Bacillus licheniformis α-amylase: Structural feature in a biomimetic solution and structural changes in extrinsic conditions

Recent advances in the synthesis and medicinal perspective of pyrazole-based α-amylase inhibitors as antidiabetic agents

Diabetes is a serious health threat across the globe, claiming millions of lives worldwide. Among the various strategies employed, inhibition of α-amylase is a therapeutic protocol for the management of Type 2 diabetes mellitus. α-Amylase is a crucial enzyme involved in the breakdown of dietary starch into simpler units. However, the clinically used α-amylase inhibitors have various drawbacks. Therefore, design and development of novel α-amylase inhibitors have gained significant attention. The pyrazole motif has been identified as a versatile scaffold in medicinal chemistry, and recent studies have led to the identification of various pyrazole-based α-amylase inhibitors. This review compiles therapeutic implications of pyrazole-appended α-amylase inhibitors; their synthesis, biological activities, structure-activity relationships and molecular docking studies are discussed.

Exploring microbial diversity in hot springs of Surajkund, India through 16S rRNA analysis and thermozyme characterization from endogenous isolates

Hot springs are a valuable source of biologically significant chemicals due to their high microbial diversity. To investigate the possibilities for industrial uses of these bacteria, researchers collected water and sediment samples from variety of hot springs. Our investigation employed both culture-dependent and culture-independent techniques, including 16S-based marker gene analysis of the microbiota from the hot springs of Surajkund, Jharkhand. In addition, we cultivated thermophilic isolates and screened for their ability to produce amylase, xylanase, and cellulase. After the optimized production of amylase the enzyme was partially purified and characterized using UPLC, DLS-ZP, and TGA. The retention time for the amylase was observed to be around 0.5 min. We confirmed the stability of the amylase at higher temperatures through observation of a steady thermo gravimetric profile at 400 °C. One of the thermophilic isolates obtained from the kund, demonstrated the potential to degrade lignocellulosic agricultural waste.

Hunt for α-amylase from metagenome and strategies to improve its thermostability: a systematic review

With the advent of green chemistry, the use of enzymes in industrial processes serves as an alternative to the conventional chemical catalysts. A high demand for sustainable processes for catalysis has brought a significant attention to hunt for novel enzymes. Among various hydrolases, the α-amylase has a gamut of biotechnological applications owing to its pivotal role in starch-hydrolysis. Industrial demand requires enzymes with thermostability and to ameliorate this crucial property, various methods such as protein engineering, directed evolution and enzyme immobilisation strategies are devised. Besides the traditional culture-dependent approach, metagenome from uncultured bacteria serves as a bountiful resource for novel genes/biocatalysts. Exploring the extreme-niches metagenome, advancements in protein engineering and biotechnology tools encourage the mining of novel α-amylase and its stable variants to tap its robust biotechnological and industrial potential. This review outlines α-amylase and its genetics, its catalytic domain architecture and mechanism of action, and various molecular methods to ameliorate its production. It aims to impart understanding on mechanisms involved in thermostability of α-amylase, cover strategies to screen novel genes from futile habitats and some molecular methods to ameliorate its properties.

Growth-coupled evolution and high-throughput screening assisted rapid enhancement for amylase-producing Bacillus licheniformis

Bacillus licheniformis α-amylase is a thermostable enzyme used in industrial starch hydrolysis. However, difficulties in the genetic manipulation of B. licheniformis hamper further enhancement of α-amylase production. In this regard, adaptive evolution is a useful strategy for promoting the productivity of microbial hosts, although the success of this approach requires the application of suitable evolutionary stress. In this study, we designed a growth-coupled adaptive evolution model to enrich B. licheniformis strains with enhanced amylase productivity and utilization capacity of starch substrates. Single cells of high α-amylase-producing B. licheniformis were isolated using a droplet-based microfluidic platform. Clones with 67% higher α-amylase yield were obtained and analyzed by genome resequencing. Our findings confirmed that growth-coupled evolution combined with high-throughput screening is an efficient strategy for enhanced α-amylase production. In addition, we identified several potential target genes to guide further modification of the B. licheniformis host for efficient protein expression.

Characterization of a salt-resistant fibrinolytic protease of Bacillus licheniformis HJ4 isolated from Hwangseokae jeotgal, a traditional Korean fermented seafood

Bacillus licheniformis HJ4 showing strong fibrinolytic activity was isolated from Hwangseokae jeotgal. aprEHJ4, a major fibrinolytic gene, was cloned by PCR, and an ORF consisting of 379 amino acids was located. The mature enzyme was expected to be 27 kDa in size after processing, but a 24-kDa protein was observed by SDS-PAGE and fibrin zymography, indicating additional processing. RT-qPCR showed that expression level of aprEHJ4 in culture with 0% salt (control) was the highest followed by culture with 8% salt (89.7% of control) and 5% salt (74.2%) at 84 h. The expression level in culture with 15% salt was 46.9%. The results matched with the fibrinolytic activity measurements of cultures and indicated that AprEHJ4 maintained significant activity in the presence of salt up to 15% (w/v). AprEHJ4 was overproduced in Escherichia coli, and mature 27 kDa protein was purified after in vitro renaturation. The optimum pH and temperature of AprEHJ4 were pH 8 and 40 ℃, respectively.

Biochemical and synergistic properties of a novel alpha-amylase from Chinese nong-flavor Daqu

Background

Daqu is the most important fermentation starter for Chinese liquor, with large number of microbes and enzymes being openly enriched in the Daqu system over thousands of years. However, only a few enzymes have been analyzed with crude protein for total liquefying power and saccharifying power of Daqu. Therefore, the complex enzymatic system present in Daqu has not been completely characterized. Moreover, their pivotal and complicated functions in Daqu are completely unknown.

Results

In this study, a novel α-amylase NFAmy13B, from GH13_5 subfamily (according to the Carbohydrate-Active enZYmes Database, CAZy) was successfully heterologous expressed by Escherichia coli from Chinese Nong-flavor (NF) Daqu. It exhibited high stability ranging from pH 5.5 to 12.5, and higher specific activity, compared to other GH13_5 fungal α-amylases. Moreover, NFAmy13B did not show activity loss and retained 96% residual activity after pre-incubation at pH 11 for 21 h and pH 12 for 10 h, respectively. Additionally, 1.25 mM Ca²⁺ significantly improved its thermostability. NFAmy13B showed a synergistic effect on degrading wheat starch with NFAmy13A (GH13_1), another α-amylase from Daqu. Both enzymes could cleave maltotetraose and maltopentaose in same degradation pattern, and only NFAmy13A could efficiently degrade maltotriose. Moreover, NFAmy13B showed higher catalytic efficiency on long-chain starch, while NFAmy13A had higher catalytic efficiency on short-chain maltooligosaccharides. Their different catalytic efficiencies on starch and maltooligosaccharides may be caused by their discrepant substrate-binding region.

Conclusions

This study mined a novel GH13_5 fungal α-amylase (NFAmy13B) with outstanding alkali resistance from Nong-flavor (NF) Daqu. Furthermore, its synergistic effect with NFAmy13A (GH13_1) on hydrolyzing wheat starch was confirmed, and their possible contribution in NF Daqu was also speculated. Thus, we not only provide a candidate α-amylase for industry, but also a useful strategy for further studying the interactions in the complex enzyme system of Daqu.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12934-021-01571-w.

The tale of a versatile enzyme: Alpha-amylase evolution, structure, and potential biotechnological applications for the bioremediation of n-alkanes

As the primary source of a wide range of industrial products, the study of petroleum-derived compounds is of pivotal importance. However, the process of oil extraction and refinement is among the most environmentally hazardous practices, impacting almost all levels of the ecological chain. So far, the most appropriate strategy to overcome such an issue is through bioremediation, which revolves around the employment of different microorganisms to degrade hazardous compounds, generating less environmental impact and lower monetary costs. In this sense, a myriad of organisms and enzymes are considered possible candidates for the bioremediation process. Amidst the potential candidates is α-amylase, an evolutionary conserved starch-degrading enzyme. Notably, α-amylase was not only seen to degrade n-alkanes, a subclass of alkanes considered the most abundant petroleum-derived compounds but also low-density polyethylene, a dangerous pollutant produced from petroleum. Thus, due to its high conservation in both eukaryotic and prokaryotic lineages, in addition to the capability to degrade different types of hazardous compounds, the study of α-amylase becomes a rising interest. Nevertheless, there are no studies that review all biotechnological applications of α-amylase for bioremediation. In this work, we critically review the potential biotechnological applications of α-amylase, focusing on the biodegradation of petroleum-derived compounds. Evolutionary aspects are discussed, as well for all structural information and all features that could impact on the employment of this protein in the biotechnological industry, such as pH, temperature, and medium conditions. New perspectives and critical assessments are conducted regarding the application of α-amylase in the bioremediation of n-alkanes.

Quantitative Structural Analysis of Polystyrene Nanoparticles Using Synchrotron X-Ray Scattering and Dynamic Light Scattering

A series of polystyrene nanoparticles (PS-1, PS-2, PS-3, and PS-4) in aqueous solutions were investigated in terms of morphological structure, size, and size distribution. Synchrotron small-angle X-ray scattering analysis (SAXS) was carried out, providing morphology details, size and size distribution on the particles. PS-1, PS-2, and PS-3 were confirmed to behave two-phase (core and shell) spherical shapes, whereas PS-4 exhibited a single-phase spherical shape. They all revealed very narrow unimodal size distributions. The structural parameter details including radial density profile were determined. In addition, the presence of surfactant molecules and their assemblies were detected for all particle solutions, which could originate from their surfactant-assisted emulsion polymerizations. In addition, dynamic light scattering (DLS) analysis was performed, finding only meaningful hydrodynamic size and intensity-weighted mean size information on the individual PS solutions because of the particles' spherical nature. In contrast, the size distributions were extracted unrealistically too broad, and the volume- and number-weighted mean sizes were too small, therefore inappropriate to describe the particle systems. Furthermore, the DLS analysis could not detect completely the surfactant and their assemblies present in the particle solutions. Overall, the quantitative SAXS analysis confirmed that the individual PS particle systems were successfully prepared with spherical shape in a very narrow unimodal size distribution.

Identification and characterization of a serine protease from Bacillus licheniformis W10: A potential antifungal agent

Bacillus licheniformis W10 is a strain of biocontrol bacteria that was obtained from plant rhizosphere screening. In this study, we purified, identified, and carried out bioinformatics analysis of the W10 antifungal protein from Bacillus licheniformis. Mass spectrometry analysis was carried out by passing the antifungal protein through a high-resolution time-of-flight mass spectrometer. Mascot searches of the tandem mass spectrometry data identified this antifungal protein as a serine protease, and the 1347 bp gene encoding this protein was cloned. Bioinformatics analysis of this protein indicated that it contains 448 amino acid residues, has a molecular weight of 48,794.16 Da and an isoelectric point of 6.04, and is a hydrophilic protein. In the secondary and tertiary structure of this protein, the proportion of α-helices and β-folds is similar, and the protein possesses a Peptidase_S8 conserved domain. Using BApNA as a substrate, it was found that the serine protease inhibitor phenylmethylsulfonyl fluoride (PMSF) can inhibit the W10 antifungal protein. PMSF concurrently reduced the inhibitory effects of the antifungal protein on Botrytis cinerea, showing that the W10 antifungal protein possesses serine protease activity. The W10 antifungal protein has good thermal stability. The study implies potential of this enzyme for biocontrol of fungal plant pathogens.