Sub-lethal Heat Treatment Effects Protein Expression and Fatty Acid Profile of Cronobacter sakazakii

• Main Authors: Po-Ting Li, 黎柏廷
• Other Authors: 周正俊
• Format: Others
• Language: zh-TW
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/81223685692896545800

碩士 === 國立臺灣大學 === 食品科技研究所 === 98 === Cronobacter sakazakii is a Gram-negative, emerging opportunistic pathogen which has been associated with life-threatening cases in infants, with infant formulas been implicated as the mode of transmission, and with high mortality rate of 40-80%. In the present study, C. sakazakii BCRC 13988, the type strain, was subjected to heat shock treatments (47℃, 15 min). The effect of heat shock on the protein expression, fatty acid profile as well as growth and survival behavior of heat-shocked C. sakazakii in the milk containing copper ion were examined. Analysis with one-dimensional SDS-PAGE showed that expression of 11 proteins bands was enhanced while 1 protein was reduced in the heat-shocked cells of C. sakazakii compared with control cells. The protein patterns revealed by two-dimensional electrophoresis showed that heat shock treatment affected the expression of 25 proteins, the levels of 16 proteins increased and 9 proteins decreased. Four proteins with enhanced expression level were subjected to tryptic digestion, LC/MS/MS analysis and protein identification using database search. They were identified as chaperone IbpB, OmpA, OmpX and FoF1 ATP synthase subunit α. IbpB exhibited protection effect in thermal environment. OmpA and OmpX involved in cellular osmotic pressure regulation, bacterial adhesion, or biofilm formation. FoF1 ATP synthase subunit α was related to energetic production. These proteins may not only correlate closely with the higher tolerance of C. sakazakii under various stress conditions but also involve in some other physiological regulation. It was also noted that heat shock significantly enhanced (p<0.05) the ratio of saturated fatty acids to unsaturated fatty acids in the cells of C. sakazakii. Besides, heat shock also enhanced the survival of C. sakazakii in sterile milk containing 100 μg ml-1 copper ion.