Isolation and preliminary characterization of Pichia pinus mutants insensitive to glucose repression.

A new method for the isolation of glucose repression-insensitive mutants in the methylotrophic yeast Pichia pinus was developed. The method is based on screening of small suspension samples derived from 2-deoxyglucose-resistant colonies for alcohol oxidase activity. Alcohol oxidase activity was evaluated by determination of formaldehyde excreted by cells. Mutants with glucose non-repressible alcohol oxidase and catalase synthesis were obtained. All mutants grew poorly on D-xylose compared to the wild type, whereas growth on L-arabinose was similar to the wild type. Changes in the glucose transport system were suggested to be responsible for altered growth characteristics and defective glucose repression.