Purification, biochemical characterization, and biotechnological applications of a multifunctional enzyme from the Thermoascus aurantiacus PI3S3 strain

The filamentous Thermoascus aurantiacus fungus characterized by its thermophilic nature, is recognized as an exceptional producer of various enzymes with biotechnological applications. This study aimed to explore biotechnological applications using polygalacturonase (PG) derived from the Thermoascus aurantiacus PI3S3 strain. PG production was achieved through submerged fermentation and subsequent purification via ion-exchange chromatography and gel filtration methods. The crude extract exhibited a diverse spectrum of enzymatic activities including amylase, cellulase, invertase, pectinase, and xylanase. Notably, it demonstrated the ability to hydrolyze sugarcane bagasse biomass, corn residue, and animal feed. The purified PG had a molecular mass of 36 kDa, with optimal activity observed at pH 4.5 and 70 °C. The activation energy (Ea) was calculated as 0.513 kJ mol-1, highlighting activation in the presence of Ca2+. Additionally, it displayed apparent Km, Vmax, and Kcat values of at 0.19 mg mL-1, 273.10 U mL-1, and 168.52 s-1, respectively, for hydrolyzing polygalacturonic acid. This multifunctional PG exhibited activities such as denim biopolishing, apple juice clarification, and demonstrated both endo- and exo-polygalacturonase activities. Furthermore, it displayed versatility by hydrolyzing polygalacturonic acid, carboxymethylcellulose, and xylan. The T. aurantiacus PI3S3 multifunctional polygalacturonase showed heightened activity under acidic pH, elevated temperatures, and in the presence of calcium. Its multifunctional nature distinguished it from other PGs, significantly expanding its potential for diverse biotechnological applications.

Production, immobilization and application of invertase from new wild strain Cunninghamella echinulata PA3S12MM

AIMS

The objective of this study was to determine the best conditions to produce invertase by Cunninghamella echinulata PA3S12MM and to immobilize and apply the enzyme.

METHODS AND RESULTS

The maximum production was verified in 8 days of cultivation at 28°C supplemented with 10 g L^-1 apple peel, reaching 1054.85 U ml^-1 . The invertase was purified from the DEAE-Sephadex column. The derivative immobilized in alginate-gelatin-calcium phosphate showed reusability >50% for 19 cycles. The derivative immobilized in glutaraldehyde-chitosan showed greater thermostability and at a different pH. The hydrolysis of 15 ml of sucrose 500 g L^-1 in a fixed bed reactor (total volume of 31 ml) produced 24.44 µmol min^-1 of glucose and fructose at a residence time of 30 min and a conversion factor of 0.5.

CONCLUSIONS

The new wild strain C. echinulata PA3S12MM presents high invertase production in medium supplemented with an agro-industrial residue and the immobilized enzyme showed high thermal stability and resistance at a different pH.

SIGNIFICANCE AND IMPACT OF THE STUDY

The fungus C. echinulata PA3S12MM is an excellent producer of invertases in Vogel medium supplemented with apple peel. The enzyme is promising for industrial application since it has good performance in reusability and inverted sugar production.

A novel Thermothelomyces heterothallicus PA2S4T fungus isolated from the soil induces chitinase production using orange peel flour

Chitinases are enzymes capable of hydrolysing the β-1,4 bonds of chitin releasing chitooligosaccharides and N-acetylglucosamine and are widely used in food, pharmaceutical, and agricultural industries. Microorganisms are potential producers of this enzyme; however, there are no reports in the literature on the production of chitinase by fungi of the genus Thermothelomyces. Thus, this work aimed to investigate the production of extracellular chitinase using alternative carbon sources by the fungus isolated from soil, Thermothelomyces heterothallicus PA2S4T. The fungus was cultivated in a liquid medium supplemented with carbon sources and incubated at 40°C under stationary conditions for seven days. Orange peel flour was the best inducer for extracellular chitinase, with 82.3 U/mL of enzymatic activity. The highest production of chitinase was obtained on the tenth day, and the optimum pH and temperature for enzyme activity were 4.5 and 50ºC, respectively. Therefore, the fungus T. heterothallicus PA2S4T proved to be promising in the production of extracellular chitinase, which presents pH and temperature characteristics favourable to biotechnological application.

Cunninghamella echinulata PA3S12MM invertase: Biochemical characterization of a promiscuous enzyme

The Cunninghamella echinulata PA3S12MM fungus is a great producer of invertases in a growth medium supplemented by apple peels. The enzyme was purified 4.5 times after two chromatographic processes, and it presented a relative molecular mass of 89.2 kDa. The invertase reached maximum activity at pH of 6 and at 60°C, in addition to presenting stability in alkaline pH and thermal activation at 50°C. The enzymatic activity increased in the presence of Mn²⁺ and dithiothreitol (DTT), while Cu²⁺ and Z²⁺ ions inhibited it. Also, DTT showed to protect enzymatic activity. The apparent values for K_m , V_máx , and K_cat for the sucrose hydrolysis were, respectively, 173.8 mmol/L, 908.7 mmol/L min^-1 , and 1,388.79 s^-1 . The carbohydrate content was of 83.13%. The invertase presented hydrolytic activity over different types of glycosidic bonds, such as α1 ↔ 2β (sucrose), α1 → 4 (polygalacturonic acid), α1 → 4 and α1 → 2 (pectin), and α1 ↔ 1 (trehalose), indicating that the enzyme is multifunctional. Thus, the biochemical properties showed by the C. echinulata PA3S12MM suggest a broad industrial application, such as in the biomass hydrolysis or in the food industry. PRACTICAL APPLICATIONS: Invertases are hydrolytic enzymes employed in several industrial sectors. Given their great importance for the economy and several industrial sectors, there is a growing interest in microorganisms producing this enzyme. The analysis of the biochemical properties of invertase in C. echinulata PA3S12MM suggest applications in the food industry. Due to its increased hydrolytic activity, the hydrolysis process of the sucrose may employ invertase for the production of invert sugar. The stability at alkaline pH suggests an application in the development of enzymatic electrodes for the quantification of sucrose in food and beverage. The multifunctional activity may work in the biomass hydrolysis or saccharification of by-products for the extraction of fermentable sugars. The high level of invertase N-linked glycosylation of invertase grants this enzyme thermal stability at high temperatures, in addition to resistance against the action of proteases, which are desirable characteristics for the application of this enzyme in industrial processes.