Breeding of Yeast for Waste Water Treatment by Protoplast Fusion

Abstract

Breeding of yeast strains for waste water treatment was attempted by protoplast fusion between a flocculent yeast Hansenula anomala J224 and a glucoamylaseproducing strain Hansenula anomala fabianii J640, and five fusants were isolated. These fusants have some common characteristics of parent strains in flocculation and glucoamylase production. Both the flocculation and glucoamylase activity of fusants were about 60% and 60%, respectively, as compared with parent strains. Electrophoretic chromosomal DNA patterns of fusant strains No.3 and No.4 were separated into seven bands in CHEF-DRII system, and six bands of them were similar to those of the parent strain J640, and one of them was similar to a band of the parent strain J224. Treatment test of waste water containing starch by the fusant strain No.4 was made in a 11 jar fermenter at pH 4.8, 25-30°C, BOD loading of yeast tank 3-4. 5g/l. d, and aeration rate O. 5 vvm by stirring at 400 rpm for 24 h. As a result, BOD and TOD in the waste water containing starch were removed by 80 and 70%, respectively.