Antimicrobial effect of carvacrol on Escherichia coli K12 growth at different temperatures

A study was carried out to evaluate the antimicrobial activity of carvacrol on Escherichia coli K12 (CECT 433) at different incubation temperatures (30 and 37 degrees C). Regardless of the temperature, both the maximum specific growth rate (mu(max)) and the lag phase (lambda) showed to be dependent on the carvacrol concentration but in different ways. While lambda was directly proportional to the antimicrobial concentration, mu(max) showed to be inversely proportional to it, being 0.14 mu l ml(-1) a lethal concentration, and existing a log-linear relationship between that parameter and the tested concentrations (R >= 0.900). Comparing the results for both temperatures for each concentration, no significant differences were detected in mu(max) but lambda is always longer at 30 degrees C than at 37 degrees C value <= 0.05). These results indicate that carvacrol is active against E. coli K12 growth, so it could be used to extend the shelf life and improve the safety margins of minimally processed foods.