Characterization of Thermostable Serine Alkaline Protease from an Alkaliphilic Strain Bacillus pumilus MCAS8 and Its Applications

Sustainable leather tanning: Enhanced properties and pollution reduction through crude protease enzyme treatment

In this study, proteolytic bacteria, particularly Pseudomonas aeruginosa strain SM4 (OQ349573), were isolated from tannery solid waste dumping yard soil and employed to produce extracellular protease enzymes. The bacteria exhibited optimal growth after 30 h of incubation at 37 °C and pH 7. Under conditions of 55 °C, pH 8, and a substrate concentration of 2 %, the crude enzyme displayed its highest activity at 105 UmL-1. Notably, the produced crude enzyme showed no discernible inhibitory effects on detergents, metal salts, or organic solvents. Application of the crude protease at concentrations of 3 % and 2 % in chrome tanning of goatskins (GS) and cowhides (CH), respectively, yielded significant reductions of 35 % and 30 % in chromium and other post-tanning chemicals compared to conventional processes. Despite the 30 to 35 % reduction in tanning and post-tanning chemicals, the uptake of chrome and associated chemicals by crust leather was higher than observed in conventional processes. Chromium content analysis of the effluent revealed an 81 % reduction during piloting in real industrial operations, accompanied by reductions of about 46 % in BOD and COD pollution loads. The finished leather obtained from the enzymatic process exhibited superior mechanical properties, including higher tensile strengths (210 and 195 kg cm-2), stitch tear (92 and 165 kg cm-1), grain crack load (28 and 32 kg), and distension (73 and 62 mm) for GS and CH, respectively, surpassing or closely aligning with standard values and those obtained in conventional processes.

Molecular Cloning, Characterization, and Application of Organic Solvent-Stable and Detergent-Compatible Thermostable Alkaline Protease from Geobacillus thermoglucosidasius SKF4

Several thermostable proteases have been identified, yet only a handful have undergone the processes of cloning, comprehensive characterization, and full exploitation in various industrial applications. Our primary aim in this study was to clone a thermostable alkaline protease from a thermophilic bacterium and assess its potential for use in various industries. The research involved the amplification of the SpSKF4 protease gene, a thermostable alkaline serine protease obtained from the Geobacillus thermoglucosidasius SKF4 bacterium through polymerase chain reaction (PCR). The purified recombinant SpSKF4 protease was characterized, followed by evaluation of its possible industrial applications. The analysis of the gene sequence revealed an open reading frame (ORF) consisting of 1,206 bp, coding for a protein containing 401 amino acids. The cloned gene was expressed in Escherichia coli. The molecular weight of the enzyme was measured at 28 kDa using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). The partially purified enzyme has its highest activity at a pH of 10 and a temperature of 80°C. In addition, the enzyme showed a half-life of 15 h at 80°C, and there was a 60% increase in its activity at 10 mM Ca2+ concentration. The activity of the protease was completely inhibited (100%) by phenylmethylsulfonyl fluoride (PMSF); however, the addition of sodium dodecyl sulfate (SDS) resulted in a 20% increase in activity. The enzyme was also stable in various organic solvents and in certain commercial detergents. Furthermore, the enzyme exhibited strong potential for industrial use, particularly as a detergent additive and for facilitating the recovery of silver from X-ray film.

Alkaline Thermo- and Oxidant-Stable Protease from Bacillus pumilus Strain TNP93: Laundry Detergent Formulations

The study aims to produce a detergent-compatible and alkaline thermophilic protease from a Bacillus strain and to investigate its usability as a detergent bio-additive. The protease-producing bacterium was identified as Bacillus pumilus strain TNP93 according to the 16S rRNA sequence. The bacterium optimally synthesized the protease at 40 °C and pH 10 in 40 h. The raw protease displayed its optimum activity at pH 10 and 60 °C and its stability between pH 6-13 and 30-100 °C for 24 h. The molecular mass of the proteolytic band was estimated to be about 85 kDa. The protease was not inhibited by any of the metal ions used (Ba2+, Ca2+, Co2+, Cu2+, Mg2+, Mn2+, Zn2+). 97 and 90% of its original activity with 5 mM PMSF and EDTA remained. The activity was measured as 84, 124, and 95%, respectively, in the presence of 1% concentrations of Tween 20, Tween 80, and Triton X-100. In addition, all of its activity was preserved when the enzyme was exposed to 5% H2O2. The end products of casein were detected as tyrosine, aspartic acid, glycine, and cysteine by thin-layer chromatography. Considering the wash performance analysis, the mix of 1% commercial detergent and enzyme almost removed all of the protein-based stains (blood and egg yolk albumin). These remarkable findings indicate that the alkaline, thermo-, and oxidant-stable TNP93 protease is a valuable candidate for usage as a biological additive in various laundry detergents.

Biodegradation and valorization of feather waste using the keratinase-producing bacteria and their application in environmentally hazardous industrial processes

Poultry feathers are widely discarded as waste worldwide and are considered an environmental pollutant and a reservoir of pathogenic bacteria. Therefore, developing sustainable and environmentally friendly methods for managing feather waste is one of the important environmental protection requirements. In this study, we investigated a rapid and eco-friendly method for the degradation and valorization of feather waste using keratinase-producing Pseudomonas geniculata H10, and evaluated the applicability of keratinase in environmentally hazardous chemical processes. Strain H10 completely degraded chicken feathers within 48 h by producing keratinase using them as sources of carbon, nitrogen, and sulfur. The culture contained a total of 402.8 μM amino acids, including 8 essential amino acids, which was higher than the chemical treatment. Keratinase was a serine-type metalloprotease with optimal temperature and pH of 30 °C and 9, respectively, and showed relatively high stability at 10-40 °C and pH 3-10. Keratinase was also able to degrade various insoluble keratins such as duck feathers, wool, human hair, and nails. Furthermore, keratinase exhibited more efficient depilation and wool modification than chemical treatment, as well as novel functionalities such as nematicidal and exfoliating activities. This suggests that strain H10 is a promising candidate for the efficient degradation and valorization of feather waste, as well as the improvement of current industrial processes that use hazardous chemicals.

Isolation and Purification of Bacillus amyloliquefaciens D1 Protease and Its Application in the Fermentation of Soybean Milk to Produce Large Amounts of Free Amino Acids

In this study, a strain of Bacillus amyloliquefaciens D1, with a notably high production of neutral protease, was isolated from Morchella crassipes. The protease was purified to 10.4-fold with a specific activity of 4542.9 U/mg and 2.7% recovery. The enzyme was purified by 70% (NH₄)₂SO₄ and DEAE-Cellulose-52 column. The estimated molecular mass of the purified protease obtained by SDS-PAGE was approximately 40 kDa. The enzyme was optimally active at pH 6.0 and 50 °C. Furthermore, the maximum hydrolysis rate (Vmax) and apparent Michaelis-Menten constant (Km) values of the purified protease were 8.2 mg/mL and 65.7 µg/(min mL). The enzymatic properties and rapid and efficient purification of Bacillus amyloliquefaciens D1 provide the basis for its potential commercialization and industrial development. Moreover, more essential amino acids, such as isoleucine, leucine, and phenylalanine, would be released when the strain fermented soybean milk, and then a better amino acid profile would be formed in soybean milk. Results suggest that this strain exhibits great potential in fermented soybean milk, and the enzyme could lay a foundation for its industrial application and further research.

Formation of recombinant bifunctional fusion protein: A newer approach to combine the activities of two enzymes in a single protein

The tissue of insects, pests, and fungi has a chitin layer followed by protein in the cell membrane. The complete biodegradation of chitin and protein-present in the waste requires the action of two enzymes, namely chitinase, and protease. Combining chitinase and protease in a single protein/enzyme will serve as a bifunctional enzyme that can efficiently degrade the chitin and protein-rich biomass. The present study was aimed to fuse these two enzymes to produce a single protein and study the kinetics of the recombinant fusion protein. A chitinase and alkaline protease genes were isolated, cloned, and expressed successfully as a fusion product in heterologous host Escherichia coli. The two native genes were successfully fused in E.coli by using flexible glycine–serine (G₄S)₂ linker (GGGGS, GS linker). The recombinant fusion protein in E.coli showed hydrolyzed chitin and protein on chitin and bovine serum albumin agar plates confirming the successful cloning and expression of chitinase and protease enzymes in a single fusion protein. The common pUC18-T7 mini vector with the ompA signal sequence helps the extracellular expression of fusion protein efficiently. The native gel electrophoresis revealed a molecular mass of purified protein as 92.0 kDa. The fusion protein’s maximal chitinase and protease activity occurred at pH 5.0 and 8.0 and 30 ⁰C, respectively resembling the individual enzymes’. In the kinetic studies of the fusion protein, it was observed that the presence of metal ions such as Cu²⁺, Na²⁺, and Ca²⁺; significantly enhanced the enzyme activities while organic solvents oxidants and chemicals have drastically affected the activities of both the enzymes in the fusion protein. No such fusion protein has been produced in a heterologous host yet. The reports on fusion protein with biomass-degrading capacity are also scarce. This is probably the first report of a bifunctional chitinase/protease expressed in E. coli.

Isolation and characterization of a new cold-active protease from psychrotrophic bacteria of Western Himalayan glacial soil

As an approach to the exploration of cold-active enzymes, in this study, we isolated a cold-active protease produced by psychrotrophic bacteria from glacial soils of Thajwas Glacier, Himalayas. The isolated strain BO1, identified as Bacillus pumilus, grew well within a temperature range of 4-30 °C. After its qualitative and quantitative screening, the cold-active protease (Apr-BO1) was purified. The Apr-BO1 had a molecular mass of 38 kDa and showed maximum (37.02 U/mg) specific activity at 20 °C, with casein as substrate. It was stable and active between the temperature range of 5-35 °C and pH 6.0-12.0, with an optimum temperature of 20 °C at pH 9.0. The Apr-BO1 had low K_m value of 1.0 mg/ml and V_max 10.0 µmol/ml/min. Moreover, it displayed better tolerance to organic solvents, surfactants, metal ions and reducing agents than most alkaline proteases. The results exhibited that it effectively removed the stains even in a cold wash and could be considered a decent detergent additive. Furthermore, through protein modelling, the structure of this protease was generated from template, subtilisin E of Bacillus subtilis (PDB ID: 3WHI), and different methods checked its quality. For the first time, this study reported the protein sequence for psychrotrophic Apr-BO1 and brought forth its novelty among other cold-active proteases.

Virgibacillus halodenitrificans ST-1 for fermentation of shrimp paste and hydrolysates of its protease

The nutrition and flavor of shrimp paste came from hydrolyzation by enzymes that were produced by microorganisms. The salt-tolerant strain Virgibacillus halodenitrificans ST-1 isolated from shrimp paste was studied and used in the fermentation of shrimp paste. The strain and the protease produced by ST-1 were investigated. The optimum pH of the protease was 8.0, and the reaction temperature was 30°C. The protease showed high activity in the range of pH (5.0-11.0) and NaCl concentration (1%-15%). Divalent cations such as Ba2+, Ca2+, Mg2+, Mn2+, and Si2+ could enhance the protease activity. Residual activity of protease was more than 90% when it was incubated with PMSF and H2O2. Also, the enzyme retained more than 90% of initial activity after it was incubated with organic solvents. Variety of natural proteins could be substrates of the protease. By analyzing the release rate of free amino acids, it was predicted that the cleavage sites of the protease were mainly Glu, Asp, Gly, Leu, and Lys. Moreover, the hydrolysates of the protease had antioxidant activity, especially for DPPH and superoxide anion radical scavenging. The strain ST-1 and the protease both were excellent candidates for food industries.

Enhanced catalytic activity of Bacillus aryabhattai P1 protease by modulation with nanoactivator

In the developing area of modern nanobiotechnology, the research is being focused on enhancement of catalytic performance in terms of efficiency and stability of enzymes to fulfill the industrial demand. In the context of this interdisciplinary era, we isolated and identified alkaline protease producer Bacillus aryabhattai P1 by polyphasic approach and then followed one variable at a time approach to optimize protease production from P1. The modified components of fermentation medium (g/L) were wheat bran 10, soybean flour 10, yeast extract 5, NaCl 10, KH₂PO₄ 1, K₂HPO₄ 1 and MgSO₄·7H₂O 0.2 (pH 9). The optimum alkaline protease production from P1 was recorded 75 ± 3 U/mg at 35 °C and pH 9 after 96 h of fermentation period. Molecular weight of partially purified P1 alkaline protease was 26 KDa as revealed by SDS-PAGE. Calcium based nanoceramic material was prepared by wet chemical precipitation method and doped in native P1 protease for catalytic activity enhancement. Catalytic activity of modified P1 protease was attained by nanoactivator mediated modulation was more by 5.58 fold at pH 10 and 30 °C temperature. The nanoceramic material named as nanoactivator, with grain size of 40–60 nm was suitable to redesign the active site of P1 protease. Such types of modified proteases can be used in different nanobiotechnological applications.

Purification and characterization of a propanol-tolerant neutral protease from Bacillus sp. ZG20

A propanol-tolerant neutral protease was purified and characterized from Bacillus sp. ZG20 in this study. This protease was purified to homogeneity with a specific activity of 26,655 U/mg. The recovery rate and purification fold of the protease were 13.7% and 31.5, respectively. The SDS-PAGE results showed that the molecular weight of the protease was about 29 kDa. The optimal temperature and pH of the protease were 45 °C and 7.0, respectively. The protease exhibited a good thermal- and pH stability, and was tolerant to 50% propanol. Mg²⁺, Zn²⁺, K⁺, Na⁺ and Tween-80 could improve its activity. The calculated K_m and V_max values of the protease towards α-casein were 12.74 mg/mL and 28.57 µg/(min mL), respectively. This study lays a good foundation for the future use of the neutral protease from Bacillus sp. ZG20.

Production and characterization of collagenase from a new Amazonian Bacillus cereus strain

A new collagenase producing a strain of Bacillus cereus, isolated from the pollen of a bee of Amazon Region (Brazil), had its enzyme characterized and the production medium composition and culture conditions enhanced. A two-level design on three factors, namely initial medium pH, the substrate (gelatin) concentration and agitation intensity, allowed identifying the first two variables as the most significant ones, while a central composite design (CCD) was subsequently used to identify their optimal levels. Statistics highlighted maximized collagenolytic activity when substrate concentration and initial medium pH were selected at their highest levels (positive effects), whereas agitation intensity at the lowest (negative effect). Triplicate runs performed under predicted optimal conditions (pH 7.8 and 1.7% gelatin concentration) yielded a collagenolytic activity (305.39 ± 5.15 U) 4.6- to 15-fold those obtained with the preliminary design. The enzyme displayed optimum activity at 45 °C and pH 7.2, was stable over wide ranges of pH values and temperatures (7.2-11.0 and 25-50 °C, respectively) and was strongly inhibited by 10 mM phenylmethylsulphonyl fluoride. The zymogram showed two prominent bands at 50 and 76 kDa. These results are a first attempt to elucidate the features of this new collagenase, its production conditions, and possible scale-up.

A novel alkaline protease from alkaliphilic Idiomarina sp. C9-1 with potential application for eco-friendly enzymatic dehairing in the leather industry

Alkaline proteases have a myriad of potential applications in many industrial processes such as detergent, food and feed production, waste management and the leather industry. In this study, we isolated several alkaline protease producing bacteria from soda lake soil samples. A novel serine alkaline protease (AprA) gene from alkaliphilic Idiomarina sp. C9-1 was cloned and expressed in Escherichia coli. The purified AprA and its pre-peptidase C-terminal (PPC) domain-truncated enzyme (AprA-PPC) showed maximum activity at pH 10.5 and 60 °C, and were active and stable in a wide range of pH and temperature. Ca²⁺ significantly improved the thermostability and increased the optimal temperature to 70 °C. Furthermore, both AprA and AprA-PPC showed good tolerance to surfactants and oxidizing and reducing agents. We found that the PPC domain contributed to AprA activity, thermostability and surfactant tolerance. With casein as substrate, AprA and AprA-PPC showed the highest specific activity of 42567.1 U mg⁻¹ and 99511.9 U mg⁻¹, the K_m values of 3.76 mg ml⁻¹ and 3.98 mg ml⁻¹, and the V_max values of 57538.5 U mg⁻¹ and 108722.1 U mg⁻¹, respectively. Secreted expression of AprA-PPC in Bacillus subtilis after 48 h cultivation resulted in yield of 4935.5 U ml⁻¹ with productivity of 102.8 U ml⁻¹ h⁻¹, which is the highest reported in literature to date. Without adding any lime or sodium sulfide, both of which are harmful pollutants, AprA-PPC was effective in dehairing cattle hide and skins of goat, pig and rabbit in 8–12 h without causing significant damage to hairs and grain surface. Our results suggest that AprA-PPC may have great potentials for ecofriendly dehairing of animal skins in the leather industry.

Ultrabright Red-Emitting Photostable Perylene Bisimide Dyes: New Indicators for Ratiometric Sensing of High pH or Carbon Dioxide

New pH-sensitive perylene bisimide indicator dyes were synthesized and used for fabrication of optical sensors. The highly photostable dyes show absorption/emission bands in the red/near-infrared (NIR) region of the electromagnetic spectrum, high molar absorption coefficients (up to 100 000 m-1  cm-1 ), and fluorescence quantum yields close to unity. The absorption and emission spectra show strong bathochromic shifts upon deprotonation of the imidazole nitrogen atom, which makes the dyes promising as ratiometric fluorescent indicators. Physical entrapment of the indicators into a polyurethane hydrogel enables pH determination at alkaline pH values. It is also shown that a plastic carbon dioxide solid-state sensor can be manufactured by immobilization of the pH indicator in a hydrophilic polymer, along with a quaternary ammonium base. The influences of the plasticizer, different lipophilic bases, and humidity on the sensitivity of the sensor material are systematically investigated. The disubstituted perylene, particularly, features two deprotonation equilibria, enabling sensing over a very broad pCO2 range of 0.5 to 1000 hPa.

Purification and biochemical characterization of a novel thermostable serine alkaline protease from Aeribacillus pallidus C10: a potential additive for detergents

An extracellular thermostable alkaline serine protease enzyme from Aeribacillus pallidus C10 (GenBank No: KC333049), was purified 4.85 and 17. 32-fold with a yield of 26.9 and 19.56%, respectively, through DE52 anion exchange and Probond affinity chromatography. The molecular mass of the enzyme was determined through sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), with approximately 38.35 kDa. The enzyme exhibited optimum activity at pH 9 and at temperature 60 °C. It was determined that the enzyme had remained stable at the range of pH 7.0-10.0, and that it had preserved more than 80% of its activity at a broad temperature range (20-80 °C). The enzyme activity was found to retain more than 70% and 55% in the presence of organic solvents and commercial detergents, respectively. In addition, it was observed that the enzyme activity had increased in the presence of 5% SDS. KM and Vmax values were calculated as 0.197 mg/mL and 7.29 μmol.mL-1.min-1, respectively.

Bioprocess optimization for production of thermoalkali-stable protease from Bacillus subtilis K-1 under solid-state fermentation

Cost-effective production of proteases, which are robust enough to function under harsh process conditions, is always sought after due to their wide industrial application spectra. Solid-state production of enzymes using agro-industrial wastes as substrates is an environment-friendly approach, and it has several advantages such as high productivity, cost-effectiveness, being less labor-intensive, and less effluent production, among others. In the current study, different agro-wastes were employed for thermoalkali-stable protease production from Bacillus subtilis K-1 under solid-state fermentation. Agricultural residues such as cotton seed cake supported maximum protease production (728 U ml(-1)), which was followed by gram husk (714 U ml(-1)), mustard cake (680 U ml(-1)), and soybean meal (653 U ml(-1)). Plackett-Burman design of experiment showed that peptone, moisture content, temperature, phosphates, and inoculum size were the significant variables that influenced the protease production. Furthermore, statistical optimization of three variables, namely peptone, moisture content, and incubation temperature, by response surface methodology resulted in 40% enhanced protease production as compared to that under unoptimized conditions (from initial 728 to 1020 U ml(-1)). Thus, solid-state fermentation coupled with design of experiment tools represents a cost-effective strategy for production of industrial enzymes.

An Alkaline Protease from Bacillus pumilus MP 27: Functional Analysis of Its Binding Model toward Its Applications As Detergent Additive

A proteolytic strain of Bacillus pumilus MP 27 was isolated from water samples of Southern ocean produced alkaline protease. Since protease production need expensive ingredients, an economically viable process was developed by using low cost carbon source, wheat straw, supplemented with peptone. This protease was active within temperature ranges 10–70°C at pH 9. This process was optimized by response surface methodology using a Box Bekhman design by Design Expert 7.0 software that increased the protease activity to 776.5 U/ml. Moreover, the enzyme was extremely stable at a broad range of temperature and pH retaining 69% of its activity at 50°C and 70% at pH 11. The enzyme exhibited excellent compatibility with surfactants and commercial detergents, showing 87% stability with triton X-100 and 100% stability with Tide commercial detergent. The results of the wash performance analysis demonstrated considerably good de-staining at 50 and 4°C with low supplementation (109 U/ml). Molecular modeling of the protease revealed the presence of serine proteases, subtilase family and serine active site and further docking supported the association of catalytic site with the various substrates. Certainly, such protease can be considered as a good detergent additive in detergent industry with a possibility to remove the stains effectively even in a cold wash.

Production and biochemical characterization of an alkaline protease from Aspergillus oryzae CH93

In this study, Aspergillus oryzae CH93 was isolated from soil sample and examined using molecular analysis. Following culture of A. oryzae CH93 under optimal enzyme production, a 47.5kDa extracellular protease was purified using ammonium sulfate precipitation and Q-Sepharose chromatography. The optimal pH 8 and temperature of 50°C obtained for the isolated protease. Sodium dodecyl sulfate (SDS), cetyltrimethyl ammonium bromide (CTAB), H₂O₂ decreased activity, while Triton X-100 and phenylmethanesulfonyl fluoride (PMSF) had no inhibitory effect on the enzyme activity; meanwhile, 2-mercaptoethanol and ethylenediaminetetraacetic acid (EDTA) declined the protease activity. Isoamyl alcohol and acetone (30%) enhanced activity whereas 2-propanol, isopropanol and dimethyl sulfoxide (DMSO) (30%) reduced protease activity. The enzyme exhibited a half-life of 100min at its optimum temperature. Among five substrates of bovine serum albumin (BSA), N-acetyl-l-tyrosine ethyl ester monohydrate (ATEE), casein, azocasein and gelatin results showed that casein is the best substrate with V_max of 0.1411±0.004μg/min and K_m of 2.432±0.266μg/ml. In conclusion, the extracted protease from A. oryzae CH93 as a fungal source possessed biochemical features which could be useful in some application usages.

Thermotolerant alkaline protease enzyme from Bacillus licheniformis A10: purification, characterization, effects of surfactants and organic solvents

In this study, the extracellular thermostable alkaline protease out of A10 strain was purified 1.38-fold with 9.44% efficiency through the ammonium sulfate precipitation-dialysis and DE52 anion exchange chromatography methods. The molecular weight of the enzyme in question along with sodium dodecyl sulfate-polyacrylamide gel electrophoresis was determined to be approximately 40.55 kDa, whereas the optimum pH and temperature ratings were identified as 9.0 and 70 °C, respectively. It was seen that the enzyme had remained stable between pH 7.5-10.5 range, protecting more than 90% of its activity in the wake of 1 h incubation at 60-70 °C. It was also observed that the enzyme enhanced its activity in the presence of Mg(2+), Mn(2+), K(+), while Fe(2+), Ni(2+), Zn(2+), Ag(+ )and Co(2+ ) decreased the activity. Ca(2+), however, did not cause any change in the activity. The enzyme was seen to have been totally inhibited by phenylmethylsulfonyl fluoride, therefore, proved to be a serine alkaline protease.

Biotechnological applications of extremophiles, extremozymes and extremolytes

In the last decade, attention to extreme environments has increased because of interests to isolate previously unknown extremophilic microorganisms in pure culture and to profile their metabolites. Microorganisms that live in extreme environments produce extremozymes and extremolytes that have the potential to be valuable resources for the development of a bio-based economy through their application to white, red, and grey biotechnologies. Here, we provide an overview of extremophile ecology, and we review the most recent applications of microbial extremophiles and the extremozymes and extremolytes they produce to biotechnology.

Detergent-, solvent- and salt-compatible thermoactive alkaline serine protease from halotolerant alkaliphilic Bacillus sp. NPST-AK15: purification and characterization

Alkaline protease produced by the halotolerant alkaliphilic Bacillus sp. strain NPST-AK15 was purified to homogeneity by the combination of ammonium sulfate precipitation, anion-exchange and gel permeation chromatography. The purified enzyme was a monomeric protein with an estimated molecular weight of 32 kDa. NPST-AK15 protease was highly active and stable over a wide pH range, with a maximal activity at pH 10.5. The enzyme showed optimum activity at 60 °C and was stable at 30-50 °C for at least 1 h. Thermal stability of the purified protease was substantially improved by CaCl2 (1.1- to 6.6-fold). The K m, V max and k cat values for the enzyme were 2.5 mg ml(-1), 42.5 µM min(-1) mg(-1), and 392.46 × 10(3) min(-1), respectively. NPST-AK15 protease activity was strongly inhibited by PMSF, suggesting that the enzyme is a serine protease. The enzyme was highly stable in NaCl up to 20 % (w/v). Moreover, the purified enzyme was stable in several organic solvents such as diethyl ether, benzene, toluene, and chloroform. In addition, it showed high stability and compatibility with a wide range of surfactants and commercial detergents and was slightly activated by hydrogen peroxide. These features of NPST-AK15 protease make this enzyme a promising candidate for application in the laundry and pharmaceutical industries.

Enzymes produced by halotolerant spore-forming gram-positive bacterial strains isolated from a resting habitat (Restinga de Jurubatiba) in Rio de Janeiro, Brazil: focus on proteases

The screening for hydrolases-producing, halotolerant, and spore-forming gram-positive bacteria from the root, rhizosphere, and non-rhizosphere soil of Blutaparon portulacoides, a plant found in the Restinga de Jurubatiba located at the northern region of Rio de Janeiro State, Brazil, resulted in the isolation of 22 strains. These strains were identified as Halobacillus blutaparonensis (n = 2), Oceanobacillus picturae (n = 5), and Oceanobacillus iheyensis (n = 15), and all showed the ability to produce different extracellular enzymes. A total of 20 isolates (90.9 %) showed activity for protease, 5 (22.7 %) for phytase, 3 (13.6 %) for cellulase, and 2 (9.1 %) for amylase. Some bacterial strains were capable of producing three (13.6 %) or two (9.1 %) distinct hydrolytic enzymes. However, no bacterial strain with ability to produce esterase and DNase was observed. The isolate designated M9, belonging to the species H. blutaparonensis, was the best producer of protease and also yielded amylase and phytase. This strain was chosen for further studies regarding its protease activity. The M9 strain produced similar amounts of protease when grown either without or with different NaCl concentrations (from 0.5 to 10 %). A simple inspection of the cell-free culture supernatant by gelatin-sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) revealed the presence of three major alkaline proteases of 40, 50, and 70 kDa, which were fully inhibited by phenylmethylsulfonyl fluoride (PMSF) and tosyl-L-phenylalanine chloromethyl ketone (TPCK) (two classical serine protease inhibitors). The secreted proteases were detected in a wide range of temperature (from 4 to 45 °C) and their hydrolytic activities were stimulated by NaCl (up to 10 %). The serine proteases produced by the M9 strain cleaved gelatin, casein, albumin, and hemoglobin, however, in different extensions. Collectively, these results suggest the potential use of the M9 strain in biotechnological and/or industrial processes.

Protease characteristics of bacteriocin producing Lysinibacilli, isolated from fruits and vegetable waste

This study describes the physical stability and optimization of nutrient components for an extracellular protease produced by Bacillus strains isolated from fruits and vegetable waste, Lucknow, India. The isolated proteases could hydrolyze various native proteinaceous substrates such as bovine serum albumin, casein, skim milk, but not the gelatin. The strain JX416854 and isolate 10 yielded maximum protease (831; 703 U/ml) under optimized conditions: Nutrient, Casein broth; pH 7.0; shaking condition 37°C for 36 h. Crude protease exhibited activity over a wide range of pH (6.0-10.0) and found to be stable at (10-70°C), pH stable at 7- 9.0. The significant protease activity was observed with divalent cations Ca2+ and Mg2+ and EDTA. Further, significant blood destaining properties and stabilities with detergents were also observed. Thus, the significant potency and stability of these enzymes indicated their industrial importance and could be an alternative protease for various industrial applications.