Derepressed 2-deoxyglucose-resistant mutants of Aspergillus niger with altered hexokinase and acid phosphatase activity in hyperproduction of beta-fructofuranosidase.
Aspergillus niger NRRL330 produces extracellular beta-fructofuranosidase (Ffase), and its production is subject to repression by hexoses in the medium. After ultraviolet mutagenization and selection, seven derepressed mutants resistant to 2-deoxyglucose (2-DG) were isolated on Czapek's minimal medium containing glycerol. One of the mutants, designated DGRA-1, produced higher levels of Ffase. A considerable difference occurred in the mutants with reference to hexokinase and intracellular acid phosphatase activities. The hexokinase activity of the mutant DGRA-1 (0.69 U/mg) was 1.8-fold higher than the wild type (0.38 U/mg). Intracellular acid phosphatase activity of the mutant DGRA-1 (0.83 U/g of mycelia) was twofold higher than that of the wild type (0.42 U/g of mycelia), suggesting that phosphorylation and dephosphorylation steps could attribute to the 2-DG resistance of A. niger. However, additional mutations could account for the increased production of Ffase in the mutant DGRA-1.
Department of Microbial Technology, School of Biological Sciences, Centre for Excellence in Genomic Sciences, Madurai Kamaraj University, 625 021, India.
B
B
Ashokkumar
S R
SR
Senthilkumar
P
P
Gunasekaran
D000135:Acid Phosphatase / Q000378:metabolism*; D001234:Aspergillus niger / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism; D003847:Deoxyglucose / Q000378:metabolism*; D006593:Hexokinase / Q000378:metabolism*; D009154:Mutation; D043324:beta-Fructofuranosidase / Q000235:genetics / Q000378:metabolism*
D003847:Deoxyglucose; D006593:Hexokinase; D000135:Acid Phosphatase; D043324:beta-Fructofuranosidase