Detection and Gene Expression of Selected Heat Shock Genes of Cronobacter Sakazakii from Milk and Milk Products

Abstract

Cronobacter sakazakii, is an emerging foodborne pathogen. It can cause necrotizing enterocolitis, bacteremia and meningitis, predominantly in neonates. The present study was conducted to isolate C. sakazakii from dairy products. In the present study total 500 samples of milk and milk products were analyzed in summer, monsoon and winter season from Agra region. Out of these 22 isolates (10 from buffalo milk, 08 from condensed milk, 01 from cow milk and 03 from samples of processed sweets) were selected on the basis of growth pattern on different media. All these samples were further screened on the basis of gram s staining and biochemical test. The positive isolates were further confirmed by molecular identification with PCR using ompA gene and 16s rRNA gene specific primers. Five isolates were sequenced. Their accession numbers are KY977520, KY977521, KY977522, KY977523, and KY982898.The confirmed isolates were further tested for pathogenicity (hemolytic activity) All the isolates were found to be pathogenic. The current study was designed to investigate the growth or survival of a number of natural isolates of C. sakazakii under various stresses: acid Stress, alkaline stress, heat stress, cold stress and desiccation stress. The whole cell protein profiling was done under above mentioned stress conditions. The expression study was analyzed in terms of mean fold change in the stressed bacteria in comparison with unstressed bacteria taken as calibrators Furthermore, analyses of groEL gene were performed in order to examine its expression under various stress conditions among C. sakazakii strains. In the present study the impact of stress: acid, alkaline, heat, cold and desiccation on antibiotic susceptibility of C. sakazakii were analyzed. A total of twenty four antibiotics were used and varied antibiotic susceptibility was observed in this study. Antagonistic activity of LAB was determined against stressed and unstressed C. sakazakii by the agar well diffusion method. L. fermentum was found to have the highest ant