Production of Lipases by a Newly Isolate of Aspergillus niger Using Agroindustrial Wastes by Solid State Fermentation

Abstract

Background: Lipases are enzymes widely used in many industrial applications. However, its use can be increased by reducing costs of production, being important to this effort the screening of new microorganisms producing and the use of low cost culture mediums, such as agricultural residuals. Objective: To produce lipases using two new isolates of filamentous fungi in solid-state fermentation. Methods: The selection of significant variables on the lipase production was studied through a 27-3 Fractional Factorial Design. The studied variables were: the type of bran used as support in solid state fermentation (wheat or soy), nitrogen source (urea or nitrate), inducer (soy or olive oil), nitrogen source concentration (1 or 3%), inducer concentration (1 or 3%), pH (5 or 7) and filamentous fungal strain (Aspergillus O-4 or Aspergillus E-6). Also, a 24 Full Factorial Design was used in the sequence of optimization. Results: The first experimental design showed that the variables type of bran, nitrogen source, inducer, and pH were the most significant (p<0.05) on lipolytic activity, being the higher activity obtained of 45.95 U.g-1. These variables were studied in the second experimental design, in which high lipolytic activities were obtained (57 U) with soy bran, sodium nitrate as nitrogen source, olive oil as inducer and pH 5. Conclusion: The statistical methods of optimization enabled an increased lipase production in solidstate fermentation from Aspergillus niger (O-4). Keywords: Inducer, nitrogen source, pH, response surface methodology, valuation of residuals, fermentation.