Proteome analysis of Lactobacillus plantarum strain under cheese-like conditions

As a food grade fermentation starter, Lactobacillus plantarum (L. plantarum) also named as the secondary starters during cheese ripening. In this study, the concentration of NaCl was screened as the main factor in the cheese-like conditions (15°C, pH5.2, 6% NaCl) to assess the potential properties of L. plantarum. A comprehensive proteome profile of L. plantarum strain was analyzed with iTRAQ proteomics methods fractionated by SCX chromatography. Proteins involved in carbohydrate transport and metabolism, cell envelope, peptide-glycan biosynthesis and lipid transport and metabolism were found significant changes. Meanwhile, the same trends were found in mRNA expression levels analyzed by RT-PCR. Some general transportation proteins related to ion transporters were detected as more abundant, which may reveal a rescue mechanism of the microbe in sodium-dependent glucose transfer. The understanding of L. plantarum proteome in salt tolerance could be useful to get strain adapted for specific applications.

The bacterial biota has a primary role in affecting cheese quality. Under cheese-like conditions, L. plantarum mainly increased the levels of enzymes that responsible for the flavour development during cheese ripening. However, the mechanisms of proteomic adaptation remain largely unclear in unraveling details of the salt tolerance of L. plantarum. This study revealed a dramatic change involved in carbohydrate transport and metabolism, cell envelope, peptide-glycan biosynthesis, lipid transport and metabolism, and glycolysis. Meanwhile, these pathways provide a comprehensive proteome profile of L. plantarum survived under cheese-like conditions. Furthermore, this study shows that iTRAQ proteomics provide more reliable information in describing the molecular rescue strategy of L. plantarum in sodium-dependent glucose transfer.