Abstract

The obtention of secondary metabolites from bacterial filtrates has permitted the identification of new compounds with diverse biotechnological applications. These metabolites were generated under different conditions. Eighty-six strains of Pseudomonas were isolated from mineral soils of the central region of Zacatecas to determine if these generated secondary metabolites possess antimicrobial activity against phytopathogenic microorganisms. Afterwards, parameters, such as nutrients, were identified using seven different mediums, time of production of bioactive metabolites using growth curves, the determination of antimicrobial activity during fermentation, and their minimum inhibitory concentration (MIC). One strain of Pseudomonas was able to generate specific secondary metabolites for one or all microorganisms during different stages of the growth curve. The best phase for development of these metabolites was the stationary phase; however, in enriched media supplemented with glycerol and mannitol, less antimicrobial activity was observed than that with minimal salts medium supplemented with glucose, since in the latter, five strains were susceptible. Additionally, as the growth curve advanced, the generated metabolites were specific for one microorganism and lost activity against others. It was also determined that the MIC of the secondary metabolites generated in minimal salts medium was much lower than that obtained in enriched media supplemented with glycerol and mannitol. The Pseudomonas strain obtained from mining soils is capable of generating specific bioactive metabolites of one microorganism at different stages of growth.

Key words: Phytopathogens, minimal inhibitory concentration, metabolism, biochemical applications, strains.