Study of effect of hydroetanolic extracts thyme, licorice and garlic on biofilm formation of Escherichia coli, Staphylococcus aureus, Bacillus cereus in foodstuff

Rezvan Pouya, Adeleh Sobhanipour, Abalghasem Rahbari, Seyed Taghavi, Javad Momeni
2016 Scinzer Journal of Agricultural and Biological Sciences   unpublished
Biofilms (biolayers) are associations of living bacterial cells that adhere to various surfaces. Formation of biofilms composed of microorganisms on food materials (and surfaces in contact with them) exacerbates health-related problems and economic losses that result from decaying of food materials. Staphylococci, Bacilli, and Escherichia are among the most common bacteria that contaminate foodstuffs. This research studied the effects of thyme, licorice, and garlic extracts on reducing biofilms
more » ... of these bacteria in a laboratory environment. The method of measuring light absorption by the biofilms in the wells of 96-well plates was used, and results showed the mentioned extracts had antimicrobial properties and reduced biofilm formation by Staphylococcus aureus, Escherichia coli, and Bacillus cereus. Increasing the concentrations of the extracts improved their inhibitory effects (by up to 71 and 64% against E. coli and B. cereus, respectively), but the maximum inhibitory effect on S. aureus was that of the lowest concentration of thyme extracts. Increasing the concentration of garlic extracts improved their inhibitory effects. Moreover, the inhibitory effects of licorice extracts on biofilm formation by Bacillus cereus and Escerichia coli exhibited an ascending trend, but the maximum inhibitory effect on biofilm formation by Staphylococcus aureus was observed at the lowest extraction concentration (0.25). The differences between the inhibitory effects of the three types of extracts on these microorganisms were significant (p<0.05), but the differences between their concentrations were not (p>0.05).