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

Abstract

Salmonella 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 Salmonella 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 CyaR, MicC, MicA, InvR, RybB, and DsrA, 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, S. 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 DsrA, MicC, InvR, RybB, MicA, and CyaR. The sRNA RybB, associated with sigma E and outer membrane protein in bacteria, showed a fold change of greater than 7 in S. Enteritidis exposed to the tested stresses. CyaR and InvR involved in general stress responses and stress adaptation were also induced to show high expression levels of Salmonella exposed to hyperosmotic stress. Overall, these findings demonstrated that the behaviors of Salmonella under specific stresses varied according to strain and were likely not related to other profiles. The finding also provided insights into the survival of Salmonella subjected to short-term stresses and for controlling Salmonella in the food industry.

Strain and serovar variants ofSalmonella entericaexhibit diverse tolerance to food chain-related stress

“…Typhimurium strain ST4/74 and DT56. This is a similar finding to a previous study, in which an S. Enteritidis strain showed the smallest decrease in cell number during incubation with salt over a 3-hour period, and could resist the addition of salt concentrations as high as 8% (Wang et al, 2020). The ability for S. Enteritidis to tolerate high salt concentrations poses a potential elevated threat in high-salt foods, such as soy sauce and seafood (Brown et al, 2009).…”

“…This is a similar finding to a previous study, in which an S . Enteritidis strain showed the smallest decrease in cell number during incubation with salt over a 3-hour period, and could resist the addition of salt concentrations as high as 8% (Wang et al , 2020). The ability for S .…”

A Small RNA, SaaS, Promotes Salmonella Pathogenicity by Regulating Invasion, Intracellular Growth, and Virulence Factors

“…Biofilms of S. Enteritidis NCM61 previously demonstrated strong resistance to sanitizer acidic electrolyzed water. Additionally, the planktonic cells displayed strong tolerance to oxidative stress, similar to Salmonella ATCC 13076 with the Enteritidis serotype, particularly the highest tolerance to acidic and hyperosmotic stress in five tested Salmonella strains ( 14 , 49 ). The test strain was stored at −80°C in Luria-Bertani broth (LB; Hope Biotechnology, Beijing, China) containing 60% (vol/vol) glycerol.…”

“…Much pioneering work on sRNA-regulated regions has been done, with the 5′ untranslated region, including the Shine-Dalgarno sequence and the start codon, being shown to be the most essential sequence for base pairing, followed by the coding sequence of the mRNAs ( 8 – 10 ). They have mostly shown significant effects on various cellular processes in bacteria in vitro ( 11 ), particularly sensing and responding to stress conditions, such as DsrA in oxidative stress ( 12 ), CyaR in multiple chemical stresses ( 13 ), and RyhB in acidic environments ( 14 ).…”

An Intertwined Network of Regulation Controls Membrane Permeability Including Drug Influx and Efflux in Enterobacteriaceae

“…Noticeably, sRNAs have a substantial role in regulatory pathways as they regulate and are regulated by ESRs and allow a rapid and efficient response as recently summarized in excellent reviews detailing the mode of regulation and the respective targets [ 88 , 99 , 114 , 115 , 116 , 117 ]. This mechanism of regulation is also important for the balance of energy cost in bacterial cell: by blocking the translation of porins in initial step, it allows substantial energy saving that are required during the production of proteins and their sophisticated assembly in bacterial membrane [ 6 ].…”