Bacteria strains with the potential to synthesize substances with enhanced antimicrobial activity
Year: 2025
Type: conference-paper
Abstract: It is known that bacteria, in particular Bacillus spp. are capable of producing in the medium various secondary metabolites, diverse in function and structure, such as peptide antibiotics like gramicidins, bacitracins and tyrocidins that possess pronounced antimicrobial activity. Therefore, the search for pathways to stimulate the synthesis of exometabolites produced by bacterial strains with pronounced antimicrobial activity becomes significant and attracts much more attention. The given study aimed to fortify the ability of microorganisms to synthesize bioactive substances with antimicrobial effect with the use of iron oxide nanoparticles (NPs) as stimulators. Three strains of Bacillus spp. bacteria deposited in the National Collection of Nonpathogenic Microorganisms as objects of biotechnological interest were used in this research: B. subtilis CNMN-BB-10, B. velezensis CNMN-BB-12 and B. velezensis CNMN-BB-16. Cultivation was carried out on NB medium at +30 ºC for 48 hours by continuous shaking at 180 rpm. Fe3O4 NPs (IONPs) were used as stimulators, added in the medium at concentrations of 5, 10 and 15 mg/L. After 48 hours of incubation, the biomass was separated from the culture liquid by centrifugation to obtain cell free supernatant (CFS), then antimicrobial activity was determined by well plate method, on bacteria strains Agrobacterium tumefaciens CNMN-AB-01, Corynebacterium michiganense CNMN-CrB-01, Erwinia carotovora CNMN-BE01 and Xanthomonas campestris CNMN-BX-01; and fungi Fusarium oxysporum, F. solani, F. graminearum, Aspergillus fumigatus and A. flavus. For well method, a quantity of 100 μL CFS was poured into wells of 8 mm diameter in Petri plates with medium already containing inoculated bacterial or fungal strains. After, 48 hours of bacteria incubation and 3-5 days of fungi incubation, the diameter of the growth inhibition zones was measured. The results obtained after cultivation of B. subtilis CNMN-BB-10, B. velezensis CNMN-BB-12 and B. velezensis CNMN-BB-16 in the presence of IONPs, demonstrate increased antimicrobial activity at all studied concentrations. Of the bacterial strains the most sensitive was A. tumefaciens CNMN-AB-01, where the zones of inhibition of its growth and development exceeded the control sample by 25-36 %, and the growth and development of E. carotovora CNMN-BE-01 and X. campestris CNMN-BX-01, was inhibited by more than 17-22 %, in comparison with control. In contrast, growth and development of fungal strains of Fusarium spp. was totally inhibited in the presence of IONPs, in comparison with area of about 20 mm produced by the control. Growing the bacteria on media supplemented with 5 and 10 mg/L IONPs, also leads to the growth of Aspergillus fumigatus and A. flavus strains being stopped, and with their increase the inhibition is manifested in areas between 21-30 mm, depending on the strain. Thus, it was established that iron oxide NPs, supplemented in the culture medium of some bacterial strains, stimulate the biosynthesis processes of bioactive substances in the medium with enhanced antibacterial and antifungal activity, and as a result the obtained products can be used with biotechnological and medical applications.
Language: English
Subfield: Applied Microbiology and Biotechnology
Field: Immunology and Microbiology
Domain: Life Sciences
Open Access status: bronze
OpenAlex ID: W7204694182