PROTOPLAST FUSION AND GENE TRANSFER FOR SACCHAROMYCES SEREVISIAEIMPROVEMENT

Abstract

Lactose is a disaccharide existed at high concentration in whey, the by-product of cheese manufacture. Disposal of whey is a continuing and growing problem in dairy industry.

This study aimed to construct genetically yeast strain capable to utilize lactose either via genetic transformation or by protoplast fusion techniques.

The results obtained can be summarized as follows :

1- Passing the high molecular weight DNA through a 20 G syring­ needle 50 times was efficient in producing DNA fragments from 1 to 4 kb in length.

2- Non lactose-utilizer, S. cerevislae transformant, was obtained when the intact yeast cells were used, while protoplast mediated transformation was able to induce one transformant, named - S.cerevisiae LK 70.

3- S. cerevls/ae LK 70 was able to assimilate lactose and had

-galactosidase activity that liberated 43 J.1 mol glucose I I /107 cells after 24 hours of incubation with lactose buffer.