Plant extracts effective against biofilm formation of Salmonella and Enterococcus pathogens relevant to the poultry industry

Salmonella and Enterococcus species are important foodborne pathogens in the poultry industry. Due to their persistent biofilm forming properties, simple strategies such as cleaning and sanitisation of surfaces in poultry processing are not entirely effective. In this study we examined the antibacterial and anti-biofilm activity of acetone and methanol plant extracts of sixteen South African plants preliminarily identified for their antibacterial activity. The minimum inhibitory concentration (MIC) against Salmonella enterica subsp. enterica serovar Typhimurium (ATCC 700720) and Enterococcus faecalis (ATCC 29212) was determined using a serial microdilution assay. Extracts were screened for cellular toxicity against Vero mammalian cells. The ability of the plant extracts at a sub-inhibitory concentration of 0.156 mg/ml to prevent biofilm formation was assessed using the crystal violet quantification method. The crude extracts had MIC values ranging from

0.313 to 2.5 mg/ml. Relatively low cytotoxicity was observed with selectivity index values of 2.21 and 1.39 against S. Typhimurium and E. faecalis respectively. The methanol extract of Senegalia galpinii inhibited 85.20% of S. Typhimurium and 97.27% of E. faecalis cell attachment after 24 h incubation, indicating anti- biofilm activity. Such bioactive plant extracts may be suggested for further development into antimicrobial and antibiofilm natural products to be used in the poultry industry. Future studies include exploring mechanism of action and isolation of active compounds.

 

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Conflict of Interest

The authors declare no conflict of interest.

Publication History

Article published online:
16 November 2023