributed in various environments, and are common residents of the gastrointestinal tracts of humans and animals. Some Lactic. c asei / Lactic. paracasei strains present remarkably strong capacities of carbohydrate utilization, especially for prebiotics, like fructooligosaccharide, galactooligosaccharide, and human milk oligosaccharide. The ability to metabolize prebiotics and host-derived molecules is beneficial for the survival of probiotic intestinal bacteria in the human gut. This review summarizes the gene regulation mechanisms of carbohydrate utilization in Lactic. c asei / Lactic. paracasei according to the combination both experiments data and genome sequences analysis in order to promote the development of functional products based on these two species . The comparative genomic survey of carbohydrate metabolisms of Lactic. c asei / Lactic. paracasei has been performed in order to reveal the difference among different strains and between two species. The key carbohydrates utilization metabolisms of Lactic. c asei / Lactic. paracasei strains have been summarized and clarified, especially in some prebiotics. Lactic. c asei / Lactic. paracasei strains take flexible and diverse carbohydrates utilization metabolisms. Furthermore, comparative genomic analysis has revealed the carbohydrate uptake and utilization related genes of lactic acid bacteria have species and strains specificity. The cooperation mechanism of different probiotic species and strains will accelerate the development and application of novel probiotics and synbiotics products. In addition, the review provides a reference for the understanding of the complex network regulating carbohydrate metabolisms in other lactic acid bacteria. • Lactic. c asei / paracasei presents strong capacities of prebiotic carbohydrate utilization. • Genetic mechanisms of lactic acid bacteria on metabolism of some prebiotics are clarified. • The comparative genomic survey of carbohydrate metabolisms has been performed. • The prebiotic metabolisms in lactic acid bacteria show species and strains specificity. • The combination of different species and strains is a trend for the development of probiotic products.