Formation of biofilms on microplastics in the food chain and their role as vectors of transfer of foodborne pathogens (literature review, part 2)

The first part of the review, “Microbial risks associated with microplastics in the food chain and possible control measures”, examined the pathways by which microplastics enter the human digestive tract and mechanisms of their adverse effects mediated by interactions with the microbiota and the intestinal mucosal barrier. This part of the review is devoted to the mechanism of microbial biofilm forming directly contacting wth the the mucin layer of the mucosa, formed on micro- and nanoplastics, and their role as vectors of transfer of pathogenic microorganisms, their toxins, and genes of transmissible antimicrobial resistance. It is shown that the surfaces of micro- and nanoplastic particles in various objects of the food chain can serve as an adhesive framework for bacteria, microalgae, viruses, a number of micromycetes, as well as low molecular weight microbial metabolites and other biomolecules. It is noted that in associations of micro- and nanoplastics with bacteria, protozoa, and microalgae, among which there may be pathogens of food toxic infections and invasions, the functional properties of the latter change, virulence often increases, as well as elevates antimicrobial resistance due to the fixing effect of biofilm and better survival of microorganisms in the presence of nutrient substrate in the so-called “protein crown” (inner layer of biofilm). It is emphasized that bacteria possessing mucolytic and proteolytic enzymes, in particular, representatives of the genus Vibrio and Pseudomonadaceae, are particularly active in biofilms, which aggravates the share of these pathogens in the structure of modern acute intestinal infections and food poisoning. Examples are given that ingestion of such complexes in the human gastrointestinal tract can cause an abnormally acute response of the mucosal immune system, which in turn can be a trigger factor of the polyclonal response underlying atopy. The data on the possibility of microplastic biofilms contaminating fish and seafood, primarily obtained in aqua- and mariculture, toxins of cyanobacteria dangerous for humans in low doses are presented. Taking into account the described nature of microbiological risks associated with contamination of foodstuffs and other objects of the food chain with micro- and nanoplastic particles associated with microbial biofilms and the reality of direct and indirect harm to human health caused by them, the review formulates the necessity of substantiation of preventive countermeasures and consumer protection, and gives specific examples of their implementation in the food industry.