Hydrolysis of lactose by ?-galactosidase immobilized in polyvinylalcohol

Enhancement of β-galactosidase catalytic activity and stability through covalent immobilization onto alginate/tea waste beads and evaluating its impact on the quality of some dairy products

The current study aimed to evaluate the hydrolysis of whole fat milk (WFM) and sweet whey (SW) using β-galactosidase (β-gal) after covalent immobilization onto activated alginate/tea waste (Alg/TW) beads as a novel carrier. The optimum temperature for free and Alg/TW/β-gal was 40 °C and the ideal pH was 7.0. However, Alg/TW/β-gal displayed better stabilities at high temperatures and a wide pH range. Additionally, the value of Km and Vmax for Alg/TW/β-gal was higher than the free enzyme. The Alg/TW/β-gal showed better residual activity (78.6 %) after 90 storage days at 4 °C. The reusability of Alg/TW/β-gal was very good as it conserved its full activity after 15 consecutive cycles and conserved 93 % of its initial activity after 10 cycles with ONPG (O-nitrophenyl-β-D-galactopyranoside) and lactose as a substrate, respectively. The impact of Alg/TW/β-gal on WFM and SW using HPLC analysis revealed a remarkable decrease in lactose concentration and increase of glucose and galactose concentrations. The SW exhibited higher degree of lactose hydrolysis (97.3 %) compared to WFM (62.4 %). Besides, SW had a prominent increase in total phenolic content (96.8 mg/L) compared to WFM (54.3 mg/L). The antioxidant activity had increased after enzyme treatment in both WFM and SW. The GC-MS analysis for volatile compounds identified twenty-five flavour constituents. Finally, Alg/TW/β-gal has a potential application for obtaining healthy, acceptable, and commercial dairy products of low lactose.

Biochemical Insights into a Novel Family 2 Glycoside Hydrolase with Both β-1,3-Galactosidase and β-1,4-Galactosidase Activity from the Arctic

A novel GH2 (glycoside hydrolase family 2) β-galactosidase from Marinomonas sp. BSi20584 was successfully expressed in E. coli with a stable soluble form. The recombinant enzyme (rMaBGA) was purified to electrophoretic homogeneity and characterized extensively. The specific activity of purified rMaBGA was determined as 96.827 U mg-1 at 30 °C using ONPG (o-nitrophenyl-β-D-galactopyranoside) as a substrate. The optimum pH and temperature of rMaBGA was measured as 7.0 and 50 °C, respectively. The activity of rMaBGA was significantly enhanced by some divalent cations including Zn2+, Mg2+ and Ni2+, but inhibited by EDTA, suggesting that some divalent cations might play important roles in the catalytic process of rMaBGA. Although the enzyme was derived from a cold-adapted strain, it still showed considerable stability against various physical and chemical elements. Moreover, rMaBGA exhibited activity both toward Galβ-(1,3)-GlcNAc and Galβ-(1,4)-GlcNAc, which is a relatively rare occurrence in GH2 β-galactosidase. The results showed that two domains in the C-terminal region might be contributed to the β-1,3-galactosidase activity of rMaBGA. On account of its fine features, this enzyme is a promising candidate for the industrial application of β-galactosidase.

Enzyme Immobilization Technologies and Industrial Applications

Enzymes play vital roles in diverse industrial sectors and are essential components of many industrial products. Immobilized enzymes possess higher resistance to environmental changes and can be recovered/recycled easily when compared to the free forms. The primary benefit of immobilization is protecting the enzymes from the harsh environmental conditions (e.g., elevated temperatures, extreme pH values, etc.). The immobilized enzymes can be utilized in various large-scale industries, e.g., medical, food, detergent, textile, and pharmaceutical industries, besides being used in water treatment plants. According to the required application, a suitable enzyme immobilization technique and suitable carrier materials are chosen. Enzyme immobilization techniques involve covalent binding, encapsulation, entrapment, adsorption, etc. This review mainly covers enzyme immobilization by various techniques and their usage in different industrial applications starting from 1992 until 2022. It also focuses on the multiscale operation of immobilized enzymes to maximize yields of certain products. Lastly, the severe consequence of the COVID-19 pandemic on global enzyme production is briefly discussed.

A Review on Psychrophilic β-D-Galactosidases and Their Potential Applications

The majority of the Earth's ecosystem is frigid and frozen, which permits a vast range of microbial life forms to thrive by triggering physiological responses that allow them to survive in cold and frozen settings. The apparent biotechnology value of these cold-adapted enzymes has been targeted. Enzymes' market size was around USD 6.3 billion in 2017 and will witness growth at around 6.8% CAGR up to 2024 owing to shifting consumer preferences towards packaged and processed foods due to the rising awareness pertaining to food safety and security reported by Global Market Insights (Report ID-GMI 743). Various firms are looking for innovative psychrophilic enzymes in order to construct more effective biochemical pathways with shorter reaction times, use less energy, and are ecologically acceptable. D-Galactosidase catalyzes the hydrolysis of the glycosidic oxygen link between the terminal non-reducing D-galactoside unit and the glycoside molecule. At refrigerated temperature, the stable structure of psychrophile enzymes adjusts for the reduced kinetic energy. It may be beneficial in a wide variety of activities such as pasteurization of food, conversion of biomass, biological role of biomolecules, ambient biosensors, and phytoremediation. Recently, psychrophile enzymes are also used in claning the contact lens. β-D-Galactosidases have been identified and extracted from yeasts, fungi, bacteria, and plants. Conventional (hydrolyzing activity) and nonconventional (non-hydrolytic activity) applications are available for these enzymes due to its transgalactosylation activity which produce high value-added oligosaccharides. This review content will offer new perspectives on cold-active β-galactosidases, their source, structure, stability, and application.

Sources of β-galactosidase and its applications in food industry

The enzyme β-galactosidases have been isolated from various sources such as bacteria, fungi, yeast, vegetables, and recombinant sources. This enzyme holds importance due to its wide applications in food industries to manufacture lactose-hydrolyzed products for lactose-intolerant people and the formation of glycosylated products. Absorption of undigested lactose in small intestine requires the activity of this enzyme; hence, the deficiency of this enzyme leads to lactose intolerance. Lactose intolerance affects around 70% of world's adult population, while the prevalence rate of lactose intolerance is 60% in Pakistan. β-Galactosidases are not only used to manufacture lactose-free products but also employed to treat whey, and used in prebiotics. This review focuses on various sources of β-galactosidase and highlights the importance of β-galactosidases in food industries.

Potential Applications of Immobilized β-Galactosidase in Food Processing Industries

The enzyme β-galactosidase can be obtained from a wide variety of sources such as microorganisms, plants, and animals. The use of β-galactosidase for the hydrolysis of lactose in milk and whey is one of the promising enzymatic applications in food and dairy processing industries. The enzyme can be used in either soluble or immobilized forms but the soluble enzyme can be used only for batch processes and the immobilized form has the advantage of being used in batch wise as well as in continuous operation. Immobilization has been found to be convenient method to make enzyme thermostable and to prevent the loss of enzyme activity. This review has been focused on the different types of techniques used for the immobilization of β-galactosidase and its potential applications in food industry.

Glucose oxidase sandwiched between pHEMA layers: a continuous flow reactor application

Glucose oxidase was entrapped between poly(2-hydroxyethyl methacrylate) membranes and conditions were optimized for high enzyme activity and high levels of entrapment. Highest entrapment was with a 78 microns thick coat. A continuous flow membrane reactor was designed and used. The reaction was first order with respect to glucose and to oxygen. Vmax values for the native and immobilized enzymes were 0.182 and 0.133 mM/min. The Km's for native and immobilized enzymes were 6.2 and 16.9 mM, respectively. At high substrate concentrations enzyme poisoning was detected. Both pH and temperature profiles moved to higher values upon immobilization. The enzyme retained 80% of its activity for at least 3 months in dry form.