Inactivation of on post-harvest cantaloupe and lettuce by a lytic bacteriophage cocktail.
Journal:
Current research in food science
Published Date:
Nov 28, 2019
Abstract
() is a causative agent of multiple outbreaks of foodborne illness associated with fresh produce, including pre-cut melon and leafy vegetables. Current industrial antimicrobial interventions have been shown to reduce microbial populations by <90%. Consequently, bacteriophages have been suggested as an alternative to chemical sanitizers. Seven strains from four serovars (10 CFU/mL) were separately inoculated onto excised pieces of Romaine lettuce leaf and cantaloupe flesh treated with a five-strain bacteriophage cocktail 24 h before inoculation. , total aerobic populations and water activity were measured immediately after inoculation and after 1 and 2 days of incubation at 8 °C. The efficacy of the bacteriophage cocktail varied between strains. Populations of Enteritidis strain S3, Javiana S203, Javiana S200 were reduced by > 3 log CFU/g and Newport S2 by 1 log CFU/g on both lettuce and cantaloupe tissues at all sampling times. In contrast, populations of strains Thompson S193 and S194 were reduced by 2 log CFU/g on day 0 on lettuce, but were not significantly different (P > 0.05) from the controls thereafter, Newport S195 populations were reduced on lettuce by 1 log CFU/g on day 0 and no reductions were found on cantaloupe tissue. Both aerobic populations and water activity were higher on cantaloupe than on lettuce. The water activity of lettuce decreased significantly (P < 0.05) from 0.845 ± 0.027 on day 0-0.494 ± 0.022 on day 1, but that of cantaloupe remained between 0.977 and 0.993 from day 0-2. The results of this study showed that bacteriophages can reduce populations on lettuce and cantaloupe tissues but that the magnitude of the effect was strain-dependent.
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