Biological control of post-harvest anthracnose rot of loquat fruit by Pichia membranefaciens

The effect of Pichia membranefaciens on reducing post-harvest anthracnose rot caused by Colletotrichum acutatum in loquat fruit was investigated. Fruit were treated with different suspensions of P. membranefaciens before challenge with 1.0 X 10(5) spores ml(-1) of C acutatum, then incubated at 20 degrees C for 6 d. The results showed that 1 X 10(8) colony-forming units (CFU) ml(-1) of washed cell suspensions of the yeast provided better control of anthracnose rot than yeast in culture broth at the same concentration. Treatment with autoclaved cell cultures or culture filtrates did not prevent the incidence of disease. The concentration of a washed cell suspension of P. membranefaciens had a significant effect on the efficacy of controlling anthracnose rot in loquat fruit. At a concentration range from 1 X 10(6) to 1 X 10(9) CFU ml(-1), the higher the concentration of the antagonist, the lower the incidence of the disease and the smaller the diameter of the lesions. In inoculated wounds of loquat fruit, populations of P. membranefaciens increased approx. 34-fold after 6 d of incubation at 20 degrees C. Washed cell suspensions of P. membranefaciens also significantly inhibited spore germination and germ-tube growth of C. acutatum, in vitro. These results suggest that P. membranefaciens has potential as a biocontrol agent to reduce post-harvest decay caused by C. acutatum in loquat fruit.