AUTHOR=Wang Huhu , Huang Mingyuan , Zeng Xianming , Peng Bing , Xu Xinglian , Zhou Guanghong 

TITLE=Resistance Profiles of Salmonella Isolates Exposed to Stresses and the Expression of Small Non-coding RNAs

JOURNAL=Frontiers in Microbiology

VOLUME=11

YEAR=2020

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2020.00130

DOI=10.3389/fmicb.2020.00130

ISSN=1664-302X

ABSTRACT=<p><italic>Salmonella</italic> can resist various stresses and survive during food processing, storage, and distribution, resulting in potential health risks to consumers. Therefore, evaluation of bacterial survival profiles under various environmental stresses is necessary. In this study, the resistance profiles of five <italic>Salmonella</italic> isolates [serotypes with Agona, Infantis, Typhimurium, Enteritidis, and a standard strain (ATCC 13076, Enteritidis serotype)] to acidic, hyperosmotic, and oxidative stresses were examined, and the relative expressions of non-coding small RNAs were also evaluated, including <italic>CyaR</italic>, <italic>MicC</italic>, <italic>MicA</italic>, <italic>InvR</italic>, <italic>RybB</italic>, and <italic>DsrA</italic>, induced by specific stresses. The results indicated that although all tested strains displayed a certain resistance to stresses, there was great diversity in stress resistance among the strains. According to the reduction numbers of cells exposed to stress for 3 h, <italic>S.</italic> Enteritidis showed the highest resistance to acidic and hyperosmotic stresses, whereas ATCC 13076 showed the greatest resistance to oxidative stress, with less than 0.1 Log CFU/ml of cell reduction. Greater resistance of cells to acidic, hyperosmotic, and oxidative stresses was observed within 1 h, after 2 h, and from 1 to 2 h, respectively. The relative expression of sRNAs depended on the isolate for each stress; acidic exposure for the tested isolates induced high expression levels of <italic>DsrA</italic>, <italic>MicC</italic>, <italic>InvR</italic>, <italic>RybB</italic>, <italic>MicA</italic>, and <italic>CyaR</italic>. The sRNA <italic>RybB</italic>, associated with sigma E and outer membrane protein in bacteria, showed a fold change of greater than 7 in <italic>S.</italic> Enteritidis exposed to the tested stresses. <italic>CyaR</italic> and <italic>InvR</italic> involved in general stress responses and stress adaptation were also induced to show high expression levels of <italic>Salmonella</italic> exposed to hyperosmotic stress. Overall, these findings demonstrated that the behaviors of <italic>Salmonella</italic> under specific stresses varied according to strain and were likely not related to other profiles. The finding also provided insights into the survival of <italic>Salmonella</italic> subjected to short-term stresses and for controlling <italic>Salmonella</italic> in the food industry.</p>