Proteomic analysis of lactose-starved Lactobacillus casei during stationary growth phase.

摘要

Starvation stress is a condition that nonstarter lactic acid bacteria (NSLAB) encounter, for example during cheese ripening. This study investigated starvation-induced proteins in Lactobacillus casei during the stationary growth phase. The impact of carbohydrate starvation on L. casei GCRL163 was investigated using 2 different media (a modified MRS broth and a semi-defined medium). Cells were grown in the presence of excess lactose (1%) or starvation (0%) and differences in the patterns of 1D SDS-PAGE electrophoresis and 2-dimensional electrophoresis of the cytosolic protein fractions were investigated. Differentially regulated proteins were identified by MALDI-TOF/TOF MS. Many differentially regulated proteins were enzymes of various metabolic pathways involved in carbohydrate metabolism to yield energy. Differences in protein expression were also observed in the 2 culture conditions tested in this experiment. In conclusion, numerous glycolytic enzymes were differentially regulated under lactose starvation. The differential expression of these glycolytic enzymes suggests a potential survival strategy under harsh growth conditions (i.e. lactose starvation).