Characterization of SdGA, a cold-adapted glucoamylase from Saccharophagus degradans

Cold-active enzymes from deep marine psychrophiles: harnessing their potential in enhanced food production and sustainability

Exploring the untapped potential of deep-sea microorganisms, particularly their cold-active enzymes, or psychrozymes, offers exciting possibilities for revolutionizing various aspects of the food processing industry. This review focuses on these enzymes, derived from the largely unexplored depths of the deep ocean, where microorganisms have developed unique adaptations to extreme conditions. Psychrozymes, as bioactive molecules, hold significant promise for food industry applications. However, despite their potential, the understanding and industrial utilization of psychrozymes remains limited. This review provides an in-depth analysis of how psychrozymes can: improve processing efficiency, enhance sensory qualities, extend product shelf life, and reduce energy consumption across the food production chain. We explore the cryodefense strategies and cold-adaptation mechanisms that support these enzymes, shedding light on the most extensively studied psychrozymes and assessing their journey from theoretical applications to practical use in food production. The key properties, such as stability, substrate specificity, and catalytic efficiency in cold environments, are also discussed. Although psychrozymes show considerable promise, their large-scale application in the food industry remains largely unexplored. This review emphasizes the need for further research to unlock the full potential of psychrozymes, encouraging their broader integration into the food sector to contribute to more sustainable food production processes.

Extremophilic Microorganisms as a Source of Emerging Enzymes for the Food Industry: A Review

Modern-day consumers are interested in highly nutritious and safe foods with corresponding organoleptic qualities. Such foods are increasingly subjected to various processing techniques which include the use of enzymes. These enzymes like amylases, lipases, proteases, xylanases, laccases, pullulanase, chitinases, pectinases, esterases, isomerases, and dehydrogenases could be derived from extremophilic organisms such as thermophiles, psychrophiles, acidophiles, alkaliphiles, and halophiles. As these organisms can grow under severe environmental conditions, they can produce functional enzymes (extremozymes) used in producing safe foods (such as gluten-free, lactose-free, lower acrylamide, or lower trans-fat products). The extremozymes also enhance nutrient bioavailability and bioaccessibility (e.g., predigested nourishments like baby formulae), and improve nourishment functionalities such as surface, sensory, and bioactive properties. Therefore, exploring alternative sources of enzymes for better compatibility and long-term adaptability in the processing stages is a promising approach for obtaining novel food products. This review will establish novel discovery methods of extremozymes from psychrophiles, thermophiles, acidophiles, alkaliphiles, and halophiles, the enzymes' types, mechanisms of action, and their food applications. It will also contribute to their commercial relevance and the furtherance of their discovery.

Microbial glucoamylases: structural and functional properties and biotechnological uses

Glucoamylases (GAs) are one of the principal groups of enzymes involved in starch hydrolysis and belong to the glycosylhydrolase family. They are classified as exo-amylases due to their ability to hydrolyze α-1,4 glycosidic bonds from the non-reducing end of starch, maltooligosaccharides, and related substrates, releasing β-D-glucose. Structurally, GAs possess a characteristic catalytic domain (CD) with an (α/α)6 fold and exhibit five conserved regions within this domain. The CD may or may not be linked to a non-catalytic domain with variable functions depending on its origin. GAs are versatile enzymes with diverse applications in food, biofuel, bioplastic and other chemical industries. Although fungal GAs are commonly employed for these purposes, they have limitations such as their low thermostability and an acidic pH requirement. Alternatively, GAs derived from prokaryotic organisms are a good option to save costs as they exhibit greater thermostability compared to fungal GAs. Moreover, a group of cold-adapted GAs from psychrophilic organisms demonstrates intriguing properties that make them suitable for application in various industries. This review provides a comprehensive overview of the structural and sequential properties as well as biotechnological applications of GAs in different industrial processes.

The effect of barium and strontium on activity of glucoamylase QsGH97a from Qipengyuania seohaensis SW-135

Glycoside hydrolases (GHs), the enzymes that break glycosidic bonds, are ubiquitous in the ecosystem, where they perform a range of biological functions. As an interesting glycosidase family, Glycoside hydrolase family 97 (GH97) contains α-glucosidase, α-galactosidase, and glucoamylase. Only ten members of GH97 have been characterized so far. It is critical to explore novel members to elucidate the catalytic mechanism and application potential of GH97 family. In this study, a novel glucoamylase QsGH97a from Qipengyuania seohaensis SW-135 was cloned and expressed in E. coli. Sequence analysis and NMR results show that QsGH97a is classified into GH97a, and adopts inverting mechanism. The biochemical characterization indicates that QsGH97a shows the optimal activity at 50 °C and pH 8.0. Ca²⁺ has little effect on the catalytic activity; however, the activity can be substantially increased by 8-13 folds in the presence of Ba²⁺ or Sr²⁺. Additionally, the metal content of QsGH97a assay showed a high proportion of Sr²⁺. The specific metal activity was initially revealed in glucoamylases, which is not found in other members. These results imply that QsGH97a not only is a new member of GH97, but also has potential for industrial applications. Our study reveals that Ba²⁺ or Sr²⁺ may be involved in the catalytic mechanism of glucoamylase, laying the groundwork for a more complete knowledge of GH97 and its possible industrial application.

Identification, molecular and biochemical characterization of a novel thermoactive and thermostable glucoamylase from Thermoanaerobacter ethanolicus

PURPOSE

We identified a new glucoamylase (TeGA) from Thermoanaerobacter ethanolicus, a thermophilic anaerobic bacterium. Structural studies suggest that TeGA belongs to the family 15 of glycosylhydrolases (GH15).

METHODS

The expression of this enzyme was optimized in E. coli (BL21) cells in order to have the highest amount of soluble protein (around 3 mg/l of culture medium).

RESULTS

TeGA showed a high optimum temperature of 75 °C. It also showed one of the highest specific activities reported for a bacterial glucoamylase (75.3 U/mg) and was also stable in a wide pH range (3.0-10.0). Although the enzyme was preferentially active with maltose, it was also able to hydrolyze different soluble starches such as those from potato, corn or rice. TeGA showed a high thermostability up to around 70 °C, which was increased in the presence of PEG8000, and also showed to be stable in the presence of moderate concentrations of ethanol.

CONCLUSION

We propose that TeGA could be suitable for use in different industrial processes such as biofuel production and food processing.

Improving Thermostability of Chimeric Enzymes Generated by Domain Shuffling Between Two Different Original Glucoamylases

In order to improve enzymatic properties of glucoamylases, six recombinant genes GA1–GA6 were created by domain shuffling of glucoamylase genes GAA1 from Aspergillus niger Ld418AI and GATE from Talaromyces emersonii Ld418 TE using overlap extension PCR and were expressed in Saccharomyces cerevisiae W303-1B; only activities of GA1 and GA2 in the fermentation broth were higher than those of GAA1 but less than those of GATE. Further research results of GA1 and GA2 indicated that chimeric glucoamylases GA1 and GA2 revealed increased thermostability compared with GAA1 and GATE, although with a slight change in the activity and optimal temperature. However, GA1 had almost the same catalytic efficiency as GATE, whereas the catalytic efficiency of GA2 was slightly less than that of GATE, but still higher than that of GAA1. The structural analysis showed that the change of enzymatic properties could be caused by the increased and extended α-helix and β-sheet, which change the secondary and tertiary structures of chimeric glucoamylases. These results demonstrated that domain shuffling was feasible to generate a chimeric enzyme with novel properties.