Bacterial diversity on stainless steel surfaces of egg processing companies and potential of selected isolates to spoil liquid whole egg products

AIMS: To assess the bacterial diversity in the French egg processing industry and to explore the adhesion and spoilage potential of selected bacteria. METHODS AND RESULTS: Sterile stainless steel chips were suspended for 2 months inside the pipelines of seven egg processing companies, before and after the pasteurizer, at warm and cold seasons. After exposure, the bacterial diversity was assessed by 16S rDNA sequencing. The 231 collected isolates were mainly facultative anaerobic Gram positive bacteria, such as Streptococcus, Staphylococcus, Bacillus and Kocuria. Sixty-five representative isolates were further characterized in vitro regarding the potential for adhesion and egg product spoilage. A high diversity was observed from one genus to another. Kocuria and Rothia isolates showed significantly higher adhesion than the isolates of the other genera. Only the isolates belonging to the genera Bacillus and Lysinibacillus, associated with high enzymatic activities on a solid egg-based medium, were able to induce spoilage of liquid whole egg. CONCLUSIONS: Bacteria collected on stainless steel surfaces placed in egg processing industries could be associated to liquid egg product spoilage. SIGNIFICANCE AND IMPACT OF THE STUDY: This study provides new insights on the bacterial contamination in egg processing companies and represents a first step for the effective control of undesirable bacteria in liquid egg products.