SILENCING MIG1 IN SACCHAROMYCES-CEREVISIAE - EFFECTS OF ANTISENSE MIG1 EXPRESSION AND MIG1 GENE DISRUPTION

Silencing of MIG1, a transcription factor imposing carbon catabolite r epression on invertase was attempted, either by disrupting the gene or by expressing antisense copies of the gene. The performance of the re combinant strains in bioreactor batch cultivations on sucrose, in the presence of glucose, was compared with that of the wild-type strain un der the same conditions, In the Delta mig1 strain, the rate of sucrose utilization was independent (10 mmol/g/h) of the glucose concentratio n. During the cultivations with the wild-type strain and the antisense strains, two distinct phases were observed. The rates of sucrose hydr olysis were <1 mmol/g/h and 9 to 10 mmol/g/h in the first and second p hases, respectively. Entry into the second cultivation phase was chara cterized by a decline in glucose concentration below 12 mmol/liter. As expected, disruption of MIG1 resulted in a relief of glucose repressi on, However, silencing of MIG1 expression was not achieved by expressi ng antisense MIG1, even though antisense MIG1 RNA was sufficiently sta ble to be detected. In the wild-type and Delta mig1 strains, the speci fic growth rate was 0.32 to 0.33 h(-1), whereas it was lower in the an tisense strains, 0.25 to 0.30 h(-1).