Nisin enhancement of biocontrol of postharvest diseases of apple with Candida oleophila

Nisin, a polypeptide antibiotic, enhanced the effectiveness of the biocontrol agent Candida oleophila in controlling apple rot caused by Botrytis cinerea and Penicillium expansum. Apples wounds were inoculated with a suspension of the pathogen, antagonist, and nisin in various combinations. At 23 degrees C after 7 days incubation, 4.7% of the wounds developed rot caused by B. cinerea and P. expansum when 0.4% nisin was added to the antagonist suspension, while 33.4% of the fruit developed rot with the antagonist alone. For water control treatments, 100 and 76.2% of the wounds developed rot by B. cinerea and P. expansum, respectively. Nisin enhanced the antagonistic activity of C. oleophila populations in Petri dishes and in the wounds of apples. It inhibited spore germination of bath B. cinerea and P. expansum and restricted the growth of germ tubes which favored the antagonist C. oleophila and thus enhanced biocontrol.