Stress tolerance and characterization of biofilm-like probiotic bacteria encapsulated in calcium pectin beads

Probiotics can regulate gut microbes to maintain human health. However, probiotics are sensitive to environmental conditions, which reduces their survival rates. There are two forms of bacterial cells: single (planktonic) cells and biofilms. Many investigations have verified that biofilm-formed probiotic strains are more resistant to adverse environments than their planktonic counterparts. This study successfully produced high-density probiotic microcapsules in a biofilm state by preparing probiotic cells in biofilm mode and combining them with microencapsulation techniques (>10 log CFU/g). Lactiplantibacillus paraplantarum L-ZS9 was cultured within calcium pectin beads (CPB) to create CPB-Biofilm-situ. Subsequent tolerance experiments revealed that the CPB-Biofilm-situ was highly resistant to acid, the gastrointestinal tract (GIT) environment, and freeze-drying. Furthermore, scanning electron microscopy (SEM) revealed that the cells in CPB-Biofilm-situ displayed a marginalization tendency for the culture. The water content of the beads was approximately 10%, which was deemed acceptable, and the texture characteristics were also determined. The physicochemical properties and structure of the beads were investigated using Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). This work is a valuable reference for a new generation of probiotic agents in the biofilm state.