Lactobacillus casei asp23 gene contributes to gentamycin resistance via regulating specific membrane-associated proteins.

Lactobacillus casei Zhang is a probiotic strain originally isolated from koumiss. Previously, we showed that an alkaline shock protein (encoded by asp23) was involved in the adaptation of L. casei Zhang to gentamycin. In the present study, we compared the proteomes of the asp23 mutant and its parent strain grown in the presence of gentamycin. The results showed that 22 and 21 proteins were significantly up- and downregulated, respectively (>1.5-fold difference). By parallel reaction monitoring analysis, we further validated that specific membrane-associated proteins were important in regulating the antibiotics-induced cell wall stress. The findings provide insight into the physiological role of the asp23 gene in the growth response of L. casei when exposed to antibiotic stress.