Residential Bacteria in the Food Industry: Why? Who? So What?

Bacteria are frequently present on surfaces in food processing environments. The majority of these bacteria are non-pathogenic. Pathogenic bacteria are, usually, present sporadically and in low numbers. Most food processors do not know the identity of the non-pathogenic, residential bacteria found in their production plant. Increased knowledge is important to understanding how the bacteria in the food production environment can affect food quality and food safety. The introduction of sequence based microbiota analyses has given new insight into the identity of microorganisms on surfaces in the food industry. Gram negative bacteria dominate in most processing environments, with Pseudomonas as the dominating genus followed by Acinetobacter and Enterobacteriaceae. In some environments, especially dairies, Gram positive bacteria are more frequently isolated. Characteristics such as growth at low temperatures, low growth requirements, biofilm formation, tolerance to drying, heat, and sanitizers are believed to be important for the growth and survival of residential bacteria in food processing environments. If the bacteria on machines and equipment are transferred to food during processing and are able to grow in that food, they may have a role in spoilage. Several types of important spoilage bacteria are common in food processing environments, such as Pseudomonas, Enterobacteriaceae and lactic acid bacteria. Also, it has been described that bacteria dominating the food industry can influence the fate of pathogens in the processing environment and, thus, affect food safety.