Effect of chitin on the antagonistic activity of Cryptococcus laurentii against Penicillium expansum in pear fruit

This study was designed to evaluate the impact of chitin on the antagonistic activity of Cryptococcus laurentii against the postharvest blue mold rot caused by Penicillium expansum in pear fruit. The results showed that the antagonistic activity of C. laurentii obtained from the culture media of nutrient yeast dextrose broth (NYDB) amended with chitin at 0.5-1.0% was improved greatly compared with the case that without chitin. The addition of chitin to NYDB did not influence the growth of C. laurentii, however, its population was found to increase rapidly thereafter in pear fruit wounds compared to that harvested from NYDB without chitin. Moreover, the cell-free filtrate of the chitin-supplement culture media in which the yeast was incubated for 24 h emerged a direct antifungal activity against P. expansum in pear fruit wounds, with the associated high level of chitinase activity. These results suggested that the use of chitin may be an effective method to induce the antagonistic activity of C. laurentii. To our knowledge, this is the first report regarding the chitin could enhance the efficacy of postharvest biocontrol yeasts.