Residential Bacteria on Surfaces in the Food Industry and Their Implications for Food Safety and Quality

Abstract

Surface hygiene is commonly measured as a part of the quality system of food processing plants, but as the bacteria present are commonly not identified, their roles for food quality and safety are not known. Here, we review the identity of residential bacteria and characteristics relevant for survival and growth in the food industry along with potential implications for food safety and quality. Sampling after cleaning and disinfection increases the likelihood of targeting residential bacteria. The increasing use of sequencing technologies to identify bacteria has improved knowledge about the bacteria present in food premises. Overall, nonpathogenic Gram-negative bacteria, especially Pseudomonas spp., followed by Enterobacteriaceae and Acinetobacter spp. dominate on food processing surfaces. Pseudomonas spp. persistence is likely due to growth at low temperatures, biofilm formation, tolerance to biocides, and low growth requirements. Gram-positive bacteria are most frequently found in dairies and in dry production environments. The residential bacteria may end up in the final products through cross-contamination and may affect food quality. Such effects can be negative and lead to spoilage, but the bacteria may also contribute positively, as through spontaneous fermentation. Pathogenic bacteria present in food processing environments may interact with residential bacteria, resulting in both inhibitory and stimulatory effects on pathogens in multispecies biofilms. The residential bacterial population, or bacteriota, does not seem to be an important source for the transfer of antibiotic resistance genes to humans, but more knowledge is needed to verify this. If residential bacteria occur in high numbers, they may influence processes such as membrane filtration and corrosion.

Microbial Ecology Evaluation of an Iberian Pig Processing Plant through Implementing SCH Sensors and the Influence of the Resident Microbiota on Listeria monocytogenes

“…There is a wide variety of bacterial families and variability in terms of the obtained results since many factors are at play such as the nature of the worked product. Nevertheless, Pseudomonas spp., Enterobacteriaceae, Acinetobacter spp., Bacillus spp., Staphylococcus spp., and lactic acid bacteria generally dominate on the surfaces of food facilities [8]. Persistent microorganisms can reach the final products through cross-contamination and consequently spoil them.…”

Evaluation of ATP bioluminescence‐based methods for hygienic assessment in fish industry

“…The RLU per million CFU was more than 1000 times lower for L. monocytogenes than for Acinetobacter sp. The ATP signal of L. monocytogenes is low, L. monocytogenes is also usually present in lower numbers than other bacteria in the industry (Møretrø and Langsrud ). Taken together, this shows that it is difficult to use ATP as a direct measure of bacterial levels after cleaning and disinfection, especially for subgroups such as L. monocytogenes representing a minority of the total number of bacteria.…”

“…In addition, nine other bacterial strains were included, all isolated from Norwegian salmon processing plants, and representing the genera Acinetobacter (two strains), Aeromonas (2), Pseudomonas (2), Serratia (2) and Shewanella (1). These genera are frequently found in Norwegian salmon processing plants (Langsrud et al ; Møretrø et al ) and in fish processing environments in general (Møretrø and Langsrud ). All bacteria were stored at −80°C.…”

“…During processing, fish residues may accumulate in the processing environment and result in growth of micro‐organisms. Such micro‐organisms can again be transferred to fish products through cross‐contamination and impact food safety and food quality (Møretrø and Langsrud ). As it may be difficult to eradicate bacteria established in the processing environment, for example as biofilms, the emphasis should be on to preventing establishing of bacteria.…”

“…Many processing plants use a considerable amount of resources on monitoring the cleanliness of the processing environment by sampling and analysing for total bacteria by conventional cultivation‐dependent methods (Møretrø and Langsrud ). Plants producing ready‐to‐eat products such as cold‐smoked salmon or sushi may also analyse for the pathogenic bacteria Listeria monocytogenes .…”