Production and Characterization of Lipases from Aspergillus flavus Isolated from a Soil Sample of the Amazon Rainforest

Abstract

Lipases (E.C.3.1.1.3) hydrolyze triglycerides producing fatty acids and glycerol and can be produced by animals, plants and microorganisms. These enzymes are used in the food industry, biofuels, waste treatment, cosmetics and fine chemicals. Due to the great diversity of microorganisms in the Amazon rainforest and the fact that little is known about them, the present study aimed to produce and characterize lipases from fungi isolated from soil samples from the Amazon rainforest. Therefore, initially the six isolates belonging to the Collection of Microorganisms of Medical Interest at INPA were identified at the genus level by micromorphological analysis. Submerged bioprocesses were performed to determine the best lipase producer. Sequencing of the ITS region of the rDNA was performed to identify the isolate highlighted in the production of lipases. Univariate experiments were carried out studying the influence of carbon sources, nitrogen, initial pH, agitation, and inoculum size on the production of lipases by the isolated isolate. Finally, the enzymes produced were submitted to semi-purification and determination of their optimal temperature, optimal pH and thermal stability. As a result, the six isolates were identified at the genus level, five of which belonged to the Aspergillus genus and one to the Penicillium genus. The isolate highlighted in the lipase production screening was Aspergillus flavus INPA 83. The most suitable culture conditions to produce lipases by Aspergillus flavus INPA 83 were: soybean oil as carbon source, yeast extract as nitrogen source, pH initial temperature between 6 and 8, orbital agitation of 100 rpm and inoculum size between 103 and 106 cells/mL. The lipases showed optimal temperature between 40 oC and 50 oC, optimal pH between 6 and 7 and thermal stability of 72% after 24 hours of incubation at 30 oC. In view of the above results, it was concluded that Aspergillus flavus INPA 83 is a potential Amazonian source of lipases, the latter being a potential bioproduct for the bioeconomy development strategies in the Amazon.