A Review of Horizontal Gene Transfer for the Natural Functional Improvement of Microorganisms Relevant to Food Technology

Different groups of microorganisms—namely lactic acid bacteria (LAB), coagulase-negative staphylococci (CNS), dairy propionibacteria, yeasts, and molds—play essential roles in producing safe fermented foods of animal and plant origin with high nutritional value and sensory quality. The acquisition of genetic traits with technological relevance by natural horizontal gene transfer (HGT) via transformation, conjugation, phage transduction, and other routes would broaden the spectrum of beneficial activities exerted by individual microbial strains with no limitations for their use in food. Therefore, this critical review aimed to identify the potential for natural genetic improvement of microbial species relevant to food technology, based on reports of natural genetic exchanges occurring in environmental niches and laboratory conditions. Results showed that the species most frequently involved in natural HGT is Lactiplantibacillus plantarum, followed by Streptococcus thermophilus and Lactococcus lactis. Extensive HGT events enabling adaptation to food have been observed in domesticated filamentous fungi. The transferred traits of technological relevance include resistance to various stress factors, exopolysaccharide (EPS) and bacteriocin production, protein and amino acid utilization, phage immunity, lactose and citrate metabolism in dairy species, and use of plant carbohydrates in vegetable adapted species. Methods suitable for detecting HGT events in microbial communities have been developed and can aid in isolating improved strains for use in fermented foods.