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Recent Advancement in Microbial Enzymes and Their Industrial Applications
Published in Pankaj Bhatt, Industrial Applications of Microbial Enzymes, 2023
Pankaj Bhatt, Sajjad Ahmad, Samiksha Joshi, Kalpana Bhatt
Dairy enzymes provide a high yield and improve color, flavor, and aroma. Several enzymes, like lipases, catalase, proteases, esterases, aminopeptidase, lactoperoxidase, lysozyme, transglutaminase, and lactase, are of significant use in the dairy market. They function as coagulants and bio-protective enzymes for the prolonged shelf life of dairy products. Production of cheese, yogurt, and other customized milk products is done with dairy enzymes, such as microbial rennet, proteases, and lipases (Qureshi et al., 2015). Rennet, made up of pepsin and chymosin, aids in milk coagulation into solid curds for the production of cheese and liquid whey. Currently, about 33% of cheese production at the global level is done using microbial rennet (Qureshi et al., 2015). Some microbial producers of rennet-like proteases are Rhizomucor pusillus, Irpex lactis, A. oryzae, Endothia parasitica, and Rhizopus miehei (Qureshi et al., 2015). Degradation of casein by plasmin results in proteolysis that can be either detrimental or beneficial depending on the type of product and level of hydrolysis. For example, proteolysis can provide the required texture and flavor in cheese-making and also can result in unwanted gelation in pasteurized milk and milk processed at ultra-high temperature. Enzymes produced by psychrotrophic microbes can cause this kind of proteolysis during the refrigeration of milk. Lactic acid bacteria are commonly used as a starter culture for curd production. These bacteria are a rich source of peptidases and proteases as they require them for fast growth in milk (dos Santos Mathias et al., 2017). Protease enzymes obtained from members of genera Lactococcus, Streptococcus, and Lactobacillus help in the breakdown of major milk allergens, like β-lactoglobulin and α-lactalbumin (Atanasova et al., 2014). In the dairy industry, lipases are employed for milk fat hydrolysis, quick cheese production, and flavor enhancement. Lipases derived from Aspergillus oryzae, Rhizomucor miehei, and Aspergillus niger play an important role in the cheese-making process. Transglutaminase catalyzes milk protein polymerization, which enhances the functional qualities of dairy products (Kieliszek and Misiewicz, 2014). Glucose oxidases help in cheese and curd formation (Pal et al., 2016). Lactase-producing microbes, such as Neurospora sp., Streptococcus sp., Bacillus sp., Mucor sp., E. coli, Lactobacillus sp., Aspergillus sp., Kluyveromyces sp., and Candida sp. (Nivetha et al., 2017) are used to make prebiotics, lactose-hydrolyzed milk products, and whey in the dairy industry (Singh et al., 2019). The β-galactosidase enzyme helps in the catalytic breakdown of lactose to galactose and glucose and therefore works as a digestive aid in lactose-intolerant patients (Qureshi et al., 2015). Aspartate-producing bacterium Propionibacterium sp. is also used for Swiss cheese production. Invertase enzyme obtained from Saccharomyces carlsbergensis and Saccharomyces cerevisiae are used to commercially synthesize invert sugar, utilized as a sweetener in dairy products.
Enzymatic crosslinking of silk sericin through combined use of TGase and the custom peptide
Published in The Journal of The Textile Institute, 2020
Xiaoxiao Guo, Qian Zhou, Ping Wang, Yuanyuan Yu, Jiugang Yuan, Qiang Wang
As a transferred enzyme, transglutaminase (TGase, EC 2.3.2.13) can catalyze the acyl-transfer reaction between the γ-carboxyamide group of glutamine (acyl receptor) and the ε-amino group of lysine (acyl donor), resulting in the formations of ε-(γ-glutamyl)-lysine crosslinks (Cui et al., 2017). TGases have been used to build intermolecular and intramolecular connections in diverse protein materials, such as soy protein isolate (Jiang, Tang, Wen, Li, & Yang, 2009), gelatin (Piotrowska, Sztuka, Kołodziejska, & Dobrosielska, 2008), myofibrillar proteins (Hong & Xiong, 2012), and milk proteins (Bönisch, Huss, Weitl, & Kulozik, 2007). For the substrate of sericin protein, it contains glutamate (some of which is located in the form of glutamine), lysine (Wu, Wang, & Xu, 2007), and free amino groups at the end of molecular chains (Cao & Zhang, 2016). These characteristic structures in SS can be catalyzed by TGase, which provides a novel enzymatic approach for reducing water solubility of SS. On the other hand, the efficacy of TGase-mediated reaction highly depends on the amount of glutamine and amino groups contained in SS, which will affect the performances of the regenerated sericin materials.
Isolation, screening, and optimization of bacterial strains for novel transglutaminase production
Published in Preparative Biochemistry and Biotechnology, 2019
Karuna L. Sorde, Laxmi Ananthanarayan
Transglutaminases (TGase) are a class of hydrolases known to cross-link proteins. Transglutaminases (EC 2.3.2.13) catalyze the formation of an amide bond between a free amine group and the γ-carboxamide group of protein-bound glutamine, lysine, and various primary amines. They have the ability to crosslink proteins fractions of whey, soy, wheat, rice protein, and fish and meat protein changing their physical and chemical properties such as appearance, solubility, texture, elasticity, thermal stability, and resilience of protein leading to improvement in the functional properties of food.[1]
Novel approaches based on ultrasound for spray drying of food and bioactive compounds
Published in Drying Technology, 2021
Rajeshree A. Khaire, Parag R. Gogate
Further, for temperature sensitive materials, ultrasonic spray freeze drying (USFD) process was considered as an effective approach for microencapsulation[1,52,53] and it was reported that the combination of ultrasonic atomization with spray freeze drying (SFD) resulted in an enhanced control over the particle properties.[54] To understand the thermal stability of microencapsulated products, Isleroglu and Turker[55] studied the microencapsulation of transglutaminase using ultrasonic SFD. Transglutaminase has found wide applications in the dairy and bakery industries as a binding agent, to enhance the properties of cheese and to improve the texture of bakery products as well.[56,57] Ultrasonic nozzle of 48 kHz frequency was used for atomization of feed solution at a feed flowrate of 6.83 mL/min, 7 cm above the surface of liquid nitrogen for rapid freezing. The remaining liquid nitrogen was evaporated and the resulting pellet was stored at −35 °C temperature in a freeze dryer. The frozen product was further dried for 12 h at 1 mbar pressure followed by drying for 4 h at 0.01 mbar pressure and 30 °C shelf temperature. The results were compared with conventional spray drying and freeze drying. In the case of spray drying, same feed solution was sprayed at the same flowrate in a laboratory scale spray dryer with inlet temperature of 150 °C and outlet temperature of 79 °C. Similarly, in the case of conventional freeze drying approach, the solution was frozen for 4 h at −80 °C and then transferred to the same freezer following the same steps of drying as USFD. It was clearly demonstrated that better thermal stability is obtained using USFD. Overall, USFD was reported to be a better technique providing high thermally stable dried microencapsulated particles with lower processing times than the conventional freeze-drying approach.