Inhibition of Salmonella typhimurium biofilm by commercial disinfectants / Nur Anisah Johari

Salmonellosis is a foodborne disease caused by Salmonella typhimurium; a Gram-negative bacterium that can form biofilm in infected hosts. The effectiveness of existing commercial disinfectants against Salmonella biofilm especially on biomass, viability and biochemical composition of S. typhimurium biofilm needs to be further investigated for biofilm control. The objective of this study was to evaluate the effects of commercial disinfectants against biomass, viability and biochemical composition of S. typhimurium biofilm. S. typhimurium ATCC14028 biofilm was developed in the absence and presence of commercial disinfectants. Sodium hypochlorite, sodium dodecyl-benzene sulfonate, benzalkonium chloride and chloroxylenol-based disinfectants were evaluated in the range between 0.78% and 25%. Biofilm biomass, biofilm viability and biofilm biochemical composition were determined using crystal violet assay, resazurin assay and FTIR-ATR spectroscopy respectively. Results demonstrated that all commercial disinfectants effectively inhibited S. typhimurium biofilm. Treatment with chloroxylenol‐based disinfectant significantly (p<0.05) reduced biofilm biomass and biofilm viability at all tested concentrations. Correlation between biofilm biomass and biofilm viability in the presence of chloroxylenol‐based disinfectant was also found to be significant with r=0.857 and its half-maximal biofilm inhibitory concentration (BIC50) showed the lowest values of 5.06%. Biochemical composition of S. typhimurium biofilm treated with chloroxylenol‐based disinfectant showed changes in FTIR spectral peaks in lipid (1460 cm−1,1400 cm−1) and protein (1550 cm−1,1460 cm−1,1400 cm−1). The findings of the present study suggest that the most efficient agent against S. typhimurium biofilm is a chloroxylenol‐based disinfectant.