Comprehensive analysis of the effect of essential elements on bacterial strains of Bacillus sp. in an model experiment in vitro

Relevance . Modern literature presents numerous experimental data on the use of the bioremediation potential of bacterial strains to correct mono and polymetal pollution of ecosystems at various levels of organization. In our work, a systematic analysis was carried out to assess the degree of influence of excess concentrations of zinc, iron and copper on dynamic growth indicators, the level of tolerance, sorption capacity and antagonistic characteristics of Bacillus sp. strains. in model experiments in vitro . Methods . The research was conducted at the department of Biochemistry and Microbiology of Orenburg State University in 2023. As objects of research, they used museum samples of probiotic strains of Bacillus sp. : B. subtilis 534 (Sporobacterin, Bakoren LLC, Orenburg, Russia), B. cereus IP 5832 (Flonivin BS, Galenika Crna Gora, D.O.O., Montenegro), B. licheniformis VKPM B 7038 («Vetom 4» NPF Research Center LLC, Novosibirsk region, Russia), as well as clinical isolates of E. coli and S. aureus . Metal salts FeSO 4 × 7H 2 O, CuSO 4 × 5H 2 O and ZnSO 4 × 7H 2 O (JSC Lenreactive St. Petersburg, Russia) were used as growth-regulating factors of mono- and polymetal contamination of the substrate. Results . The data obtained indicate high levels of sorption of iron up to 47.98% and zinc up to 44.96% by the studied strains. The negative effect of a massive cationic load of zinc and copper on the antagonistic activity of the studied strains against both gram-positive ( S. aureus ) and gram-negative ( E. coli ) model microorganisms was experimentally established. Iron has a stimulating effect on the antagonistic characteristics of B. cereus IP 5832 and B. licheniformis VKPM B 7038 against E. coli by 32.63% ( p < 0.01) and 36.77% ( p < 0.05).