Abstract
Lipases are triacylglycerol hydrolases that catalyze hydrolysis, esterification, interesterification, and transesterification reactions. These enzymes are targets of several industrial and biotech applications, such as catalysts, detergent production, food, biofuels, wastewater treatment, and others. Microbial enzymes are preferable for large scale production due to ease of production and extraction. Several studies have reported that lipases from filamentous fungi are predominantly extracellular and highly active. However, there are many factors that interfere with enzyme production (pH, temperature, medium composition, agitation, aeration, inducer type, and concentration, etc.), making control difficult and burdening the process. This work aimed to optimize the lipase production of four fungal isolates from oily residues (Penicillium sp., Aspergillus niger, Aspergillus sp., and Aspergillus sp.). The lipase-producing fungi isolates were morphologically characterized by optical and scanning electron microscopy. The optimal lipase production time curve was previously determined, and the response variable used was the amount of total protein in the medium after cultivation by submerged fermentation. A complete factorial design 32 was performed, evaluating the temperatures (28 °C, 32 °C, and 36 °C) and soybean oil inducer concentration (2%, 6%, and 10%). Each lipase-producing isolate reacted differently to the conditions tested, the Aspergillus sp. F18 reached maximum lipase production, compared to others, under conditions of 32 °C and 2% of oil with a yield of 11,007 (µg mL−1). Penicillium sp. F04 achieved better results at 36 °C and 6% oil, although for Aspergillus niger F16 was at 36 °C and 10% oil and Aspergillus sp. F21 at 32 °C and 2% oil. These results show that microorganisms isolated from oily residues derived from environmental sanitation can be a promising alternative for the large-scale production of lipases.Graphical
Highlights
The enzymatic process is only one field among many more in biotechnology, it has wide applications that are often promising alternatives when it comes to replacing conventional methodologies [1]
Morphological characterization The fungal isolates used in this work were obtained from grease boxes and soils in which oily residues were found
The factorial design using the variables temperature and concentration of the inducer enabled the optimization of lipases production
Summary
The enzymatic process is only one field among many more in biotechnology, it has wide applications that are often promising alternatives when it comes to replacing conventional methodologies [1]. Lipases (triacylglycerol acyl-hydrolases, EC 3.1.1.3) are enzymes with a natural role of hydrolyzing triacylglycerol (TAG) into glycerol and free fatty acids, as well as catalyzing the esterification and transesterification reactions [4, 5] These very same enzymes play an important role in the degradation of natural materials, industrial pollutants, and other toxic products, due to two of their properties: regioselectivity and enantioselectivity [5]. From an economic and industrial standpoint, lipases obtained from microorganisms through the fermentation process are preferable over their animal and plant counterparts [10], given both its high yield in a relatively short amount of time and the lower costs associated with the raw materials [11] Another economic impact is that Brazil has great potential for enzyme production because of its great biodiversity of producing organisms, even though clearly spending more on imported products [12]
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