Molecular mechanism of increasing extracellular polysaccharide production of Paenibacillus mucilaginosus K02 by adding mineral powders

Bacterial polysaccharides are widely applied in a range of products and increasing bacterial polysaccharide production is important commercially. In this study, attapulgite, serpentine, talc, biotite, and hydroxylapatite were used to stimulate extracellular polysaccharide (EPS) production by Paenibacillus mucilaginosus K02. The viscosity, polysaccharides, and proteins in culture medium in shaking flasks were quantified after addition of different minerals to the culture medium, and the molecular mechanism of serpentine on stimulating bacterial EPS synthesis was further revealed by proteomic and metabolomic analysis. The results showed that the viscosity, EPS, and protein contents in the culture were significantly increased by the introduction of minerals. The underlying mechanism for increased EPS production was due to a series of protective strategies of the bacterium against the damage arising from collision and friction caused by mineral powders. That is, bacteria protect and maintain their normal life by synthesis and secretion of excessive EPS, enhancement of oxidation resistance and secretion of various organic acids under these mineral treatments. The results not only show the importance of polysaccharide production for bacteria survival under adverse conditions, but also provide a new way of increasing bacterial production of more EPSs.