Growth potential and biofilm development of nonstarter bacteria on surfaces exposed to a continuous whey stream

Commercial Cheddar cheese production uses an automated, continuous system that provides favorable conditions for specific undesirable bacterial subpopulations in certain sections of the processing system. The draining and matting conveyor (DMC) is a large, fully enclosed series belts separates curd whey on first drain belt supports cheddaring process subsequent sections. In previous study, we demonstrated coliforms increase section DMC (pH 6.0–6.3, 36°C) over typical 18-h shift can lead to detectable finished cheese. Sampling at commercial plant indicated 2 sources very low levels coliforms: (1) subpasteurized entering (2) surfaces after sanitation. Mitigation these would require different approaches. aim this study was investigate whether naturally could bulk liquid attach surface materials within 18 h. A laboratory-scale created mimic initial consisted single-pass, contaminated 6.3, 35°C) flowing through bioreactor (1.11 L/h) containing coupons types found (stainless steel polypropylene). Whey inside chamber were enumerated selective media planktonic attached bacteria, respectively, 0, 12, 15, Bacterial isolates identified by 16S rDNA sequencing. Nonstarter bacteria present 0 h included (Enterobacter), Pseudomonas, Acinetobacter (0.80, 2.55, 2.32 log cfu/mL, respectively), with each increasing significantly (6.18, 7.00, 5.89 cfu/mL) (5.20, 6.85, 5.29 cfu/cm2, respectively) Scanning electron microscopy confirmed attachment both surfaces, early biofilm development evident polypropylene Results from replicate environment.