Influence of carbon source on alpha-amylase production by Aspergillus oryzae

The influence of the carbon source on a-amylase production by Aspergillus o ryzae was quantified in carbon-limited chemostat cultures. The following ca rbon sources were investigated: maltose, maltodextrin (different chain leng ths), glucose, fructose, galactose, sucrose, glycerol, mannitol and acetate . A. oryzae did not grow on galactose as the sole carbon source, but galact ose was co-metabolized together with glucose. Relative to that on low gluco se concentration (below 10 mg/l), productivity was found to be higher durin g growth on maltose and maltodextrins, whereas it was lower during growth o n sucrose, fructose, glycerol, mannitol and acetate. During growth on aceta te there was no production of alpha -amylase, whereas addition of small amo unts of glucose resulted in alpha -amylase production. A possible induction by alpha -methyl-D-glucoside during growth on glucose was also investigate d, but this compound was not found to be a better inducer of alpha -amylase production than glucose. The results strongly indicate that besides acting as a repressor via the CreA protein, glucose acts as an inducer.