Original Research ARTICLE
Characterization of the Desiccation Tolerance of Cronobacter sakazakii Strains
- 1Key Laboratory of Food Nutrition and Safety, Ministry of Education, Tianjin University of Science and Technology, China
- 2Tianjin Key Laboratory of Food Science and Health, School of Medicine, Nankai University, China
Strong desiccation tolerance is an outstanding feature of Cronobacter sakazakii and can enable the bacterium to survive in a dry food matrix (such as milk powder) for a long time. Therefore, contamination of food possessing low water activity with C. sakazakii can increase the risk of infection in human beings, particularly in neonates and infants. However, the mechanism underlying the desiccation tolerance property of C. sakazakii is largely unknown. In this study, the desiccation tolerance characteristics of 42 C. sakazakii strains were analyzed. Simultaneously, the sequence types and biofilm formation abilities of the strains were investigated, and their correlations with desiccation tolerance were analyzed. The results showed no significant correlation between desiccation tolerance and sequence type. However, there was a positive correlation between biofilm formation ability and desiccation tolerance. Raman spectroscopy was employed to investigate the biofilm formed by strains with distinct desiccation tolerance levels, and the results showed that the levels of polysaccharide, proteins and carotenoid might play important roles in the resistance to dry environments. In addition, 10 genes involved in osmoprotectant synthesis or transport were selected, and their differential expression in strains with diverse desiccation tolerance levels was compared to investigate whether these genes were responsible for cytoprotection in the dry environment. The results revealed a great difference in gene expression among strains with different desiccation tolerance levels, suggesting that these genes play a regulatory role in the resistance of C. sakazakii to dry environments. Our study provides a useful reference for follow-up studies investigating the mechanism of desiccation tolerance in C. sakazakii.
Keywords: Cronobacter sakazakii, Multilocus Sequence Typing, desiccation tolerance, Biofilm formation, desiccation tolerance related genes
Received: 28 Aug 2018;
Accepted: 07 Nov 2018.
Edited by:Julio Parra-Flores, University of the Bío Bío, Chile
Reviewed by:Ben D. Tall, United States Food and Drug Administration, United States
Ariadnna Cruz-Córdova, Hospital Infantil de México Federico Gómez, Mexico
Copyright: © 2018 Wang, Du, Wang, Li and Dong. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Prof. Shuo Wang, Tianjin University of Science and Technology, Key Laboratory of Food Nutrition and Safety, Ministry of Education, Tianjin, China, email@example.com