UTILIZATION OF GALACTOSE BY ASPERGILLUS NIGER AND PENICILLIUM GLAUCUM

Publisher Website
Google Scholar
Abstract
A. niger and P. glaucum were grown on liquid media containing dextrose, levulose, galactose or mannose and on mixtures of these sugars with a total sugar content of 2% in each case. Galactose and mannose were poor C sources for both organisms. Galactose also retarded the rate of spore germination and mycelium growth of A. niger, and caused the production of crooked, much-branched mycelium such as is produced in the presence of toxins. When galactose was mixed with levulose, dextrose or mannose, there was an acceleration in the growth rate and an increase in the amount of dry matter produced by both organisms. With galactose + dextrose there were 2 optimum mixtures for A. niger the 1st optimum was on 1% galactose+ 1% dextrose and the 2d on 0.4% galactose+ 1.6% dextrose; for P. glaucum, the 1st optimum was on 1.6% galactose + 0.4% dextrose and the 2d on 0.6% galactose+1.4% dextrose. Mixtures of dextrose, levulose and mannose produced no acceleration. This was also the case when sucrose and lactose were mixed. Preliminary tests indicate that the acid produced in the culture medium does not cause this acceleration and tests on sterilization by filtration showed that it was not due to any effect of heat on the sugars in the mixtures.