Yeast cell wall polysaccharides in Tibetan kefir grains are key substances promoting the formation of bacterial biofilm

This study investigated the interaction among Kluyveromyces marxianus G-Y4 (G-Y4), Lacticaseibacillus paracasei GL1 (GL1) and Lactobacillus helveticus SNA12 (SNA12) that isolated from Tibetan kefir grains. Additionally, the effects of G-Y4 on the growth and biofilm formation of GL1 and SNA12 were determined. The results indicated that G-Y4 promoted the growth of GL1 and SNA12 and improved their biofilm-forming ability. Furthermore, the dead cells of G-Y4 were found that could enhance bacterial biofilm formation, and the cell wall polysaccharide (CWPS) produced by G-Y4 was performed to be key substances that promote the formation of bacterial biofilms. Moreover, the structure of soluble cell wall polysaccharides (SCWP) and insoluble cell wall polysaccharide (NCWP) of G-Y4 were studied to determine their contribution to biofilm formation. Results showed that G-Y4-SCWP was alpha-mannan with the main chain of a -> 6)-alpha-D-Manp-(1 -> unit and the branch structure of -> 2)-alpha-D- Manp-(1. At the same time, G-Y4-NCWP was a glucan rich in beta-(1 -> 3), beta-(1 -> 2), or beta-(1 -> 4) linkages.