Aspergillus niger LMM01: A new source of glucose oxidase in Amazon

Glucose oxidase (GOx) has several industrial applications. It is believed that there are several species of fungi that have the ability to produce this enzyme, most of which are unexplored. This work aimed to investigate the production of glucose oxidase (EC 1.1.3.4) by fungi isolated from soil samples of the Amazonian forest. Filamentous fungi were isolated from soil samples from the Adolpho Ducke Forest Reserve, located in Manaus, Amazonas. Strains were subjected to submerged bioprocessing to select for the best GOx producers. Those selected for the production of isolated enzymes were subjected to kinetic tests that evaluated production of the enzyme and consumption of the biomass substrate by the isolates. In addition, experiments to evaluate the optimal carbon, nitrogen and phosphorus sources as well as the influence of the bioprocess factors were carried out. Finally, GOx production was investigated in a semi-continuous system for 7 days. The most frequent isolates isolated from soil samples belonged to the genera Aspergillus, Penicillium and Trichoderma. Aspergillus niger LMM01 was the best GOx producer. Glucose, peptone and KH2PO4 were demonstrated to be the optimal carbon, nitrogen and phosphorus sources, respectively. Multivariate experiments demonstrated that the parameters with the greatest effect on GOx production were pH and agitation. Stable expression results for GOx (7.74 U/ml) were obtained over 7 days in a semi-continuous process. In this context, the new Amazonian source of this enzyme (A. niger LMM01), and enzyme production in a semi-continuous process, demonstrates the importance of the present work.   Key words: Amazon, fungi, production, glucose oxidase.