Optimization and scale-up of α-amylase production by Aspergillus oryzae using solid-state fermentation of edible oil cakes

Abstract

Background Amylases produced by fungi during solid-state fermentation are the most widely used commercial enzymes to meet the ever-increasing demands of the global enzyme market. The use of low-cost substrates to curtail the production cost and reuse solid wastes are seen as viable options for the commercial production of many enzymes. Applications of α-amylases in food, feed, and industrial sectors have increased over the years. Additionally, the demand for processed and ready-to-eat food has increased because of the rapid growth of food-processing industries in developing economies. These factors significantly contribute to the global enzyme market. It is estimated that by the end of 2024, the global α-amylase market would reach USD 320.1 million (Grand View Research Inc., 2016). We produced α-amylase using Aspergillus oryzae and low-cost substrates obtained from edible oil cake, such as groundnut oil cake (GOC), coconut oil cake (COC), sesame oil cake (SOC) by solid-state fermentation. We cultivated the fungus using these nutrient-rich substrates to produce the enzyme. The enzyme was extracted, partially purified, and tested for pH and temperature stability. The effect of pH, incubation period and temperature on α-amylase production using A. oryzae was optimized. Box–Behnken design (BBD) of response surface methodology (RSM) was used to optimize and determine the effects of all process parameters on α-amylase production. The overall cost economics of α-amylase production using a pilot-scale fermenter was also studied. Results The substrate optimization for α-amylase production by the Box–Behnken design of RSM showed GOC as the most suitable substrate for A. oryzae, as evident from its maximum α-amylase production of 9868.12 U/gds. Further optimization of process parameters showed that the initial moisture content of 64%, pH of 4.5, incubation period of 108 h, and temperature of 32.5 °C are optimum conditions for α-amylase production. The production increased by 11.4% (10,994.74 U/gds) by up-scaling and using optimized conditions in a pilot-scale fermenter. The partially purified α-amylase exhibited maximum stability at a pH of 6.0 and a temperature of 55 °C. The overall cost economic studies showed that the partially purified α-amylase could be produced at the rate of Rs. 622/L. Conclusions The process parameters for enhanced α-amylase secretion were analyzed using 3D contour plots by RSM, which showed that contour lines were more oriented toward incubation temperature and pH, having a significant effect (p < 0.05) on the α-amylase activity. The optimized parameters were subsequently employed in a 600 L-pilot-scale fermenter for the α-amylase production. The substrates were rich in nutrients, and supplementation of nutrients was not required. Thus, we have suggested an economically viable process of α-amylase production using a pilot-scale fermenter.

An Alkalothermophilic Amylopullulanase from the Yeast Clavispora lusitaniae ABS7: Purification, Characterization and Potential Application in Laundry Detergent

“…Among hydrolases, amylases produced by fungi are the most widely used commercial enzymes to meet the ever-increasing demands of the global enzyme market. They are widely used in industry and have been of a great interest in the food, detergent, pharmacy, textile, paper, and bioethanol industries [2][3][4]. The global industrial enzymes market should increase to $7.0 billion by 2023 compared to $5.5 billion in 2018 at a compound annual growth rate of 4.9% for the period 2018-2023 [5].…”

Prospective Application ofAspergillusSpecies: Focus on Enzyme Production Strategies, Advances and Challenges

“…In addition to producing fermentable compounds, they also have an antistaling effect in baking bread which advances the retention of the softness of bakery products, increasing the shelf life of these products. These enzymes are also used for the clarification of fruit and veggie juices or beer or for the pretreatment of animal feed to improve the digestibility of fiber [6,[34][35][36][37][38][39][40][41][42][43][44].…”

Aspergillus Hydrophobins: Physicochemical Properties, Biochemical Properties, and Functions in Solid Polymer Degradation

“…Currently, Aspergilli are used as the host microorganisms for production of these compounds owing to their high productivity of proteins and primary and secondary metabolites [ 37 , 38 , 39 , 40 ]. Aspergilli are used for industrial production of a variety of enzymes, such as amylase, cellulase, glucosidase, hemicellulase, lipase, and phytase from Aspergillus oryzae and Aspergillus niger [ 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 ], and low-molecular-weight compounds such as itaconic acid from Aspergillus terreus [ 53 ], citric acid from A. niger [ 54 ], and kojic acid from A. oryzae [ 55 ]. Aspergilli can infect animals or plants, and are important in the medical, food, and agricultural and livestock fields [ 39 , 56 , 57 , 58 , 59 , 60 ].…”