Lactobacillus plantarum NCU001774 microcapsules target and inhibit cariogenic Streptococcus mutans

This study aims to develop a cariogenic bacteria-targeting delivery system to release lactobacilli at infectious sites. Firstly, L. plantarum NCU001774 was selected as anti-S. mutans strain from 385 lactic acid bacteria by evaluating its inhibitory effects on S. mutans, tolerance to lysozyme, and protective effect on hydroxyapatite. Subsequently, NCU001774 microcapsules composed of gelatin/chitosan in a ratio of 1:5 (2%, W/V), trehalose as protectant (2%, W/V), were successfully prepared. The NCU001774 microcapsules were mainly 1–5 μm, with the t1/2 of 12.01 min at pH4.5 and 21.41 min at pH7.2. When the environmental pHwasbelow6.5, NCU001774 microcapsules were positively charged, which enabled the targeting effect on S. mutans biofilm through electrostatic interaction. Fluorescence staining and scanning electronic microscopy assay further confirmed the targeting effect of NCU001774 on the surface of S. mutans biofilm. The formation of S. mutans biofilm was reduced by 62% with the treatment of NCU001774 microcapsules. Meanwhile, the number of S. mutans decreased by NCU001774 microcapsules from 8.50 to 2.20 (lgCFU/mL) at 24 h. The microcapsules developed in this study can release lactobacilli at targeted infectious sites and inhibit growth and biofilm formation of S. mutans, demonstrating great potential in prevention of S. mutans associated infection including dental caries.