Gene expression profile of probiotic Lactobacillus casei Zhang during the late stage of milk fermentation

Lactobacillus casei Zhang is a new probiotic strain isolated from koumiss in Inner Mongolia of China, which has been commercially used as starter in the manufacture of dairy products. To study gene expression profile of L. casei Zhang during growth in milk, a whole-genome microarray was used. Compared to L. casei Zhang grown to the late logarithmic phase in milk, 61 genes were significantly up-regulated (>5 fold) in the stationary phase, whereas 26 genes were down-regulated. Collectively, these data showed that the majority of the identified genes were involved in carbohydrate metabolism and energy production, followed by genes involved in nucleotide metabolism, inorganic ion transport, amino acid transport and metabolism, chaperones, etc. This study demonstrates the fundamental effects of cultural conditions on the transcriptome of L. casei Zhang. Moreover, it improves the understanding of growth and survival mechanism of the bacterium during the late stage of milk fermentation.