ANTAGONISM OF NATIVE YEASTS AGAINST BLUE MOULD (Penicillium expansum Link) IN APPLE FRUITS

Abstract

Low quality and inadequate marketing of apple (Malus domestica Borkh) produced in the highlands of Querétaro, México are partly due to an inadequate product storage during which losses ocurr, most of them due to the “blue mould” caused by Penicillium expansum Link. An ecologic alternative for controlling this and other decays is the use of antagonistic yeasts with ability to grow at low temperatures for long periods of time. The antagonistic potential of isolated yeasts against P. expansum was evaluated in vitro and in vivo on apples obtained in Cadereyta, Querétaro. The most effective yeast strains were identified by using the Biolog® system. Strain 16- 212 showed the highest inhibition against P. expansum after 96 h of in vitro incubation (67 %). On fruits experiments in vivo, strains 5vtt and 23-61 showed the highest antagonism. No correlation between the in vitro and in vivo antagonisms was observed (r = 0.11). The Biolog® system allowed the identification of 5-vtt (Candida incommunis), with a similarity index (SI) of 0.72 and 95 % de probability, of 38-432 as Debaryomices hansenii (SI = 0.53) and 35-111 as Cryptococcus albidus (SI = 0.58). Strain 26-224 (Torulaspora spp.) was also identified through specialized handbooks. Biolog® probed to be an efficient method to identify most of the studied yeast strains.