Submitted to: Journal of Food Protection
Publication Type: Peer reviewed journal
Publication Acceptance Date: 1/11/2013
Publication Date: 5/1/2013
Citation: Liu, N., Lefcourt, A.M., Nou, X.A., Shelton, D.R., Zhang, G., Lo, Y. 2013. Native microflora in fresh-cut processing plants and their potentials of biofilm formation. Journal of Food Protection. 76(5):827-832. Interpretive Summary: Previous research indicates that biofilms are particularly difficult to sanitize and that pathogenic bacteria may become incorporated into biofilms. In this study, bacterial strains were isolated from various types of surfaces in two local fresh-cut produces processing plants after routine sanitization in order to identify bacteria typically associated with fresh produce processing environment. The ability of these strains to form biofilms on solid substrates was evaluated in the laboratory. Bacteria with strong biofilm formation capacities, such as Rostonia insidiosa, were highly prevalent, underlining the potential risk of biofilm formation on these surfaces. This information should be useful to the fresh produce processing industry.
Technical Abstract: Representative food contact and non-food contact surfaces in two mid-sized fresh cut processing facilities were sampled for microbiological analyses post routine daily sanitization. Mesophilic and psychrotrophic bacteria on the sampled surfaces were isolated by plating on non-selective bacterial media. Alternatively, bacteria were isolated following an incubation period which allowed the formation of heterogeneous biofilms on stainless steel beads. For over 1000 tested isolates, most were capable of forming biofilms, with approximately 30% being strong or moderate biofilm formers. Selected isolates (120) were subjected to species identification using Biolog GenIII system. They distributed among 23 genera, which included soil bacteria, plant related bacteria, coliforms, and opportunistic plant or human pathogenic bacteria. The most commonly identified bacteria species were Pseudomonas fluorescens, Rahnella aquatilis and Ralstonia insidiosa. The high prevalence of R. insidiosa, a strong biofilm former, and P. fluorescens, a moderate biofilm former, suggests that they were established residents in the sampled plants. This work suggests that resident microflora capable of forming biofilms are widely distributed in fresh produce processing environments.