Biofilm formation by pGFPuv labeled mutant Cronobacter sakazakii in the absence and presence of other bacteria

Abstract

Cronobacter sakazakii has been reported to form biofilm on food contact surfaces thus could be a potential source of contamination in food industries. This study aimed to investigate biofilm formation by pGFPuv labeled C. sakazakii local strains on stainless steel (SS), Buna-N rubber (Buna-N) and polytetrafluorethylene (PTFE) surfaces at various incubation times and compare biofilm formation by C. sakazakii pGFPuv on SS in the presence and absence of Staphylococcus aureus and Lactobacillus rhamnosus. Two pGFPuv labeled C. sakazakii isolates were inoculated separately into broth medium containing SS, Buna-N or PTFE coupons and incubated for 24, 48 and 72 hrs at room temperature. Formation of biofilm by these isolates was also investigated on SS in the presence of S. aureus and L. rhamnosus. The biofilm density was enumerated by swabbing followed by plating. The results showed that pGFPuv labeled mutants formed biofilms (up to 5 Log CFU/cm2 ) on all food contact surfaces. The highest biofilm density was found on PTFE while the lowest was on Buna-N surfaces. The biofilm density of C. sakazakii pGFPuv on SS was similar irrespective of the presence or absence of S. aureus and L. rhamnosus. This study corroborates the ability of C. sakazakii to form biofilms on food contact surfaces and provides evidence that the density of the biofilm is not affected by the presence of S. aureus and L. rhamnosus.