Han-Chul Yang

Isolation of L-methionine-enriched mutant of a methylotrophic yeast, Candida boidinii No.2201

Abstract Six strains of methylotrophic yeast were examined for production of l -methionine-enriched cells. Candida biodinii ( Kloeckera sp.) No. 2201, which accumulated 0.54 mg/g-dry cell weight (DCW) of free l -methionine (pool methionine), was selected as the parental strain for breeding l -methionine-rich mutants. Ethionine-resistant mutants were derived from the strain by UV irradation. A mutant strain, E500-78, which was resistant to 500 μg/ml of dl -ethionine, accumated 6.02 mg/g-DCW of pool methionine. The culture conditions for mutant strain E500-78 to increase pool methionine accumulation were o-ptimized. As a result, the mutant strain accumulated 8.80 mg/g-DCW of pool methionine and contained 16.02 mg/g-DCW total methionine.

Egg Yolk antibody and its application

A hen transfers her serum immumnoglobulin G to the egg yolk (IgY) and gives im|munity to her offspring. Therefore, the hen egg can be an effective supplier of a large amount of antigen specific antibody that accumulates in the egg yolk. Antigen specific antibody has been widely used for immunological analysis in the field of diagnosis as well as pure scientific research. The production and separation technology of IgY is demonstrated in the present study.

Biochemical Characterization of an L-Methionine-Enriched Mutant of a Methylotrophic Yeast, Candida boidinii

Abstract The effects of an ethionine-resistant mutation in a methylotrophic yeast, Candida boidinii , were studied. In mutant strain E500-78 (ethionine-resistant), SAM synthetase activity was low and was only slightly repressed by l -methionine. Formyltetrahydrofolate synthetase and serine hydroxymethyltransferase were involved in synthesis of the methyl group of l -methionine. The activities of the methyl group transferring enzymes and homocysteine transmethylation were repressed by l -methionine in the wild type strain, but not in the mutant. The activities of the methyl group transferring enzymes were markedly stimulated when the mutant was grown in methanol medium.