Phenotypic Traits and Probiotic Functions of Lactiplantibacillus plantarum Y42 in Planktonic and Biofilm Forms

Abstract

Bacteria in planktonic and biofilm forms exhibit different phenotypic properties. In this study, the phenotypic traits and probiotic functions of Lactiplantibacillus plantarum Y42 in planktonic and biofilm forms were assessed. After 36 h of static culture, scanning electron microscopy and confocal laser scanning microscopy showed that the L. plantarum Y42 bacterial cells contained interconnected adhesive matter on the surface, forming a ~18 μm layer of dense biofilms. The surface properties of L. plantarum Y42 in biofilm form, including autoaggregation ability, hydrophobicity, acid-base charge, and adhesiveness, were all higher than those in the planktonic form. Biofilm L. plantarum Y42 showed a higher tolerance to adverse environmental conditions and a higher survival rate, enzymatic activity, and integrity after vacuum lyophilization. And biofilm L. plantarum Y42 had higher adhesion to human enterocyte HT-29 cell monolayers, inhibited the expressions of proinflammatory factors IL-6 and TNF-α, and promoted the expressions of the anti-inflammatory factor IL-10 and barrier proteins Claudin-1 and Occludin. In addition, L. plantarum Y42 in biofilm form can inhibit the adhesion and invasion of Listeria monocytogenes ATCC 19115 to HT-29 cell monolayers and is more effective in relieving the inflammatory reactions and injuries of HT-29 cells caused by L. monocytogenes ATCC 19115. In conclusion, L. plantarum Y42 in biofilm form exhibited better probiotic functions compared to that in planktonic form. This indicated that L. plantarum Y42 can form biofilms to enhance its probiotic functions, which provided a theoretical basis for better development and utilization of L. plantarum Y42.

Exopolysaccharides and Surface-Layer Proteins Expressed by Biofilm-State Lactiplantibacillus plantarum Y42 Play Crucial Role in Preventing Intestinal Barrier and Immunity Dysfunction of Balb/C Mice Infected by Listeria monocytogenes ATCC 19115

“…Among them, the live biofilm L. plantarum Y42 significantly outperformed the live planktonic cells in downregulating IL-1β and TNF-α and upregulating IL-10 and IgA ( p < 0.05), which is consistent with our previous in vitro cell experiments …”

“…Among them, the live biofilm L. plantarum Y42 significantly outperformed the live planktonic cells in downregulating IL-1β and TNF-α and upregulating IL-10 and IgA (p < 0.05), which is consistent with our previous in vitro cell experiments. 25 Furthermore, pasteurized planktonic and biofilm L. plantarum Y42 still showed a similar regulating effect, and the regulatory effect of pasteurized biofilm L. plantarum Y42 was significantly stronger than that of pasteurized planktonic cells (p < 0.05). And the differential metabolites (exopolysaccharides and surface-layer proteins) had a good regulatory effect on the inflammatory response and immune function of the mice.…”