Transformation of Candida oleophila and survival of a transformant on orange fruit under field conditions

Histidine auxotrophs of wild-type strain I-182 of Candida oleophila, produc ed using ethyl methanesulfonate, were transformed with plasmids containing the HIS3, HIS4 and HIS5 genes of Saccharomyces cerevisiae. Histidine auxotr ophy was complemented by the HIS5 gene of S. cerevisiae. Stability of the t ransformants under non selective conditions and DNA gel-blot analysis sugge sted that the transforming DNA had integrated into the C. oleophila genome. There were no detectable physiological differences between the wild-type a nd the transformants. The biological control ability of C. oleophila was no t affected by the transformation. A genetically marked transformant (with a beta-glucuronidase gene) colonized wounds on oranges, and its population i ncreased under field conditions. The identity of the genetically marked tra nsformant was established by PCR-amplification of a portion of the beta-glu curonidase gene.