Purification, biochemical and molecular characterization of a metalloprotease from Pseudomonas aeruginosa MN7 grown on shrimp wastes

Eco-friendly and safe alternatives for the valorization of shrimp farming waste

The seafood industry generates waste, including shells, bones, intestines, and wastewater. The discards are nutrient-rich, containing varying concentrations of carotenoids, proteins, chitin, and other minerals. Thus, it is imperative to subject seafood waste, including shrimp waste (SW), to secondary processing and valorization for demineralization and deproteination to retrieve industrially essential compounds. Although several chemical processes are available for SW processing, most of them are inherently ecotoxic. Bioconversion of SW is cost-effective, ecofriendly, and safe. Microbial fermentation and the action of exogenous enzymes are among the significant SW bioconversion processes that transform seafood waste into valuable products. SW is a potential raw material for agrochemicals, microbial culture media, adsorbents, therapeutics, nutraceuticals, and bio-nanomaterials. This review comprehensively elucidates the valorization approaches of SW, addressing the drawbacks of chemically mediated methods for SW treatments. It is a broad overview of the applications associated with nutrient-rich SW, besides highlighting the role of major shrimp-producing countries in exploring SW to achieve safe, ecofriendly, and efficient bio-products.

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.

Study of nano-hydroxyapatite tagged alkaline protease isolated from Himalayan sub-alpine Forest soil bacteria and role in recalcitrant feather waste degradation

Purified calcium serine metalloprotease from Stenotrophomonas maltophilia strain SMPB12 exhibits highest enzyme activity at pH 9 and temperature range between 15 °C-25 °C. Enzyme supplemented with 40 μM Ca-Hap-NP (NP-protease) showed maximum elevated activity of 17.29 μmole/min/ml (1.9-fold of original protease activity). The thermostability of the enzyme was maintained for 1 h at 60 °C over an alkaline pH range 7.5-10, as compared to the NP untreated enzyme whose activity was of 8.97 μmole/min/ml. A significant loss of activity with EDTA (1.05 μmole/min/ml, 11.75 %), PMSF (0.93 μmole/min/ml, 10.46 %) and Hg2+ (3.81 μmole/min/ml, 42.49 %) was also observed. Kinetics study of NP-protease showed maximum decreases in Km (28.11 %) from 0.28 mM (NP untreated enzyme) to 0.22 mM (NP-protease) along with maximum increase in Vmax (42.88 %) from 1.25 μmole/min/ml to 1.79 μmole/min/ml at varying temperatures. The enhanced activity of NP-protease was able to efficiently degrade recalcitrant solid wastes like feather to produce value-added products like amino acids and helps in declogging recalcitrant solid wastes. The nano-enabled protease may be utilized in a smaller amount for degrading in bulk recalcitrant solid proteinaceous waste at 15 °C temperature as declogging agents providing an eco-friendly efficient process.

Sustainable management of food waste; pre-treatment strategies, techno-economic assessment, bibliometric analysis, and potential utilizations: A systematic review

Food waste (FW) contains many nutritional components such as proteins, lipids, fats, polysaccharides, carbohydrates, and metal ions, which can be reused in some processes to produce value-added products. Furthermore, FW can be converted into biogas, biohydrogen, and biodiesel, and this type of green energy can be used as an alternative to nonrenewable fuel and reduce reliance on fossil fuel sources. It has been demonstrated in many reports that at the laboratory scale production of biochemicals using FW is as good as pure carbon sources. The goal of this paper is to review approaches used globally to promote turning FW into useable products and green energy. In this context, the present review article highlights deeply in a transdisciplinary manner the sources, types, impacts, characteristics, pre-treatment strategies, and potential management of FW into value-added products. We find that FW could be upcycled into different valuable products such as eco-friendly green fuels, organic acids, bioplastics, enzymes, fertilizers, char, and single-cell protein, after the suitable pre-treatment method. The results confirmed the technical feasibility of all the reviewed transformation processes of FW. Furthermore, life cycle and techno-economic assessment studies regarding the socio-economic, environmental, and engineering aspects of FW management are discussed. The reviewed articles showed that energy recovery from FW in various forms is economically feasible.

Expression of a Salt-Tolerant Pseudolysin in Yeast for Efficient Protein Hydrolysis under High-Salt Conditions

Protease biocatalysis in a high-salt environment is very attractive for applications in the detergent industry, the production of diagnostic kits, and traditional food fermentation. However, high-salt conditions can reduce protease activity or even inactivate enzymes. Herein, in order to explore new protease sources, we expressed a salt-tolerant pseudolysin of Pseudomonas aeruginosa SWJSS3 isolated from deep-sea mud in Saccharomyces cerevisiae. After optimizing the concentration of ion cofactors in yeast peptone dextrose (YPD) medium, the proteolytic activity in the supernatant was 2.41 times more than that in the control group when supplemented with 5 mM CaCl₂ and 0.4 mM ZnCl₂. The extracellular proteolytic activity of pseudolysin reached 258.95 U/mL with optimized expression cassettes. In addition, the S. cerevisiae expression system increased the salt tolerance of pseudolysin to sodium chloride (NaCl)and sodium dodecyl sulfate (SDS) and the recombinant pseudolysin retained 15.19% activity when stored in 3 M NaCl for 7 days. The recombinant pseudolysin was able to efficiently degrade the β-conglycinin from low-denatured soy protein isolates and glycinin from high-denatured soy protein isolates under high temperatures (60 °C) and high-salt (3 M NaCl) conditions. Our study provides a salt-tolerant recombinant protease with promising applications in protein hydrolysis under high-salt conditions.

Evaluation of the biotechnological potential of a novel purified protease BS1 from Bacillus safensis S406 on the chitin extraction and detergent formulation

An extracellular alkaline stable protease BS1 from a new bacteria strain, Bacillus safensis S406, isolated from the Sfax solar saltern, was purified and characterized. The enzyme was purified to homogeneity by ammonium sulfate precipitation, Sephadex G-75 gel filtration, Mono-Q anion-exchange chromatography and ultrafiltration, with a 12.70-fold increase in specific activity and 20.29% recovery. The enzyme has a molecular weight of 29kDa and appeared as a single band on native-PAGE. The optimum pH and temperature values of its proteolytic activity were pH 11.0 and 60°C, respectively. BS1 was tested for the deproteinization of shrimp wastes to extract chitin. An enzyme-protein ratio of 10U/mg of proteins allows to eliminate 93% of protein linked to the chitin after 3h hydrolysis at 45°C. Being very active in alkaline conditions, the potential application of BS1 in laundry formulation was investigated. The enzyme showed high stability in the presence of non-ionic surfactants and some commercial liquid and solid detergents, suggesting its eventual use in detergent formulations.

Optimization of protease production from surface-modified coffee pulp waste and corncobs using Bacillus sp. by SSF

The aim of the study was to identify new sources of substrate from agro-industrial waste for protease production using Bacillus sp., a local bacteria isolated from an agro-waste dumping site. The strain was identified as Bacillus sp. BT MASC 3 by 16S rRNA sequence followed by phylogenic analysis. Response surface methodology-based Box-Behnken design (BBD) was used to optimize the variables such as pH, incubation time, coffee pulp waste (CPW) and corncob (CC) substrate concentration. The BBD design showed a reasonable adjustment of the quadratic model with the experimental data. Statistics-based contour and 3-D plots were generated to evaluate the changes in the response surface and understand the relationship between the culture conditions and the enzyme yield. The maximum yield of protease production (920 U/mL) was achieved after 60 h of incubation with 3.0 g/L of CPW and 2.0 g/L of CC at pH 8 and temperature 37 °C in this study. The molecular mass of the purified enzyme was 46 kDa. The highest activity was obtained at 50 °C and pH 9 for the purified enzymes.

Statistical optimization of alkaline protease production from brackish environment Bacillus sp. SKK11 by SSF using horse gram husk

Protease production by Bacillus sp. SKK11 isolated from brackish environment was studied by solid-state fermentation with horse gram husk. Response surface methodology-based Box-Behnken design (BBD) was used to optimize the variables such as pH, maltose, and MgSO₄. The BBD design analysis showed a reasonable adjustment of the quadratic model with the experimental data. Statistics-based contour and three-dimensional (3-D) plots were generated to evaluate the changes in the response surface and to understand the relationship between the enzyme yield and the culture conditions. The maximum yield of the enzyme was observed at pH 9.0.

Solvent-stable digestive alkaline proteinases from striped seabream (Lithognathus mormyrus) viscera: characteristics, application in the deproteinization of shrimp waste, and evaluation in laundry commercial detergents

Alkaline proteases from the viscera of the striped seabream (Lithognathus mormyrus) were extracted and characterized. Interestingly, the crude enzyme was active over a wide range of pH from 6.0 to 11.0, with an optimum pH at the range of 8.0-10.0. In addition, the crude protease was stable over a broad pH range (5.0-12.0). The optimum temperature for enzyme activity was 50 °C. The crude alkaline proteases showed stability towards various surfactants and bleach agents and compatibility with some commercial detergents. It was stable towards several organic solvents and retained more than 50% of its original activity after 30 days of incubation at 30 °C in the presence of 25% (v/v) dimethyl sulfoxide, N,N-dimethylformamide, diethyl ether, and hexane. The crude enzyme extract was also tested for shrimp waste deproteinization in the preparation of chitin. The protein removal with a ratio enzyme/substrate of 10 was about 79%.

Purification of Protease from Pseudomonas thermaerum GW1 Isolated from Poultry Waste Site

An extracellular protease was purified from Pseudomonas thermaerum GW1 a new strain identified by morphological, biochemical and 16S rDNA sequencing. It was isolated from soil of Poultry waste site at Ghazipur near Ghaziabad, Delhi. The strain produces extra cellular protease in the culture media that was maintained at 37°C, 140 rpm. The media was harvested for protease after 48 hrs of incubation at 37°C in basal media supplemented with 1% casein. We report 6.08 fold purification of enzyme following ammonium sulphate precipitation and DEAE-cellulose chromatography. The molecular weight of the enzyme was estimated to be approximately 43,000 daltons as shown by casein zymography studies. The optimum pH for the proteolytic activity was pH 8.0 and enzyme remained stable between pH 5 -11 at 60°C. Interestingly Mn²⁺ (5mM) activated enzyme activity by 5 fold, while Cu²⁺, Mg²⁺and Ca²⁺ moderately activated enzyme activity, where as Zn²⁺, Fe²⁺ and Hg²⁺ inhibited enzyme activity. The protease produced was stable in presence of 50 % (v/v) ethylacetate and acetone. Isopropanol, methanol and benzene increased protease activity by 2.7, 1.3 and 1.1 fold respectively but was inhibited in presence of glycerol and DMSO. This organic solvent-stable protease could be used as a biocatalyst for enzymatic peptide synthesis

Low-cost fermentation medium for alkaline protease production by Bacillus mojavensis A21 using hulled grain of wheat and sardinella peptone

Media composition and culture conditions for surfactant stable alkaline protease production by Bacillus mojavensis A21 were optimized using two statistical methods. Plackett-Burman design was applied to find the optimal ingredients and conditions to improve yields. Response surface methodology (RSM), including central composite design, was used to determine the optimal concentrations and conditions. The results indicated that several components, including hulled grain of wheat (HGW), sardinella peptone (SP), NaCl, CaCl(2), MgSO(4), K(2)HPO(4), KH(2)PO(4), agitation, culture temperature and initial medium pH, had significant effects on production. The statistical model was constructed via central composite design (CCD) using four selected variables (HGW, NaCl, KH(2)PO(4) and K(2)HPO(4)). Under the proposed optimized conditions, the protease experimental yield (1860.63U/mL) closely matched the yield predicted by the statistical model (1838.60U/mL) with R(2)=0.98. An overall 14.0-fold increase in protease production was achieved using the optimized medium (HGW 30.0g/L, SP 1.0g/L, NaCl 2.0g/L, KH(2)PO(4) 1.0g/L, K(2)HPO(4) 0.3g/L, CaCl(2) 2.0g/L, MgSO(4) 1.0g/L and pH 9.0, compared with the unoptimized basal medium (starch 10.0g/L, yeast extract 2.0g/L, KH(2)PO(4) 0.1g/L, K(2)HPO(4) 0.1g/L, CaCl(2) 0.5g/L and pH 8.0; 137U/mL). A successful and significant improvement (14-fold) in the production of protease by the A21 strain was accomplished using cheap carbon and nitrogen substrates (HGW and SP), which may result in a significant reduction in the cost of medium constituents.

An oxidant- and organic solvent-resistant alkaline metalloprotease from Streptomyces olivochromogenes

Organic solvent- and detergent-resistant proteases are important from an industrial viewpoint. However, they have been less frequently reported and only few of them are from actinomycetes. A metalloprotease from Streptomyces olivochromogenes (SOMP) was purified by ion exchange with Poros HQ and gel filtration with Sepharose CL-6B. Apparent molecular mass of the enzyme was estimated to be 51 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and gelatin zymography. The activity was optimum at pH 7.5 and 50 degrees C and stable between pH 7.0 and 10.0. SOMP was stable below 45 degrees C and Ca(2+) increased its thermostability. Ca(2+) enhanced while Co(2+), Cu(2+), Zn(2+), Mn(2+), and Fe(2+) inhibited the activity. Ethylenediaminetetraacetic acid and ethylene glycol-bis (beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid, but not phenylmethylsulfonyl fluoride, aprotinin, and pefabloc SC, significantly suppressed the activity, suggesting that it might be a metalloprotease. Importantly, it is highly resistant against various detergents, organic solvents, and oxidizing agents, and the activity is enhanced by H(2)O(2). The enzyme could be a novel protease based on its origin and peculiar biochemical properties. It may be useful in biotechnological applications especially for organic solvent-based enzymatic synthesis.

Isolation and partial characterization of protease from Pseudomonas aeruginosa ATCC 27853

Enzymatic characteristics of a protease from medically important, referent strain of Pseudomonas aeruginosa ATCC 27853 were determined. According to SDS PAGE and gel filtration it was estimated that molecular mass of the purified enzyme was about 15 kDa. Other enzymatic properties were found to be: pH optimum 7.1, pH stability between pH 6.5 and pH 10; temperature optimum around 60?C while the enzyme was stable at 60?C for 30 min. The inhibition of the enzyme was observed with the metal chelators such as EDTA and 1,10- phenanthroline, suggesting that the protease is a metalloenzyme. Further more it was determined that enzyme contains one mole of zinc ion per mole of enzyme. The protease is stable in the presence of different organic solvents, which enable potential use for synthesis of peptides.

Fibrinolytic enzymes from a newly isolated marine bacteriumBacillus subtilisA26: characterization and statistical media optimization

A fibrinolytic enzyme producing bacterium was isolated and identified as Bacillus subtilis A26 on the basis of the 16S rRNA gene sequence. The fibrin zymography analysis reveals the presence of at least three fibrinolytic enzymes. The crude enzyme exhibited maximal activity at 60 °C and pH 8.0. Medium composition and culture conditions for the enzyme production by B. subtilis A26 were optimized using two statistical methods. The Plackett–Burman statistical design was applied to find the key ingredients and conditions for the best yield of enzyme production. Five significant variables (hulled grain of wheat, casein peptone, NaCl, CaCl2, and initial pH) were selected for the optimization studies. The response surface methodological approach was used to determine the optimal concentrations and conditions. The optimized medium contained 40.0 g·L–1hulled grain of wheat, 3.53 g·L–1casein peptone, 4.0 g·L–1CaCl2, 3.99 g·L–1NaCl, 0.01 g·L–1MgSO4, and 0.01 g·L–1KH2PO4, pH 7.78. The medium optimization resulted in a 4.2-fold increased level of fibrinolytic production (269.36 U·mL–1) compared with that obtained with the initial medium (63.45 U·mL–1). A successful and significant improvement in the production of protease by the A26 strain was accomplished using inexpensive carbon substrate (hulled grain of wheat), allowing a significant reduction in the cost of medium constituents.