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Representatives of the genus Bacillus are multifunctional microorganisms with a broad range of applications in both traditional fermentation and modern biotechnological processes. Bacillus spp. has several beneficial properties. They serve as starter cultures for various traditional fermented foods and are important biotechnological producers of enzymes, antibiotics, and bioactive peptides. They are also used as probiotics for humans, in veterinary medicine, and as feed additives for animals of agricultural importance. The beneficial effects of bacilli are well-reported and broadly acknowledged. However, with a better understanding of their positive role, many questions have been raised regarding their safety and the relevance of spore formation in the practical application of this group of microorganisms. What is the role of Bacillus spp. in the human microbial consortium? When and why did they start colonizing the gastrointestinal tract (GIT) of humans and other animals? Can spore-forming probiotics be considered as truly beneficial organisms, or should they still be approached with caution and regarded as "benefits with concerns"? In this review, we not only hope to answer the above questions but to expand the scope of the conversation surrounding bacilli probiotics. [ABSTRACT FROM AUTHOR]

Aims: The objective of this study was to isolate multifunctional bacteriocin‐producing strains; to characterize the expressed bacteriocin for the control of Listeria monocytogenes and vancomycin‐resistant Enterococcus; to evaluate the safety of studied strains; and to explore their antifungal activity. Methods and Results: Two Pediococcus strains were isolated from silage samples obtained from an organic farm in Belogradchik, Bulgaria. The strains were identified by 16S rRNA sequencing analysis and characterized as bacteriocins producers. Strong antimicrobial activity was detected against more than 74 different strains of Listeria monocytogenes, 27 different vancomycin‐resistant Enterococcus strains. In addition, studied strains were able to inhibit the growth of strains of Alternaria alternate, Aspergillus flavus, Aspergillus niger, Cladosporium sphaerospermum, Penicillium chrysogenum and Penicillium expansum. Some aspects of the antimicrobial mode of action were evaluated, including killing curves and aggregation properties. Both strains generated positive PCR results for the presence of pediocin PA‐1, but not for other bacteriocins evaluated in this screening process. Metabolomic analysis of the cell‐free supernatants from both strains was performed in order to explain the observed antifungal activity against different moulds. According to PCA and PLS‐DA score plot, P. acidilactici ST3522BG and P. pentosaceus ST3633BG were clearly clustered from control (MRS). Increases in the production of benzoic acid, 2‐hydroxyisocaproic acid, β‐phenyl‐lactic acid, α‐hydroxybutyric acid and 1,3‐butanediol were recorded, these metabolites were previously described as antifungal. Conclusions: Pediococcus acidilactici ST3522BG and P. pentosaceus ST3633BG were evaluated as producing bacteriocin strains with high specificity against Listeria and vancomycin‐resistant Enterococcus species. In addition, both investigated Pediococcus strains were evaluated as producer of effective antifungal metabolites with potential for the inhibition of mycotoxin‐producing moulds. Significance and Impact of the Study: To the best of our knowledge, this report is a pioneer in the evaluation of Pediococcus strains isolated from silage with highly specific bacteriocinogenic antimicrobial activity against Listeria spp. and vancomycin‐resistant Enterococcus spp., and antifungal activity against mycotoxin‐producing moulds. [ABSTRACT FROM AUTHOR]