Lactiplantibacillus plantarum Y42 in Biofilm and Planktonic States Improves Intestinal Barrier Integrity and Modulates Gut Microbiota of Balb/c Mice

In our previous study, Lactiplantibacillus plantarum Y42 showed some potential probiotic functions and the ability to form biofilm. The aim of this study was to compare the similarities and differences in the probiotic and physiological traits of L. plantarum Y42 in the biofilm and planktonic states. L. plantarum Y42 in the biofilm state was proven to have higher survival after passing through mimic gastrointestinal fluid, as well as excellent adhesion properties on the HT-29 cell monolayers, than those in the planktonic state. The expression of tight junction proteins (TJ proteins) of HT-29 cell monolayers treated by L. plantarum Y42 in the planktonic state increased, while similar changes were not observed in the HT-29 cells treated by the strain in the biofilm state. Furthermore, Balb/c mice were orally administered L. plantarum Y42 in the biofilm and planktonic states, respectively. Compared to the planktonic state, the oral administration of L. plantarum Y42 in the biofilm state significantly boosted IgA levels and improved the immunity of the mice. High-throughput sequencing showed that the diversity and structure of the intestinal flora of the mice were changed after the oral administration of L. plantarum Y42, including the up-regulated relative abundance of Lactobacillus in the intestinal tract of the mice, with no difference between the biofilm and planktonic states. Moreover, oral administration of L. plantarum Y42 in biofilm and planktonic states reduced the release of proinflammatory factors, to a certain extent, in the serum of the mice. The similarities and differences in the probiotic and physiological properties of L. plantarum Y42 in the biofilm and planktonic states can be contributed to the reasonable application of the strain.