Candida fennica: enhancement of protoplast formation and fusion

Abstract

Auxotrophic mutants were obtained by exposing Candida fennica FTPT/CCT-8903 to ultraviolet light and treating the cells with nystatin in an enrichment procedure. The mutants were used for protoplast fusion. The highest protoplast regeneration frequency was obtained when cells were treated with 10 mg NovoZym 234/mL in the presence of 0.8 M KCl for 60 min. Fusion frequency was in the range 5.84 × 10−5 to 7.2 × 10−5. Five prototrophic hybrid colonies, designated S9, S15, S17, S18, and S25, were isolated, and their DNA contents were measured. These measurements indicated that the S17 hybrid is haploid, S9 and S18 are polyploid, and S15 and S25 are both aneuploid. Key words: Candida fennica, nystatin, auxotrophic mutants, protoplast fusion.