SEOUL, South Korea — Foodborne illnesses are typically caused by microorganisms living in organized and complex networks called "biofilms." These can be "mono-species" or "multi-species" biofilms. Eating food contaminated with pathogenic microbes causes an estimated 420,000 deaths annually according to the World Health Organization (WHO). While some microbes such as lactic acid bacteria confer benefits in food safety and nutrition, no current physical or chemical methods can eliminate unfriendly biofilms from food entirely without causing adverse side effects.
Now, in a new article published in Trends in Food Science & Technology, one of the top journals in the food science field, Professor Sang-Do Ha from Chung-Ang University, South Korea, along with his colleagues, has reviewed the existing literature on biofilm formation and its impact on food industries to identify effective eco-friendly approaches to eradicate unfriendly microbes.
"Contamination due to biofilms can occur in all types of food — raw, minimally processed, fresh and ready-to-eat," said Ha. "Pathogenic biofilms can accumulate on various food processing machines like milk storage tanks and the conveyer belts of meat-processing plants or on the surface of packaging equipment."
Based on previous studies, the researchers propose that both mono- and multi-species bacterial biofilms can be countered by biological agents derived from microorganisms, such as bacteriocins, a heterogenous group of proteins produced by microorganisms such as lactic acid bacteria and noted for their green and safe properties to thwart the transmission of pathogenic microorganisms, inhibiting biofilm formation; microbial-derived "surfactants," naturally produced by microorganisms and are both hydrophobic (repelled by water) and hydrophilic (attracted to water) and weaken the bacteria-to-bacteria and bacteria-to-surface connections; "bacteriophages," which are currently used in food plants and are naturally occurring viruses that specifically target foodborne bacteria to control biofilm formation in both mono- and mixed-bacterial species; biological catalysts/enzymes such as lyases and hydrolases that disrupt cell-to-cell communication systems and break down biofilm structures; and "quorum-quenching compounds" that inhibit specific gene expression in bacteria to disrupt cell-to-cell communications and thus prevent biofilm formation.
The use of chitosan (a sugar which disrupts the bacterial cell membrane), bacteriocin-like inhibitory substances (active anti-biofilm agents that work much like bacteriocins) and bacterial second message inhibitors (which could steer the transmission of signals within the cell to avoid forming biofilms), was also mentioned by the researchers as additional strategies.
Ha believes that the right combination of two or more approaches will be necessary to disrupt the diverse matrix of components in bacterial biofilms.
"These emerging novel approaches need to be verified by extensive in vitro and in vivo studies," he said. "We need to see more multidisciplinary research so that improvements to existing processes can be developed alongside the creation of novel biological agents that are easier and cheaper to produce."