Characterization of attachment and biofilm formation by meat-borne Enterobacteriaceae strains associated with spoilage

- Great variations in hydrophobicity and motility were found among tested strains.
- More than 4.5 log CFU/cm2 cells were transferred under a short-term (5 h) scenario.
- E. cloacae showed great biofilm formation under a long-term (7 d) scenario.
- A complex three-dimensional structure of mature biofilm was observed by CLSM.
- Polysaccharides were found in mature biofilm.

Meat wastes and losses were associated with spoilage microorganisms, usually sourcing from the biofilm cross-contamination. In this study, the attachment and biofilm formation of five meat-borne Enterobacteriaceae strains (Enterobacter cloacae, Hafnia alvei, Proteus mirabilis, Citrobacter freundii and Klebsiella oxytoca) were characterized by two simulated contamination scenarios. There were great variations in surface hydrophobicity, motility and adhesion ability on a polystyrene surface of 96-well microplates among these tested strains. P. mirabilis and C. freundii showed higher adhesion than other strains. More than 4.5 log CFU/cm2 cells were transferred to stainless steel surface under a short-term (5 h) attachment scenario. More than 8 log CFU/cm2 of biofilm formation on stainless steel surface under a long-term (7 d) growth scenario were found for all tested strains, and nearly 10.5 log CFU/cm2 cells were observed for E. cloacae after 5-day incubation. A mature biofilm architecture was observed by confocal laser scanning microscopy (CLSM), consisting of multilayer aggregates of more than 30 μm thicknesses. This was further confirmed by attenuated total reflectance fourier transform infrared spectroscopy (ATR-FTIR), and the dominant peaks in biofilm spectra were mainly associated with amide, polysaccharides and glycosidic linkage. This finding could provide the basic data for developing novel disinfectant strategies.