Identification of bacterial communities of fermented cereal beverage Boza by metagenomic analysis

Bacterial microbiota of directly studied and pre-enriched Boza samples were investigated by metagenomic analysis. Virulence gene contents, biofilm formation, antibiotic susceptibility and clonal relationships of enterococci present in pre-enriched Boza samples were determined. Chemical properties of the samples were also investigated. Although directly studied samples showed a dominance by Lactococcus, Lactobacillus, Leuconostoc, and Streptococcus. NGS upon pre-enrichment of the same Boza samples demonstrated a dominance by Lactococcus, Enterococcus, Escherichia/Shigella, Bacillus, and Lactobacillus. All enterococci were identified as Enterococcus faecium and none of them was positive for vanA, vanB, vanC1, vanD, vanE, vanG, agg, gelE, efaAfs, cylA, ace, hyl, cob, cylB, and cylM genes. However, efaAfm, ccf, cpd, and esp genes were detected in the strains. Only one strain formed biofilm and seven strains showed low adherence. E. faecium strains were resistant to rifampin and erythromycin. PFGE revealed 54–100% clonal relationships of E. faecium strains. Percent acidity of Boza samples were 0.14%–0.51%, pH was 3.00–4.07, protein content was 0.35–1.23 mg/100 mg, total sugar content was 9.64–19.21 mg/100 mg Boza, crude ash content was 0.05–0.18 mg/100 mg dry sample, total dry matter was 13.79–28.04 mg/100 mg. Our results indicate to importance of the dynamics nature of microbial communities involved in Boza fermentation and virulence properties of enterococci.