Purification and characterization of a novel extracellular alkaline protease from Cellulomonas bogoriensis

Insights into the mechanism of extracellular proteases from Penicillium on myofibrillar protein hydrolysis and volatile compound evolutions

To investigate the mechanism of Penicillium proteases on the hydrolysis of myofibrillar protein (MP) and volatile compound evolutions, enzymatic characteristics of Penicillium proteases, hydrolysis capacities for MP, interactions between Penicillium proteases and MP, and profile changes of volatile compounds were investigated. P. aethiopicum (PA) and P. chrysogenum (PC) proteases showed the largest hydrolysis activities at pH 9.0 and 7.0, and were identified as alkaline serine protease and serine protease by LC-MS/MS, respectively. The proteases of PA and PC significantly degraded myosin and actin, and PA protease showed higher hydrolysis capacity for myosin than that of PC protease, which was confirmed by higher proteolysis index (56.06 %) and lower roughness (3.99 nm) of MP after PA treatment. Molecular docking revealed that hydrogen bond and hydrophobic interaction were the major interaction forces of Penicillium proteases with myosin and actin, and PA protease showed more binding sites with myosin compared with PC protease. The total content of free amino acids increased to 6.02-fold for PA treatment and to 5.51-fold for PC treatment after 4 h hydrolysis of MP, respectively. GC-MS showed that aromatic aldehydes and pyrazines in PA showed the largest increase compared with the control and PC during the hydrolysis of MP. Correlation analysis demonstrated that Phe, Leu and Ile were positively related with the accumulation of benzaldehyde, benzeneacetaldehyde, 2,4-dimethyl benzaldehyde and 2,5-dimethyl pyrazine.

Optimization, partial purification, and characterization of a novel high molecular weight alkaline protease produced by Halobacillus sp. HAL1 using fish wastes as a substrate

BACKGROUND

Hydrolytic enzymes from halophilic microorganisms have a wide range of industrial applications. Herein, we report the isolation of Halobacillus sp. HAL1, a moderately halophilic bacterium that produces a novel high molecular weight extracellular alkaline protease when grown in fish processing wastes as a substrate.

RESULTS

Results showed that the isolated strain belonged to the genus Halobacillus, and it was designated as Halobacillus sp. HAL1 with the GenBank accession number OK001470. The strain secreted an extracellular alkaline protease, and the highest yield was obtained when it was grown in a medium with fish wastes substrate as the sole nutritional source (10 g/L) and incubated at 25 °C under shaking conditions. The enzyme was partially purified by Sephadex G-100 column chromatography. Zymographic analysis showed two casein degrading bands of about 190 and 250 KDa. The optimum enzyme activity was at a temperature of 50 °C at pH 8. The proteolytic activity was enhanced in the presence of metal ions (Ca²⁺, Mg²⁺, and Mn²⁺), surfactants (Tween 80, SDS, and Triton-X100), H₂O₂, and EDTA.

CONCLUSION

Our study indicates that Haobacillus sp. HAL1 is a moderately halophilic strain and secrets a novel high molecular wight alkaline protease that is suitable for detergent formulation.

Optimization of bioprocesses with Brewers’ spent grain and Cellulomonas uda

Brewers’ spent grain (BSG) is a low‐value by‐product of the brewing process, which is produced in large quantities every year. In this study, the lignocellulosic feedstock (solid BSG) was used to optimize fermentations with Cellulomonas uda. Under aerobic conditions, maximum cellulase activities of 0.98 nkat∙mL⁻¹, maximum xylanase activities of 5.00 nkat∙mL⁻¹ and cell yields of 0.22 g_Cells∙g_BSG⁻¹ were achieved. Under anaerobic conditions, enzyme activities and cell yields were lower, but valuable liquid products (organic acids, ethanol) were produced with a yield of 0.41 g_Prod∙g_BSG⁻¹. The growth phase of the organisms was monitored by measuring extracellular concentrations of two fluorophores pyridoxin (aerobic) and tryptophan (anaerobic) and by cell count. By combining reductive with anaerobic conditions, the ratio of ethanol to acetate was increased from 1.08 to 1.59 mol_EtOH∙mol_Ac⁻¹. This ratio was further improved to 9.2 mol_EtOH∙mol_Ac⁻¹ by lowering the pH from 7.4 to 5.0 without decreasing the final ethanol concentration. A fermentation in a bioreactor with 15 w% BSG instead of 5 w% BSG quadrupled the acetate concentration, whilst ethanol was removed by gas stripping. This study provides various ideas for optimizing and monitoring fermentations with solid substrates, which can support feasibility and incorporation into holistic biorefining approaches in the future.

High level expression and biochemical characterization of an alkaline serine protease from Geobacillus stearothermophilus to prepare antihypertensive whey protein hydrolysate

BACKGROUND

Proteases are important for hydrolysis of proteins to generate peptides with many bioactivities. Thus, the development of novel proteases with high activities is meaningful to discover bioactive peptides. Because natural isolation from animal, plant and microbial sources is impractical to produce large quantities of proteases, gene cloning and expression of target protease are preferred.

RESULTS

In this study, an alkaline serine protease gene (GsProS8) from Geobacillus stearothermophilus was successfully cloned and expressed in Bacillus subtilis. The recombinant GsProS8 was produced with high protease activity of 3807 U/mL after high cell density fermentation. GsProS8 was then purified through ammonium sulfate precipitation and a two-step chromatographic method to obtain the homogeneous protease. The molecular mass of GsProS8 was estimated to be 27.2 kDa by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and 28.3 kDa by gel filtration. The optimal activity of GsProS8 was found to be pH 8.5 and 50 °C, respectively. The protease exhibited a broad substrate specificity and different kinetic parameters to casein and whey protein. Furthermore, the hydrolysis of whey protein using GsProS8 resulted in a large amount of peptides with high angiotensin-I-converting enzyme (ACE) inhibitory activity (IC₅₀ of 0.129 mg/mL).

CONCLUSIONS

GsProS8 could be a potential candidate for industrial applications, especially the preparation of antihypertensive peptides.

Two steps purification, biochemical characterization, thermodynamics and structure elucidation of thermostable alkaline serine protease from Nocardiopsis alba strain OM-5

The Nocardiopsis alba strain OM-5 showed maximum protease production in submerged culture. The OM-5 protease was purified by hydrophobic interaction chromatography. The purified protease of 68 kDa showed maximum activity (3312 ± 1.64 U/mL) at 70 °C and was quite stable at 80 °C up to 4 M NaCl (w/v) at pH 9. The purified protease showed significant activity and stability in different cations, denaturing agents, metal ions, and osmolytes. The thermodynamic parameters including deactivation rate constant (K_d) and half lives (t_1/2) at 50-80 °C were in the range of 2.50 × 10^-3 to 5.50 × 10^-3 and 277.25-111.25 min respectively at 0-4 M NaCl. The structural stability of the OM-5 protease under various harsh conditions was elucidated by circular dichroism (CD) spectroscopy followed by K2D3 analysis revealed that the native structure of OM-5 protease was stable even in sodium dodecyl sulfate and Tween 20 indicated by increased α-helices content assisted with decreased β-sheets content.

Characterization and immobilization of protease secreted by the fungus Moorella speciosa

Protease was extracellularly produced in submerged fermentation by the fungus Moorella speciosa with maximum activity of 8.6 × 10³ U/mL. The optimal pH and temperature for enzyme activity were 6.78 and 60.88 °C, respectively. The enzyme was incubated in the presence of several ions at concentrations of 0.1 M and 0.01 M to address the effect on enzyme activity. Enzyme activity was increased by 56% and 130% in the presence of 0.1 M BaCl₂ and of 0.01 M Na₂SO₄, respectively. The V _max and K _m values were 0.01474 U/min/mg protein and 0.04190 mg/mL, respectively. The enzyme retained about 90% of enzymatic activity at 90 °C. Among the methods tested for enzyme immobilization, adsorption onto MAT540 carrier led to the most promising results, since after 15 reuse cycles up to 60% of the initial catalytic activity was retained. Entrapment in calcium alginate matrix allowed to retain up to 51% of the initial catalytic activity after 8 reuse cycles. This protease from M. speciosa, in either free or immobilized form, can be foreseen as a useful biocatalytic tool in process design by reducing operating costs, decreasing the use of chemical processing and, consequently, meeting the global demand for clean technologies.

Recombinant expression and characterization of two glycoside hydrolases from extreme alklinphilic bacterium Cellulomonas bogoriensis 69B4T

Two novel glycoside hydrolases were cloned from the genomic DNA of alklinphilic bacterium Cellulomonas bogoriensis 69B4^T and functionally expressed in Escherichia coli. The two enzymes shared less than 73% of identities with other known glycosidases and belonged to glycoside hydrolase families 5 and 9. Recombinant Cel5A exhibited optimum activity at pH 5.0 and at a temperature of 70 °C, and Cel9A showed optimum activity at pH 7.0 and at a temperature of 60 °C. The two enzymes exhibited activity at alkaline pH 11 and were stable over a wide range of pH. The maximum activities of Cel5A and Cel9A were observed in 0.5 M NaCl and 1 M KCl, respectively. In addition, these two enzymes exhibited excellent halostability with residual activities of more than 70% after pre-incubation for 6 days in 5 M NaCl or 4 M KCl. Substrate specificity analysis revealed that Cel5A and Cel9A specifically cleaved the β-1,4-glycosidic linkage in cellulose with the highest activity on carboxymethyl cellulose sodium (78.3 and 145.3 U/mg, respectively). Cel5A is an endoglucanase, whereas Cel9A exhibits endo and exo activities. As alkali-activated, thermo-tolerant, and salt-tolerant cellulases, Cel5A and Cel9A are promising candidates for further research and industrial applications.

Biochemical, thermodynamic and structural characteristics of a biotechnologically compatible alkaline protease from a haloalkaliphilic, Nocardiopsis dassonvillei OK-18

This report describes purification strategies, biochemical properties and thermodynamic analysis of an alkaline serine protease from a marine actinomycete, Nocardiopsis dassonvillei strain OK-18. The solvent tolerance, broad thermal-pH stability, favourable kinetics and thermodynamics suggest stability of the enzymatic reaction. The enzyme was active in the range of pH 7-12 and 37-90 °C, optimally at pH 9 and 70 °C. The deactivation rate constant (Kd), half-life (t½), enthalpy (ΔH*), entropy (ΔS*), activation energy (E) and change in free energy (ΔG*) suggested stability and spontaneity of the reaction. β-Sheets as revealed by the Circular dichroism (CD) spectroscopy, were the major elements in the secondary structure of the enzyme, while Fourier-transform infrared spectroscopy (FTIR) indicated the presence of amide I and amide II. Based on the liquid chromatography quadrupole time-of-flight mass spectrometry (LC-QToF-MS) analysis, the amino acid sequence had only 38% similarity with other proteases of Nocardiopsis strains, suggesting its novelty. The Ramachandran Plot revealed the location of the amino acid residues in the most favored region. The blood de-staining, gelatin hydrolysis, silver recovery and deproteinization of crab shells established the biotechnological potential of the enzyme.

Alkaline serine protease from the new halotolerant alkaliphilic Salipaludibacillus agaradhaerens strain AK-R: purification and properties

Herein, we report the purification and characterization of an alkaline protease from the alkaliphilic Salipaludibacillus agaradhaerens (formerly Bacillus agaradhaerens) strain AK-R, which was previously isolated from Egyptian soda lakes. The purification procedures resulted in enzyme purification up to 13.3-fold, with a recovery yield of 16.3% and a specific activity of 3488 U/mg protein. AK-R protease was a monomeric protein with an estimated molecular weight of 33.0 kDa. The optimum pH and temperature for AK-R protease were pH 10 and 60 °C, respectively. The enzyme thermostability was significantly enhanced in the presence of CaCl₂ by approximately 1.3-fold. Moreover, under optimal conditions, the K _m and V _max values of the enzyme were 2.63 mg/ml and 4166.7 U/mg, respectively. PMSF caused complete inhibition of the enzyme activity, suggesting that AK-R belongs to the serine protease family. In addition, the enzyme was completely inhibited by EDTA, revealing the requirement of metal ions for AK-R protease activity; hence, it can be classified as a metalloprotease. AK-R protease is a mostly thiol-independent enzyme, since thiol reductants such as β-mercaptoethanol and dithiothreitol had no effect on the enzyme activity. AK-R protease exhibited high stability in several organic solvents, including butanol, amyl alcohol, dimethyl ether, toluene, diethyl ether and methanol. Moreover, AK-R protease showed significant stability to a variety of surfactants and commercial detergents. The features and properties of AK-R alkaline protease are favourable and suggest its potential applications in various industries, particularly in the laundry detergent industry.

A novel thiol-dependent serine protease from Neocosmospora sp. N1

Alkaline proteases have several industrial applications. In the present study, newly isolated Neocosmospora sp. N1 was screened as hyper producer of serine protease. A multimeric protease of the fungus was purified to homogeneity till 96.78 fold purification with 22.51% recovery. The homogeneity of purified enzyme was checked by native PAGE and its molecular weight was found to be 198.03 kDa by MALDI-TOF. On SDS-PAGE analysis, enzyme was found to be a hetero oligomer of 17.66 kDa and 20.89 kDa subunits. The purified enzyme showed maximum activity with casein as substrate at 60 °C and pH 8.5. The K_m and V_max values were found to be 0.015 mg/ml and 454.45 U/ml, respectively. The enzyme was completely inhibited by PMSF, while the activity was 40% enhanced using β-mercaptoethanol, suggesting that it is a thiol-dependent serine protease. The purified protease was active over an alkaline pH range from 7 to 12 and temperatures from 20 °C to 60 °C. The enzyme exhibited excellent stability, almost 100% towards organic solvents such as toluene, benzene and hexane, surfactants such as Triton X-100, Tween-20, Tween-80 and SDS, as well as commercial detergents. The significant properties of purified enzyme assure that it could be a potential candidate for commercial purposes.

Purification and characterization of the thermostable protease produced by Serratia grimesii isolated from channel catfish

BACKGROUND

Microbial spoilage of fishery products accounts for significant financial losses, yearly on a global scale. Psychrotrophic spoilage bacteria often secrete extracellular enzymes to break down surrounding fish tissue, rendering the product unsuitable for human consumption. For a better understanding of bacterial spoilage due to enzymatic digestion of fish products, proteases in Serratia grimesii isolated from North American catfish fillets (Ictalurus punctatus) were investigated.

RESULTS

Mass spectrometric evidence demonstrated that S. grimesii secretes two distinct extracellular proteases and one lipase. Protease secretion displayed broad thermostability in the 30-90 °C range. The major protease-secretion (O-1) was most active under alkaline conditions and utilized manganese as a co-factor. Organic solvents significantly disrupted the efficacy of S. grimesii extracellular enzymes and, in a series of bactericidal detergents, protease activity was highest when treated with Triton X-100. Ethylenediaminetetraacetic acid (EDTA) and phenylmethylsulfonyl fluoride (PMSF) significantly inhibited the enzyme activity, while protease was moderately stable under freeze-thaw and refrigerated storage.

CONCLUSION

The influence of fish spoilage-related enzymes, depending on various factors, is discussed in this paper. This study will provide new insight into enzymatic spoilage and its control, which can be exploited to enhance food safety and the shelf-life of fishery products worldwide. © 2018 Society of Chemical Industry.

Purification and characterization of alkaline soda-bleach stable protease from Bacillus sp. APP-07 isolated from Laundromat soil

The detergent-compatible alkaline protease was produced from the bacterial strain Bacillus sp. APP-07 isolated from Laundromat soil of Solapur, Maharashtra, India. The culture was grown in 1000 ml capacity baffled flask with a working volume of 100 ml and incubated at 55 °C for 33 h on a rotary shaker. After incubation, alkaline protease was partially purified by the sequential method of acetone precipitation followed by nominal molecular weight limit (NMWL) cut-off ultrafiltration using 50 K and 10 K filters. Finally, Sephadex G-100 gel filtration chromatographic purification was performed to obtain 3.12 fold purified alkaline protease enzyme with a 66.67% final yield. The purified enzyme showed 31907.269 units (U) of enzyme activity containing 8741.718 U/mg of specific enzyme activity. The molecular weight of the enzyme was confirmed about 33.0 kDa (kDa) by the SDS-PAGE analysis. The purified enzyme was stable at higher pH and temperature range, with an optimum pH 10.5 and temperature 55 °C. The enzyme showed excellent stability and compatibility in various detergents, surfactants, bleach, and oxidizing agents. The enzyme activity enhanced in the presence of Ca2+, Cu2+, and surfactants, whereas; the phenylmethylsulphonyl fluoride (PMSF) and Diisopropyl fluorophosphate (DFP) completely inhibit the enzymatic activity, which pointed out that the enzyme affiliated to serine-centered metalloproteases family. In conclusion, the remarkable tolerance and stability of the enzyme explored the promising candidature for the several potential applications in the laundry detergents. The sustainability of the enzyme might serve several possible applications in the laundry detergents, leather industries, and other harsh industrial processes.

Expression, purification and characterization of halophilic protease Pph_Pro1 cloned from Pseudoalteromonas phenolica

In this study, protease Pph_Pro1 from Pseudoalteromonas phenolica, possessing extracellular proteolytic activity and salt tolerance, was investigated for cloning, expression, and purification purposes. Through optimization, it was determined that optimum soluble recombinant expression was achieved when Pph_Pro1 was co-expressed with the pTf16 vector chaperone in LB medium supplemented with CaCl₂. Pph_Pro1 was purified using osmotic shock and immobilized metal-affinity chromatography (IMAC). Isolated Pph_Pro1 activity was measured as 0.44 U/mg using casein as a substrate. Interestingly, Pph_Pro1 displayed halophilic, alkaliphilic, and unexpected thermostable properties. Furthermore, it was resistant to several hydrophilic and hydrophobic organic solvents. Substrate specificity and kinetic values such as K_m and V_max were determined with casein, bovine serum albumin (BSA), and algal waste protein as substrates, indicating that the Pph_Pro1 protease enzyme had a greater affinity for casein. Based on the remarkable characteristics of this Pph_Pro1 protease enzyme, it can potentially be utilized in many biotechnological industries.

Enzymatic synthesis of isomaltotriose palmitate and evaluation of its emulsifying property

Enzymatic syntheses of oligosaccharide fatty acid esters are important owing to their wide range of industrial applications in the food, cosmetic, and pharmaceutical industries. Transesterification of isomaltotriose and palmitic acid vinyl ester, catalyzed by the metalloprotease thermolysin, was performed in organic solvents. The process parameters (reaction time and temperature) were optimized to achieve the highest yield of isomaltotriose palmitate (IP). The water content of the reaction system played a key role in the acylation of isomaltotriose. Dimethyl sulfoxide was thought to be the most suitable reaction medium by taking the degree of substitution of the modified isomaltotriose into account. The optimum reaction time, temperature, water content, and enzyme concentration were 24h, 45°C, 40%, and 0.05%, respectively, under which the product yield was as high as 89.7%. The enzyme operational stability study showed that thermolysin retained 51.5% of its initial activity for the synthesis of IP (even after repeated use for 72h). Moreover, test results showed that the emulsifying capacity and emulsion stability of IP are 107.5mL oil/g ester and 16.3%, respectively.