Controle de fungos deteriorantes / micotoxigênicos por leveduras Killer antagonistas em frutas pós-colheita

Abstract

The biocontrol by antagonist killer yeast is a viable alternative for the traditional chemical, due the low toxigenic possibility and the nonappearance of undesirable residues on the considered fruits. Taking this into account, the aim of this work was to study the biocontrol of spoilage mould by using antagonist yeasts associated to the killer factor, isolated of frozen pulp fruits, through the analysis of antagonism by the production of bioactive compounds, evaluating the inhibition of spoilage mould growth (percentage of germinated spores and the hyphae length). From the 41 isolated yeasts tested, 24 (58,5%) showed inhibition activity against Penicillium expansum n.º 2, 25 (61,0%) were active against Aspergillus ochraceus A152 and 25 (61,0%) against Fusarium verticillioides 103F, by the antifungal susceptibility on solid medium. By the liquid medium technique , strain PF413 (identified as Kluyveromyces sp.), showed significant control of spore germination, as well as of hyphal development of P. expansum e A. ochraceus, when compared to control. The inhibition of P. expansum and A. ochraceus spores germination in the presence of Kluyveromyces sp. PF413 crude extract (96 hs/25oC cultivate), was respectively, 93.33 and 86.44%). The positivity for the killer factor was evidenced in 75.6% of the isolated yeasts. The results reinforce the need of studying antagonists microorganisms with innocuous character, thereby improving the hygienic-sanitary quality and the safety of agroindustrial products.