Resumo

SIERRA-GARCIA, Isabel N.; ROMERO-TABAREZ, Magally  e  ORDUZ-PERALTA, Sergio. DETERMINATION OF THE ANTIMICROBIAL AND INSECTICIDAL ACTIVITIES IN EXTRACTS PRODUCED BY BACTERIA ISOLATED FROM SOIL. Actu Biol [online]. 2012, vol.34, n.96, pp.5-19. ISSN 0304-3584.

Colombia is considered one of the countries with the greatest biological diversity, but very little of this diversity has been explored to identify biologically active substances. Secondary bacterial metabolites may exhibit activity to plant and animal pathogens and represent alternative biotechnologies for industry. The objective of this study was to evaluate the potential of different bacterial strains isolated from soils in order to produce biologically active substances like antibacterial, antifungal, and insecticidal substances. A total of 92 methanolic extracts of secondary bacterial metabolites were evaluated. The antibacterial and antifungal activity was evaluated by means of disk diffusion tests against diverse bacteria such as Bacillus subtilis, Enterococcus faecalis, Escherichia coli and Staphylococcus aureus and against different fungi such as Alternaria sp., Colletotrichum sp., Fusarium sp., Pestalotia sp. and Verticillium sp. Insecticide activity was evaluated by determining the effect of the extracts on larval mortality of Aedes aegypti (Diptera) and Spodoptera frugiperda (Lepidoptera). 50% of the bacterial isolates exhibited some form of activity, with the greatest biological activity detected in the extracts produced by bacteria from the genus Bacillus, identified by means of analysis of ribosomal 16S DNA and by biochemical characterization with API® 50 CHB, MicroLog^TM and Biolog. The Bacillus species identified have been characterized as producers of broad spectrum antimicrobial compounds or various compounds with differing activities. The biological activity exhibited by the extracts show that terrestrial microorganisms and especially Bacillus species are prolific producers of diverse bioactive substances.

Palavras-chave : active compounds; antimicrobials; bacterial extracts; insecticide activity; Bacillus.

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