Biofilm formation by meat-borne anti-listerial Lactobacillus strains on industrial surfaces at low temperature

PEREZ IBARRECHE MARIANA; PEÑA NATALIA; CASTELLANO P; VIGNOLO G

Estambul

Congreso; Food Micro Istanbul 2012; 2012

Research on microbial biofilms has been documented in many areas, with particular emphasis on evaluation of various control strategies foreither preventing or remediating pathogenic biofilm colonization. Listeria monocytogenes is well known for its ability to form biofilm and to establish harborages on food-processing equipment, making its eradication even more difficult, which may led to food products contamination. Many lactic acid bacteria (LAB) are known for their ability to inhibit growth of spoilage and pathogenic microorganisms by producing antimicrobial compounds. In addition, some studies have reported the capacity of Lactobacillus strains to grow on different surfaces as biofilm without losing their ability to produce inhibitory metabolites such as bacteriocins. Consequently, the ability to inhibit pathogen biofilm formation by bacteriocinogenic and biofilm producer lactobacilli during 10 days at low temperature was investigated. Petri dish containing MRS broth and chips (1 cm2) of stainless steel (SS) and polytetrafluoroethylene (PTFE) were inoculated with each biofilm and anti-Listeria compounds producer Lactobacillus strains, incubated at 10 °C during 4, 6 and 10 day sand evaluated by scanning electron microscopy (SEM). The micrographs showed that all three strains were able to colonize PTFE surfaces as biofilm while no lactobacilli cells were found on SS chips at 4 days. Three-dimensional structures appeared aggregates that evolved to dense bacterial mats in which spaces or channels could be distinguished with high magnification. At 6 days, a slower colonization of Lactobacillus sakei CRL1862 on both surfaces was observed while L. curvatus CRL705 and CRL1532 showed similar dense bacterial mass. At 10 days, L. curvatus CRL1532 population remained stable whereas few and any cells of L. sakei CRL1862 and L. curvatus CRL705, respectively were observed on PTFE surface. Interestingly, some microscopic views revealed the presence of fibrils around Lactobacillus cells attached to PTFE chips, this probably being polymeric material such as exopolysaccharide. Few and single cells of lactobacilli were attached to the SS chips, and no obvious attachment matrix was apparent at 6 and 10 days. In line with these findings, the three evaluated Lactobacillus strains have the potential to form biofilms more efficiently in PTFE than SS surface.