Differential effects of growth medium salinity on biofilm formation of Salmonella enterica svs. Enteritidis and Newport

Authors: GU, LIHONG - Huazhong Agricultural University; CHEN, QIAN - Huazhong Agricultural University; GUO, AILING - Huazhong Agricultural University; RUAN, YAO - Huazhong Agricultural University; ZHANG, XINSHUAI - Huazhong Agricultural University; Nou, Xiangwu

Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/8/2019
Publication Date: 1/2/2020
Citation: Gu, L., Chen, Q., Guo, A., Ruan, Y., Zhang, X., Nou, X. 2020. Differential effects of growth medium salinity on biofilm formation of Salmonella enterica svs. Enteritidis and Newport. Journal of Food Protection. 83(2):196-203. https://doi.org/10.4315/0362-028X.JFP-19-418.
DOI: https://doi.org/10.4315/0362-028X.JFP-19-418

Interpretive Summary: This study showed that salt in growth medium differently affected the biofilm formation by different serotypes of Salmonella strains. while low concentration of salt slighted increased biofilm for Salmonella serotype Enteritidis, it sharply reduced or abolished biofilm formation of Salmonella serotype Newport. It was further demonstrated that this difference was most likely due to the differences in impacting bacterial cell motility, and expression of motility related genes. The information generated in this study is useful for understanding Salmonella biofilm formation and for biofilm elimination.

Technical Abstract: Salmonella enterica is a prominent food-borne pathogen, including diverse serotypes that are prolific biofilm formers. The ability of bacterial biofilm formation can be affected by multiple environmental factors. In this study, the effect of salinity on biofilm formation by S. enterica was evaluated using two recently isolated strains of serotypes Enteritidis and Newport. While supplementing the growth medium with low concentration (0.5-2%) of NaCl slightly enhanced biofilm formation for the strain S. enterica sv. Enteritidis 110 (S. Enteritidis 110), it sharply reduced or abolished biofilm formation by the strain S. enterica sv. Newport 193 (S. Newport 193). This differential effect of salinity on S. enterica strains of different serotypes was poorly correlated to inhibition of planktonic growth, but strongly correlated to cell motility. Examining genes known to affect biofilm formation showed that the expression of adrA, csgD, and fliC, which encode proteins required for surface adhesion and cell motility, was significantly down-regulated with salinity increase in S. Newport 193, whereas not in S. Enteritidis 110. Therefore, it is plausible that the differential effect of salinity on biofilm formation by S. Enteritidis 110 and S. Newport 193 resulted from the differential regulation to genes required for cell adherence and motility.