Production of cold-adapted amylase by marine bacterium Wangia sp. C52: optimization, modeling, and partial characterization

Carbohydrate-Binding Module and Linker Allow Cold Adaptation and Salt Tolerance of Maltopentaose-Forming Amylase From Marine Bacterium Saccharophagus degradans 2-40 T

Marine extremophiles produce cold-adapted and/or salt-tolerant enzymes to survive in harsh conditions. These enzymes are naturally evolved with unique structural features that confer a high level of flexibility, solubility and substrate-binding ability compared to mesophilic and thermostable homologs. Here, we identified and characterized an amylase, SdG5A, from the marine bacterium Saccharophagus degradans 2-40 T . We expressed the protein in Bacillus subtilis and found that the purified SdG5A enabled highly specific production of maltopentaose, an important health-promoting food and nutrition component. Notably, SdG5A exhibited outstanding cold adaptation and salt tolerance, retaining approximately 30 and 70% of its maximum activity at 4°C and in 3 M NaCl, respectively. It converted 68 and 83% of starch into maltooligosaccharides at 4 and 25°C, respectively, within 24 h, with 79% of the yield being the maltopentaose. By analyzing the structure of SdG5A, we found that the C-terminal carbohydrate-binding module (CBM) coupled with an extended linker, displayed a relatively high negative charge density and superior conformational flexibility compared to the whole protein and the catalytic domain. Consistent with our bioinformatics analysis, truncation of the linker-CBM region resulted in a significant loss in activities at low temperature and high salt concentration. This highlights the linker-CBM acting as the critical component for the protein to carry out its activity in biologically unfavorable condition. Together, our study indicated that these unique properties of SdG5A have great potential for both basic research and industrial applications in food, biology, and medical and pharmaceutical fields.

Properties and Applications of Extremozymes from Deep-Sea Extremophilic Microorganisms: A Mini Review

The deep sea, which is defined as sea water below a depth of 1000 m, is one of the largest biomes on the Earth, and is recognised as an extreme environment due to its range of challenging physical parameters, such as pressure, salinity, temperature, chemicals and metals (such as hydrogen sulphide, copper and arsenic). For surviving in such extreme conditions, deep-sea extremophilic microorganisms employ a variety of adaptive strategies, such as the production of extremozymes, which exhibit outstanding thermal or cold adaptability, salt tolerance and/or pressure tolerance. Owing to their great stability, deep-sea extremozymes have numerous potential applications in a wide range of industries, such as the agricultural, food, chemical, pharmaceutical and biotechnological sectors. This enormous economic potential combined with recent advances in sampling and molecular and omics technologies has led to the emergence of research regarding deep-sea extremozymes and their primary applications in recent decades. In the present review, we introduced recent advances in research regarding deep-sea extremophiles and the enzymes they produce and discussed their potential industrial applications, with special emphasis on thermophilic, psychrophilic, halophilic and piezophilic enzymes.

Isolation and characterization of a cold-active, alkaline, detergent stable α-amylase from a novel bacterium Bacillus subtilis N8

A cold-active alkaline amylase producer Bacillus subtilis N8 was isolated from soil samples. Amylase synthesis optimally occurred at 15°C and pH 10.0 on agar plates containing starch. The molecular weight of the enzyme was found to be 205 kDa by performing SDS-PAGE. While the enzyme exhibited the highest activity at 25°C and pH 8.0, it was highly stable in alkaline media (pH 8.0-12.0) and retained 96% of its original activity at low temperatures (10-40°C) for 24 hr. While the amylase activity increased in the presence of β-mercaptoethanol (103%); Ba²⁺, Ca²⁺, Na⁺, Zn²⁺, Mn²⁺, H₂O₂, and Triton X-100 slightly inhibited the activity. The enzyme showed resistance to some denaturants: such as SDS, EDTA, and urea (52, 65, and 42%, respectively). N8 α-amylase displayed the maximum remaining activity of 56% with 3% NaCl. The major final products of starch were glucose, maltose, and maltose-derived oligosaccharides. This novel cold-active α-amylase has the potential to be used in the industries of detergent and food, bioremediation process and production of prebiotics.

Extremozymes from Marine Actinobacteria

Marine microorganisms that have the possibility to survive in diverse conditions such as extreme temperature, pH, pressure, and salinity are known as extremophiles. They produce biocatalysts so named as extremozymes that are active and stable at extreme conditions. These enzymes have numerous industrial applications due to its distinct properties. Till now, only a fraction of microorganisms on Earth have been exploited for screening of extremozymes. Novel techniques used for the cultivation and production of extremophiles, as well as cloning and overexpression of their genes in various expression systems, will pave the way to use these enzymes for chemical, food, pharmaceutical, and other industrial applications.

A novel cold-active and salt-tolerant α-amylase from marine bacterium Zunongwangia profunda: molecular cloning, heterologous expression and biochemical characterization

A novel gene (amyZ) encoding a cold-active and salt-tolerant α-amylase (AmyZ) was cloned from marine bacterium Zunongwangia profunda (MCCC 1A01486) and the protein was expressed in Escherichia coli. The gene has a length of 1785 bp and encodes an α-amylase of 594 amino acids with an estimated molecular mass of 66 kDa by SDS-PAGE. The enzyme belongs to glycoside hydrolase family 13 and shows the highest identity (25%) to the characterized α-amylase TVA II from thermoactinomyces vulgaris R-47. The recombinant α-amylase showed the maximum activity at 35 °C and pH 7.0, and retained about 39% activity at 0 °C. AmyZ displayed extreme salt tolerance, with the highest activity at 1.5 M NaCl and 93% activity even at 4 M NaCl. The catalytic efficiency (k cat/K m) of AmyZ increased from 115.51 (with 0 M NaCl) to 143.30 ml mg(-1) s(-1) (with 1.5 M NaCl) at 35 °C and pH 7.0, using soluble starch as substrate. Besides, the thermostability of the enzyme was significantly improved in the presence of 1.5 M NaCl or 1 mM CaCl2. AmyZ is one of the very few α-amylases that tolerate both high salinity and low temperatures, making it a potential candidate for research in basic and applied biology.

Optimization of cold-adapted lysozyme production from the psychrophilic yeast Debaryomyces hansenii using statistical experimental methods

Statistical experimental designs were employed to optimize culture conditions for cold-adapted lysozyme production of a psychrophilic yeast Debaryomyces hansenii. In the first step of optimization using Plackett-Burman design (PBD), peptone, glucose, temperature, and NaCl were identified as significant variables that affected lysozyme production, the formula was further optimized using a four factor central composite design (CCD) to understand their interaction and to determine their optimal levels. A quadratic model was developed and validated. Compared to the initial level (18.8 U/mL), the maximum lysozyme production (65.8 U/mL) observed was approximately increased by 3.5-fold under the optimized conditions.

PRACTICAL APPLICATION

Cold-adapted lysozymes production was first optimized using statistical experimental methods. A 3.5-fold enhancement of microbial lysozyme was gained after optimization. Such an improved production will facilitate the application of microbial lysozyme. Thus, D. hansenii lysozyme may be a good and new resource for the industrial production of cold-adapted lysozymes.