Pseudomonas aeruginosa as a Potential Contaminant of Packed Fresh-Cut Lettuce in a Controlled Atmosphere. The Role of Phenotypes muc+/muc-

: In order to shed light on contamination risks along the ready-to-eat chain of fresh commodities by emerging foodborne pathogens, we investigated the biofilm development in vitro of two Pseudomonas aeruginosa strains on fresh-cut lettuce (Lactuca sativa L. var. Iceberg). The experiment was performed employing a floating bioreactor system where modified atmosphere package conditions were mimicked, and fresh-cut lettuce disks of 2 cm(2) were put into contact with a 10(6) CFU/mL of a phenotypic mucoid P. aeruginosa phenotype (muc(+) ) or a non-mucoid one (muc(-)). Following a simulated 2-day refrigerated-shelf quantitative Real-Time PCR, designed on a target gene region of the 16S rRNA gene, defined the different muc phenotypes behavior on biofilm in lettuce phyllo-plane. Between the two strains, a development difference of nearly 1.0 log CFU/cm(2) occurred, with the muc(+) phenotype being the most settled and adherent. This result clearly showed a distinct contamination risk according to P. aeruginosa phenotype and the need to develop real-time, specific, fast, and easy to use detection protocols along with specific sanitation systems for modified atmosphere package ready-toeat commodities

Automated summary

The study investigated biofilm development of two Pseudomonas aeruginosa strains on fresh-cut lettuce, revealing a significant difference between mucoid and non-mucoid phenotypes. The results emphasized the need for developing specific detection methods and sanitation systems for modified atmosphere package ready-to-eat commodities based on the contamination risk posed by different P. aeruginosa phenotypes.