Gene expression of Lactobacillus plantarum FS5-5 in response to salt stress

Lactobacillus plantarum FS5-5—a new isolate from agricultural soybean paste—shows good growth in an environment with 12 % (w/v) NaCl. To understand the potential relationship between regulatory systems and its growth under different salt concentrations, the expression of genes encoding enzymes involved in five regulatory systems was determined by quantitative real-time polymerase chain reaction (qPCR). The results showed that the optimal growth of this strain relied on the cooperative action of different regulatory systems, with each system playing an important role in L. plantarum FS5-5 in adapting to salt stress. Interestingly, most of the genes showed higher expression under higher concentrations of NaCl, suggesting that L. plantarum FS5-5 uses its regulatory systems preferentially to sustain its growth. In addition, the expression change of a gene encoding glyceraldehyde-3-phosphate dehydrogenase (gapB) was not significant under different salt concentrations, indicating that it may be used as a housekeeping gene in the qPCR experiment on L. plantarum after exposure to salt stress. This study provided a global view of the effect of NaCl on the ability of L. plantarum FS5-5 to resist salt stress and may help us to develop strategies to improve the robustness of industrial production.