Bacillus species produce different classes of antimicrobial and antioxidant substances: peptides or proteins with different structural compositions and molecular masses and a broad range of volatile organic compounds (VOCs), some of which may serve as biomarkers for microorganism identification. The aim of this study is the identification of biologically active compounds synthesized by five Bacillus species using gas chromatography coupled to mass spectrometry (GC–MS). The current study profoundly enhances the knowledge of antibacterial and antioxidant metabolites ensuring the unambiguous identification of VOCs produced by some Bacillus species, which were isolated from vegetable samples of potato, carrot, and tomato. Phylogenetic and biochemical studies were used to identify the bacterial isolates after culturing. Phylogenetic analysis proved that five bacterial isolates BSS12, BSS13, BSS16, BSS21, and BSS25 showed 99% nucleotide sequence similarities with Bacillus safensis AS-08, Bacillus cereus WAB2133, Bacillus acidiproducens NiuFun, Bacillus toyonesis FORT 102, and Bacillus thuringiensis F3, respectively. The crude extract was prepared from bacterial isolates to assess the antibiotic resistance potency and the antimicrobial potential against various targeted multidrug-resistant strains, including yeast strains such as Candida albicans, Candida krusei, and bacterial strains of Enterococcus hirae, Escherichia coli, Klebsiella aerogenes, Klebsiella pneumoniae, Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus group B, Streptococcus mutans, Shigella sonnei, Salmonella enteritidis, Serratia marcescens, Pseudomonas aeruginosa, and Proteus vulgaris. GC–MS analysis of bacterial strains found that VOCs from Bacillus species come in a variety of chemical forms, such as ketones, alcohols, terpenoids, alkenes, etc. Overall, 69 volatile organic compounds were identified from five Bacillus species, and all five were found to share different chemical classes of volatile organic components, which have a variety of pharmacological applications. However, eight antibacterial compounds with different concentrations were commonly found in all five species: acetoin, acetic acid, butanoic acid, 2-methyl-, oxime-, methoxy-phenyl, phenol, 1,2-benzenedicarboxylic acid, bis(2-methylpropyl) ester, nonanoic acid, and hexadecanoic acid, methyl. The present study has demonstrated that bacterial isolates BSS25, BSS21, and BSS16 display potent inhibitory effects against Candida albicans, while BSS25, BSS21, and BSS13 exhibit the ability to restrain the growth and activity of Candida krusei. Notably, BSS25 and BSS21 are the only isolates that demonstrate substantial inhibitory activity against Klebsiella aerogenes. This disparity in inhibitory effects could be attributed to the higher concentrations of acetoin in BSS25 and BSS21, whereas BSS16 and BSS13 have relatively elevated levels of butanoic acid, 2-methyl-. Certainly, the presence of acetoin and butanoic acid, 2-methyl-, contributes to the enhanced antibacterial potential of these bacterial strains, in conjunction with other organic volatile compounds and peptides, among other factors. The biology and physiology of Bacillus can be better understood using these results, which can also be used to create novel biotechnological procedures and applications. Moreover, because of its exceptional ability to synthesize and produce a variety of different antibacterial compounds, Bacillus species can serve as natural and universal carriers for antibiotic compounds in the form of probiotic cultures and strains to fight different pathogens, including mycobacteria.

Numerous natural habitats, such as soil, air, fermented foods, and human stomachs, are home to different Bacillus strains. Some Bacillus strains have a distinctive predominance and are widely recognized among other microbial communities, as a result of their varied habitation and physiologically active metabolites. The present study collected vegetable products (potato, carrot, and tomato) from local markets in Almaty, Kazakhstan. The bacterial isolates were identified using biochemical and phylogenetic analyses after culturing. Our phylogenetic analysis revealed three Gram-positive bacterial isolates BSS11, BSS17, and BSS19 showing 99% nucleotide sequence similarities with Bacillus subtilis O-3, Bacillus subtilis Md1-42, and Bacillus subtilis Khozestan2. The crude extract was prepared from bacterial isolates to assess the antibiotic resistance potency and the antimicrobial potential against various targeted multidrug-resistant strains, including Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus group B, Streptococcus mutans, Candida albicans, Candida krusei, Pseudomonas aeruginosa, Shigella sonnei, Klebsiella pneumoniae, Salmonella enteritidis, Klebsiella aerogenes, Enterococcus hirae, Escherichia coli, Serratia marcescens, and Proteus vulgaris. This study found that the species that were identified have the ability to produce antibiotic chemicals. Additionally, the GC–MS analysis of three bacterial extracts revealed the presence of many antibiotic substances including phenol, benzoic acid, 1,2-benzenedicarboxylic acid and bis(2-methylpropyl), methoxyphenyl-oxime, and benzaldehyde. This work sheds light on the potential of Bacillus to be employed as an antimicrobial agent to target different multidrug-resistant bacterial strains. The results indicate that market vegetables may be a useful source of strains displaying a range of advantageous characteristics that can be used in the creation of biological antibiotics.

The burden of pneumococcal disease remains a global challenge. The purpose of this work was to assess the serotype composition of S. pneumoniae circulating among children under 5 years of age in Eastern European (the Russian Federation and the Republic of Belarus) and Central Asian (the Republic of Kazakhstan) countries which are characterized by close cultural and economic ties. The most pronounced changes were noted in the Russian Federation. In the pre-vaccination period (before 2015) PCV13 covered 66 % - 90 % of prevalent serotypes. In 2016-2018 coverage decreased to 59.2 %. During this study period (2020-2023) PCV 13 related serotypes in healthy children and those with respiratory infections dropped further to 23.2 % and 35.7 %, respectively. In Kazakhstan, vaccine-related serotypes among healthy children and children with RTI were more prevalent than in Russia (51.5-58.6 % vs 23.2-35.7 %) despite both countries having introduced pneumococcal vaccination at the same time, and both countries reporting vaccination rates above 90 % in children under 5 years of age. In the Republic of Belarus, in the absence of a universal vaccination program, PCV13 covers 86.4 % of serotypes. Serotypes 19F (31 %), 3 (16.2 %), 19 A (10.3 %), and 14 (10 %) predominate among S. pneumoniae causing acute otitis media in children. Expanding the serotype/serogroup composition of new vaccines may provide protection against potentially invasive non-vaccine strains in the future.

Bacillus species produce different classes of antimicrobial and antioxidant substances: peptides or proteins with different structural composition and molecular mass and a broad range of volatile organic compounds (VOCs), some of which may serve as biomarkers for microorganism identification. The aim of this study is the identification of biologically active compounds synthesized by five Bacillus species using gas chromatography coupled to mass spectrometry (GC–MS). The current study profoundly enhances the knowledge of antibacterial and antioxidant metabolites ensuring the unambiguous identification of VOCs produced by some Bacillus species, which were isolated from vegetable samples of potato, carrot, and tomato. Phylogenetic and biochemical studies were used to identify the bacterial isolates after culturing. Phylogenetic analysis proved that five bacterial isolates BSS12, BSS13, BSS16, BSS21, and BSS25 showed 99% nucleotide sequence similarities with Bacillus safensis AS-08, Bacillus cereus WAB2133, and Bacillus acidiproducens NiuFun, Bacillus toyonesis FORT 102 and Bacillus thuringiensis F3, respectively. The crude extract was prepared from bacterial isolates to assess the antibiotic resistance potency and the antimicrobial potential against various targeted multidrug-resistant strains, including Candida albicans, Candida krusei, Enterococcus hirae, Escherichia coli, Klebsiella aerogenes, Klebsiella pneumoniae, Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus group B, Streptococcus mutans, Shigella sonnei, Salmonella enteritidis, Serratia marcescens, Pseudomonas aeruginosa, and Proteus vulgaris. GC–MS analysis of bacterial strains found that VOCs from Bacillus species come in a variety of chemical forms, such as ketones, alcohols, terpenoids, alkenes, etc. Overall, 69 volatile organic compounds were identified from five Bacillus species, and all five were found to share different chemical classes of volatile organic components, which have a variety of pharmacological applications. However, 8 antibacterial compounds with different concentrations were commonly found in all five species: acetoin, acetic acid, butanoic acid, 2-methyl-, oxime-, methoxy-phenyl, phenol, 1,2-benzenedicarboxylic acid, bis(2-methylpropyl) ester, nonanoic acid, and hexadecanoic acid, methyl. The biology and physiology of Bacillus can be better understood using these results, which can also be used to create novel biotechnological procedures and applications. Moreover, because of its exceptional ability to synthesize and produce a variety of different antibacterial compounds, Bacillus species can serve as natural and universal carriers for antibiotic compounds in the form of probiotic cultures and strains to fight different pathogens, including mycobacteria.

Background: Candida spp. are opportunistic fungi whose pathogenic potential arises from interactions among multiple phenotypic traits that may not be captured by conventional single-factor analyses. This study aimed to identify multidimensional phenotypic virulence profiles among clinical Candida isolates using unsupervised machine learning. Methods: A total of 107 nasopharyngeal isolates recovered from COVID-19 convalescent patients in Almaty, Kazakhstan, during 2021–2022 were evaluated for biofilm formation, phospholipase, proteinase, hemolytic activities and susceptibility to fluconazole, voriconazole, itraconazole, and amphotericin B. Phenotypic data were analyzed using principal component analysis, Uniform Manifold Approximation and Projection, hierarchical clustering, permutational multivariate analysis of variance (PERMANOVA), Random Forest, and SHAP analysis. Results: Candida albicans predominated among the isolates (69.2%), and non-albicans Candida species accounted for 30.8%. Interspecies differences were observed in biofilm formation (p = 0.048) and itraconazole minimum inhibitory concentrations (p < 0.001). Three phenotypic clusters independent of species were identified (PERMANOVA: pseudo-F = 6.72, p = 0.0002). Across 20 repeated 5-fold cross-validation runs, the Random Forest model achieved an aggregated accuracy of 0.785, a mean balanced accuracy of 0.518 (95% CI: 0.461–0.577), and a macro-F1 score of 0.504 (95% CI: 0.444–0.559). SHAP identified itraconazole susceptibility, biofilm formation, and phospholipase activity as the strongest predictors. Conclusions: These findings demonstrate that integrating microbiological phenotyping with machine learning can reveal multidimensional virulence profiles beyond conventional species-based classification.