Detection of endogenous beta-glucuronidase activity in Aspergillus niger.
An endogenous beta-glucuronidase that hydrolyses the chromogenic substrate 5-bromo-4-chloro-3-indolyl-beta-D-glucuronide (X-gluc) in Aspergillus niger is reported. The activity was induced when the fungus was grown in media containing xylan, but was either very low, or absent, when grown on glucose. Endogenous beta-glucuronidase was primarily located in newly formed hyphae, and was apparent at pH values between 3 and 6. Hydrolysis of X-gluc was sensitive to the inhibitor D-saccharic acid 1,4-lactone and was irreversibly inactivated by heating. The bacterial uid A beta-glucuronidase reporter gene was strongly expressed in the hyphae of transformed A. niger but, in contrast to the endogenous activity, the enzyme was also active at pH 7-8.5. Histochemical localization of uidA expression in A. niger, without interference from the endogenous beta-glucuronidase activity, was achieved by staining at this pH.
Gottschalk
T E
TE
Danisco Biotechnology, Copenhagen K, Denmark.
Nielsen
J E
JE
Rasmussen
P
P
D001234:Aspergillus niger / Q000201:enzymology* / Q000235:genetics; D002863:Chromogenic Compounds; D004926:Escherichia coli / Q000235:genetics; D005798:Genes, Bacterial; D017930:Genes, Reporter; D005965:Glucuronates; D005966:Glucuronidase / Q000235:genetics / Q000378:metabolism*; D007211:Indoles; D010957:Plasmids / Q000235:genetics; D013379:Substrate Specificity; D014170:Transformation, Genetic
D002863:Chromogenic Compounds; D005965:Glucuronates; D007211:Indoles; C092795:5-bromo-4-chloro-3-indolylglucuronide; D005966:Glucuronidase