Sucrose improve Lactiplantibacillus plantarum LIP-1's tolerance to heat by increasing biofilm production

Optimizing the carbon source to increase biofilm production and thus boost the heat tolerance of strains is a promising strategy. However, related research is scarce. This study investigated the effects of varying glucose and sucrose amounts added to MRS medium on biofilm production and heat tolerance by Lactiplantibacillus plantarum LIP-1. Transcriptomic, proteomic, and metabolomic approaches were combined to analyze the intrinsic mechanism underlying the sucrose-induced increase in biofilm production. We then investigated the protective role of the biofilm for the strain.

Compared with the control group (2 % glucose), biofilm production in the experimental group (2 % glucose+2 % sucrose) increased by 27 %, and after heat treatment (75 °C for 40 s), the experimental group demonstrated a 38 % increase in heat tolerance. Multiomic results unveiled that biofilm synthesis-related metabolism pathways were altered in the experimental group compared with the control group. When the expression of key genes and the enzymes they encode(sacA, metC, mccB, and CTH) was upregulated, L-homocysteine was synthesized. According to metabolomics results, the L-homocysteine content in the experimental group increased to twice that in the control group. This resulted in a 37 % increase in the extracellular protein content of biofilms. The biofilm inhibition test confirmed that this increase in extracellular protein content was the primary factor augmenting the strain's heat tolerance.

The findings suggested that adding sucrose to MRS medium for boosting biofilm production is a viable technical approach that enhances cell tolerance to heat.