Efeito de frações ultrafiltradas do cultivo de Hansenula wingei no controle de Penicillium expansum e Apergillus ochraceus

Abstract

The Brazil ranks among the four largest producers of fruit, along with China, India and USA. However, the competitiveness of Brazilian fresh fruit in the international market is very vulnerable. This is due to their susceptibility to fungal infection in the field, as well as attack during storage, resulting in significant economic losses. Allied to consumer interest in natural products and healthier is needed more attention on the quality of fresh fruit to be exported due to prolonged exposure to conditions conducive to proliferation of spoilage fungi / mycotoxigenic. So biocontrol using antagonistic yeasts with mphasis on killer strains, due to the low possibility of toxic residues, shown as a relevant alternative to the traditional chemical treatment, decreasing the amount of fungicides used in the treatment of post-harvest fruit. Thus, the objective was to study the biocontrol of Aspergillus ochraceus and Penicillium expansum (filamentous fungi) by antagonistic yeast Hansenula wingei (AM2 2). Yeast H. wingei showed positive killer against sensitive yeasts Candida glabrata NCYC 366 (K3), Candida albicans 12A (K8) and Pichia kluyveri (CAY-15). In vitro antifungal susceptibility in liquid (broth MPL) the culture supernatant of H. wingei (AM2-2) (25° C for 96 hours) 100% inhibited spore germination and hyphal development of P. expansum. With the use of the same yeast against the fungus A. ochraceus observed a reduction in the development of hyphae of 59.26% (25 ° C/120 hours) and inhibition of spore germination of 90.92% (25 ° C/72 hours). The difference in the supernatants obtained from the yeast culture alone and in interaction with the test fungus was significant (P <0.05) in most experiments. When using the fractions filtered to carry out the in vitro antifungal susceptibility liquid medium was observed 75.02% inhibition of the development of hyphae (10kDa membrane) and 90% inhibition of spore germination (5kDa membrane) A. ochraceus, possibly suggesting that the antifungal compounds with higher activity on this fungus have molecular weight between 3 and 10kDa. In relation to the development of hyphae and spores germination of P. expansum total inhibition was observed (100%) with the use of all fractions, thus suggesting that the antifungal compound of greater activity for P. expansum has a molecular weight below 3kDa. According to the obtained results, it is concluded that the application of antagonistic yeast is a promising tool for the biological control of P. expansum and A. ochraceus in postharvest fruit.