Microencapsulation is an up-and-coming technology for maintaining the viability of probiotics. However, the effect of core-to-wall ratios and ratios of polysaccharides on the protection of the Lactiplantibacillus plantarum 299v strain has not been deeply discussed. Lyophilization of the Lp. plantarum 299v strain was conducted, and different core-to-wall ratios and ratios of maltodextrin (MD) and resistant starch (RS) were applied. Results demonstrated that the content of MD and RS had an influence on the yield and bulk density in both core-to-wall ratios (1:1 and 1:1.5). In addition, samples coated with a core-to-wall ratio of 1:1.5 had significantly higher viability than those coated with a core-to-wall ratio of 1:1. Moreover, samples coated with core-to-wall ratios of 1:1 and MD:RS 1:1, as well as core-to-wall ratios of 1:1.5 and MD:RS 3:1, had the highest cell number after simulated gastric fluid and simulated intestinal fluid testing, respectively. Furthermore, the optimal formulation for the application of microencapsulated Lp. plantarum 299v in apple juice (serving as a functional beverage) is listed as follows: core-to-wall ratios of 1:1 and MD:RS 1:1, with the fortification method, and stored at 4 °C. After 11 weeks of storage, the cell count was 8.28 log (CFU/mL). This study provided a strategy for Lp. plantarum 299v to achieve high viability in long-term storage and provides an application in functional apple beverages.

Lactic acid bacteria exhibit high adaptability to their environment due to their wide variety of enzymes. Despite extensive knowledge of bacterial cell walls, the subcellular localization of β-galactosidase in many probiotic lactic acid bacteria, including Limosilactobacillus fermentum, remains unclear. Determining the cellular localization of such enzymes may improve insight into bacterial metabolic mechanisms and support the development of efficient downstream processes, as well as applications. In this study, three cell disruption strategies (mechanical homogenization and chemical disruption with different agents) were applied to assess the subcellular localization of β-galactosidase from the Ll. fermentum LF08 strain. Enzyme activity was measured in a ferment broth, a supernatant and cell-associated fractions. No and very low β-galactosidase activity was detected in the ferment broth and the supernatant, respectively, when either chemical or mechanical treatment was applied, whereas the main enzyme activity was assayed in the cell suspension fraction. Combined lysozyme and CTAB treatment resulted in a 21.4-fold increase in β-galactosidase activity in the supernatant fraction (2.14 U/mL), compared with CTAB treatment alone (0.10 U/mL). Bioinformatic analyses provided additional significant information to propose the potential cell wall association (maybe the outer side of the cell wall) of the subcellular localization of β-galactosidase. This feature may support understanding of the interactions between probiotic bacteria and host tissues, as well as the development of probiotic immobilized cell systems for applications such as the elimination of lactose, designing novel functional foods.