ANTIMICROBIAL ACTIVITY OF ANTARCTIC STREPTOMYCETES AGAINST PEPPER BACTERIAL SPOT CAUSING AGENTS MARTA
ENCHEVA-MALINOVA1*, TACA VANCHEVA1, NIKOLAY BADZHINEROV1, VERONIKA KOLEVA1, SAVA TISHKOV1, NEVENA BOGATZEVSKA2, PENKA MONCHEVA1
1 – Department of General and Industrial Microbiology, Faculty of Biology, Sofia University “St. Kliment Ohridski”, Sofia, Bulgaria
2 – Institute of Soil Science, Agrotechnologies and Plant Protection “N. Pushkarov”, Sofia, Bulgaria
*Corresponding author: martaen4eva@gbg.bg
Keywords: Streptomycetes, antibacterial activity, bacterial spot of pepper, phytopatho-genic bacteria, Xanthomonas
Abstract: Streptomycetes are microorganisms that synthesize various biologically active substances, most of which with antimicrobial activity. In this study three Streptomyces strains isolated from Antarctic soils were screened for in vitro and in vivo antibacterial activity towards causative agents of bacterial spot of pepper – Xanthomonas vesicatoria, Xanthomonas euvesicatoria and Xanthomonas gardneri. Cell-free filtrates of cultural media and mycelium extracts obtained in 120 h of the cultivation of the streptomycetes were used. The in vitro antimicrobial activity was determined by the agar diffusion method. All streptomycetes showed antibacterial effect which varied for different test-bacteria and the producer strains. The extracts from the mycelia of the strains were more active. The potential of the streptomycetes for in vivo control of phytopathogenes was investigated by treatment of pepper seeds infected with X. vesicatoria, X. euvesicatoria and X. gardneri using streptomycetes cell-free filtrates and mycelium extracts. The cell-free extracts did not show activity, whereas the extracts manifested high decontamination activity (between 94 and 100%) decreasing slightly seed germination (between 8 and 30%).