Lactose starvation response of Lactobacillus casei strain GCRL163

The continuing augmentations of interest in Lactic Acid Bacteria (LAB) have led to an increase in manufactured functional foods. Given the intestinal origin of these microorganisms, the challenges these sensitive bacteria face in order to be in a highly viable state throughout processing and storage. One of these challenges is surviving in carbohydrate depleting in chess maturation. In this study, starved Lactobacillus casei strain GCRL163 originally isolated from Australian Cheddar cheese was used to investigate the physiology of slow growth and characterise the protein expression in lactose starvation. Proteomics of L. casei strain GCRL 163 were studied to clarify the physiological changes occurring during growth in modified MRS (mMRS) with different levels of lactose (0% no lactose starvation, 0.2% limiting growth, and 1% no growth limiting). One-dimensional sodium dodecyl sulfate polyacrylamide gel electrophoresis (1D SDS-PAGE) and one-dimensional liquid chromatography mass spectrometry (1D LC/MS) were used as analysis methods. The tested strain shows the ability to survive better in lactose free mMRS compared with other treatments. Changes in SDS-PAGE patterns of cells grown in different lactose levels were range of down-regulated proteins and some of up-regulation proteins in starved cells also observed, and preliminary results of 1D LC/MS will be discussed. These results will help to characterise the mechanisms by which Lactobacillus function as beneficial dietary adjunct and how the external environments influences the expression of factors that impact on probiotic function.