Identification and characterization of epiphytic yeasts on apples in China
Currently, little is known regarding the prevalence and diversity of epiphytic yeasts on apples. Therefore, in this study we attempted to identify and characterize yeasts on apples for their potential cider-making performance. A total of 754 yeast strains were isolated from the skins of apples collected from eight provinces in the two main ecological regions of China, i.e., the Loess Plateau and Bo Hai Gulf regions. More than 71 species belonging to 24 genera were identified and Aureobasidium (A.) pullulans and Hanseniaspora (H.) uvarum were the most predominant yeast species. We did not observe any Saccharomyces cerevisiae strains on the associated apple samples. Correspondence analysis revealed the following connection between yeast genera and the provinces: Hanseniaspora in Shaanxi, Rhodotorula in Liaoning, Candida in Shandong, Aureobasidium in Shanxi and Pichia in Hebei. No dominant genera were observed in apples from Gansu, Henan and Ningxia. Although genetic differences among the 23 H. uvarum strains were identified, there was no clear link between the isolates as to origin, genotype and phenotype following RAPD-PCR analysis and some qualitative evaluation of the yeast biochemical activities.