Antimicrobial compounds produced by Bacillus spp. and applications in food.

The Bacillus genus is a heterogeneous group of Gram-positive, facultative anaerobic, endospore-forming bacteria spread into the environment, even though soil is generally accepted as its natural reservoir. The ability to produce endospores allows Bacillus to withstand extreme environmental conditions as those occurring in food processing. Bacillus spp., particularly B. subtilis, are usually found in foods such as dry cured sausages, cheeses, traditional fermented milks, sourdough, etc. in which they cooperate with other microorganisms during fermentation, releasing amylases, lipases and proteases. One of the main characteristics shared among Bacillus strains is the ability to produce a wide range of antimicrobial compounds active against bacteria and fungi. Even though microbial control exerted by these metabolites was demonstrated in plant environments, few reports focused their attention on how these compounds can interact with food microbiota. One single Bacillus strain is often able to produce several types of molecules stable over a wide range of pH and temperature and partially resistant to enzyme treatments. These substances are usually protein- and peptide-based compounds such as enzymes, bacteriocins and lipopeptides. Thanks to their chemical characteristics and inhibitory spectrum, Bacillus producer strains could be applied during food processing as innovative tools for the control of food pathogens and spoilage microorganisms. In this paper, current and potential applications of Bacillus strains in food environments are discussed, focussing on antimicrobial compounds contributing to improve food safety and quality.