Lime and Sulphide-Free Dehairing of Animal Skin Using Collagenase-Free Alkaline Protease from Vibrio metschnikovii NG155

Bleach enhancement of mixed wood pulp by mixture of thermo-alkali-stable xylanase and mannanase derived through co-culturing of Alkalophilic Bacillus sp. NG-27 and Bacillus nealsonii PN-11

The Application of a combination of enzymes is the best alternative to reduce the use of chemicals in the paper industry. Bacillus sp. NG-27 and Bacillus nealsonii PN-11 are known to produce thermoalkali stable xylanse (X) and mannanase (M) respectively having potential for pulp biobleaching. The Present study, reports the production of a mixture of X + M by co-culturing of strains in SSF and standardizing its application for pulp biobleaching. Production of enzymes by co-cultivation in SSF was optimized by statistical methods. Substantial increase in the yield of enzymes; 3.61 fold of xylanase and 37.71 fold of mannanase was achieved. Application of enzyme cocktail for pulp biobleaching resulted in a 45.64% reduction of kappa number with 55 IU g^-1odp of enzyme dose (xylanase:mannanase; 3:1) at pH 8.0 in 1h at 65 °C along with significant increase in brightness (11%) and whiteness (75%). The Same quality of paper as made up from chemical treated pulp can be made from enzyme-treated pulp with 30% less use of chlorine. Structural analysis of enzyme-treated pulp showed dissolution of hemicellulose as indicated by pores, cracks and increased roughness all over the surface. Cocktail of X + M produced economically in a single fermentation having all the requisite characteristics for pulp biobleaching is a highly suitable candidate for application in the pulp and paper industry.

Microbial lipases and their industrial applications: a comprehensive review

Lipases are very versatile enzymes, and produced the attention of the several industrial processes. Lipase can be achieved from several sources, animal, vegetable, and microbiological. The uses of microbial lipase market is estimated to be USD 425.0 Million in 2018 and it is projected to reach USD 590.2 Million by 2023, growing at a CAGR of 6.8% from 2018. Microbial lipases (EC 3.1.1.3) catalyze the hydrolysis of long chain triglycerides. The microbial origins of lipase enzymes are logically dynamic and proficient also have an extensive range of industrial uses with the manufacturing of altered molecules. The unique lipase (triacylglycerol acyl hydrolase) enzymes catalyzed the hydrolysis, esterification and alcoholysis reactions. Immobilization has made the use of microbial lipases accomplish its best performance and hence suitable for several reactions and need to enhance aroma to the immobilization processes. Immobilized enzymes depend on the immobilization technique and the carrier type. The choice of the carrier concerns usually the biocompatibility, chemical and thermal stability, and insolubility under reaction conditions, capability of easy rejuvenation and reusability, as well as cost proficiency. Bacillus spp., Achromobacter spp., Alcaligenes spp., Arthrobacter spp., Pseudomonos spp., of bacteria and Penicillium spp., Fusarium spp., Aspergillus spp., of fungi are screened large scale for lipase production. Lipases as multipurpose biological catalyst has given a favorable vision in meeting the needs for several industries such as biodiesel, foods and drinks, leather, textile, detergents, pharmaceuticals and medicals. This review represents a discussion on microbial sources of lipases, immobilization methods increased productivity at market profitability and reduce logistical liability on the environment and user.

Recombinant expression and molecular engineering of the keratinase from Brevibacillus parabrevis for dehairing performance

Keratinase is capable of distinctive degradation of keratin, which provides an eco-friendly approach for keratin waste management towards sustainable development. In this study, the recombinant keratinase (KERBP) from Brevibacillus parabrevis was successfully expressed in Escherichia coli. The purified KERBP had the specific activity of 6005.3 U/mg. It showed remarkable tolerance to various surfactants and also no collagenolytic activity. However, the moderate thermal stability limited its further application. Thus, protein engineering was further adopted to improve its stability. The variants of T218S, S236C and N181D were constructed by site-directed mutagenesis and combinatorial mutagenesis. Compared with the wild type, the t_1/2 at 60 °C for the variants T218S, S236C and N181D were 3.05-, 1.18- and 1-fold increase, respectively. Moreover, the double variants N181D-T218S and N181D-S236C significantly improved thermostability with 5.1 and 2.9 °C increase of T₅₀, and prolonging t_1/2 at 60 °C with 4.09 and 1.54-fold, respectively. And the catalytic efficiency of the T218S and N181D-T218S variants was also significantly improved. Furthermore, the keratinase displayed favorable ability to dehair wool from skin within 7 h, which showed potential in leather dehairing. Our work contributes to a further insight into the thermostability of keratinase and offers a promising alternative for industrial leather application.

Optimized production of extracellular alkaline protease from Aspergillus tamarii with natural by-products in a batch stirred tank bioreactor

Proteolytic enzymes are one of the significant commercially manufactured enzymes. The manufacture of extracellular alkaline protease by Aspergillus tamarii MTCC5152 was explored using several agricultural by-products as substrates viz., cottonseed meal, wheat bran, skimmed milk and soya flour in submerged fermentation, were found to be efficient for enzyme production and commercially significant. Response surface methodology (RSM) is a statistics-based experimental design, sourced to explore the impact of physical parameters on the manufacture of protease from A. tamarii in a batch stirred tank bioreactor (STBR). The four substantial variables (pH, temperature, inoculum size, and agitation) were carefully chosen for optimization analyses and the statistical pattern was created using a central composite design and the quadratic model has been developed. The optimum conditions for protease production (1.51 U mL^-1) where: pH 6.4, temperature 27 °C, inoculum size 2.6%, and agitation 327 rpm. The analysis revealed that the anticipated values were in accord with trial data with a correlation coefficient of 0.969.

Development of nano-silver alkaline protease bio-conjugate depilating eco-benign formulation by utilizing potato peel based medium

A new bio-conjugate nano-silver enzyme conjugate complex (BC-nAg-Akp) was formulated containing alkaline protease (Akp). The present research involved synthesis of nAg particles in acetone concentrated enzyme sol using 0.005 M AgNO₃ solution formed within interaction time of 24 h through photo catalysis. The BC-nAG-Akp composite exhibited 1.9-fold increase in enzyme activity. The formulation was characterized using techniques viz., SEM, SEM-EDS, TEM, and DLS spectroscopy. The TEM analysis revealed synthesis of silver nano rods with size dimensions ranging from 40 to 80 nm. Likewise, the mean hydrodynamic diameter was 114 nm with polydispersity index of 0.260 and had the largest diffusion constant of 4.28 × 10⁸ amongst the three forms of the formulation (crude, acetone concentrated and partially purified) on DLS characterization. The SEM-EDS analysis showed occurrence of 18.32 and 3.79%weight and %atom of Ag element respectively. The prepared formulation was investigated for its dehairing performance. The ideal dehairing was achieved at 37 °C after 12 h of treatment. The histopathological studies revealed that complete dehairing with minimal rarefication was achieved and was found perform better compared to the commercial Akp and control (crude enzyme) formulations.

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.

Cloning, expression, and characterization of an alkaline protease, AprV, from Vibrio sp. DA1-1

A novel alkaline protease (named AprV) gene from Vibrio sp. DA1-1 was cloned and expressed in Escherichia coli BL21 (DE3) pLysS. The sequence analysis showed the highest homology of 68% with the characterized protease from Alkalimonas collagenimarina AC40^T. The recombinant AprV was purified with the molecular weight of 28 kDa. The optimum temperature and pH were determined to be 55 °C and 10.0, respectively. The enzyme activity was slightly enhanced by Ca²⁺, Mg²⁺, Zn²⁺, Ba²⁺, and, however, was highly inhibited by Sn²⁺ and EDTA. The AprV was stable in the presence of some surfactants and oxidizing agents, such as 1% Tween 20-80, 1% JFC-2, and 5% JFC-2. Casein was found to be the ideal substrate with specific activity of 1139 U/mg. Moreover, we found that AprV (10,000 U), together with commercial detergent, could completely remove the blood on the cotton. Furthermore, AprV also demonstrated dehairing activity on goat and bull skin. These results indicated that the alkaline protease AprV might be a potential candidate for applications in the detergent and leather industries.

Microbial Keratinases: Enzymes with Promising Biotechnological Applications

Keratin is a complex and structurally stable protein found in human and animal hard tissues, such as feathers, wool, hair, hoof and nails. Some of these, like feathers and wool, represent one of the main sources of protein-rich waste with significant potential to be transformed into value-added products such as feed, fertilizers or bioenergy. A major limitation impeding valorization of keratinous substrates is their recalcitrant structure and resistance to hydrolysis by common proteases. However, specialized keratinolytic enzymes produced by some microorganisms can efficiently degrade these substrates. Keratinases have already found a purpose in pharmaceutical, textile and leather industries. However, their wider implementation in other processes, such as cost-effective (pre)treatment of poultry waste, still requires optimization of production and performance of the available enzymes. Here we present a comprehensive review covering molecular properties and characteristics of keratinases, their classification, traditional and novel approaches in discovery of novel enzymes, production, characterization, improvement and biotechnological applications.

Proteolytic and amylolytic enzymes from a newly isolated Bacillus mojavensis SA: Characterization and applications as laundry detergent additive and in leather processing

The present work aims to study the simultaneous production of highly alkaline proteases and thermostable α-amylases by a newly isolated bacterium Bacillus mojavensis SA. The optimum pH and temperature of amylase activity were 9.0 and 55°C, respectively, while those of the proteolytic activity were 12.0 and 60°C, respectively. Both α-amylase and protease enzymes showed a high stability towards a wide range of pH and temperature. Furthermore, SA crude enzymes were relatively stable towards non-ionic (Tween 20, Tween 80 and Triton X-100) and anionic (SDS) surfactants, as well as oxidizing agents. Both activities were improved by the presence of polyethylene glycol 4000 and glycerol. Additionally, the crude enzymes showed excellent stability against various solid and liquid detergents. Wash performance analysis revealed that the SA crude enzymes exhibited a remarkable efficiency in the removal of a variety type of stains, such as blood, chocolate, coffee and oil. On the other side, SA proteases revealed a potential dehairing activity of animal hide without chemical assistance or fibrous proteins hydrolysis. Thus, considering their promising properties, B. mojavensis SA crude enzymes could be used in several biotechnological bioprocesses.

Biochemical characterization of a novel surfactant-stable serine keratinase with no collagenase activity from Brevibacillus parabrevis CGMCC 10798

Dehairing is a high pollution process in leather industry. Conventionally, the lime-sulfide mediated chemical process for dehairing would lead to the discharge of pollutants and corrosion of industrial equipment. Concerning these problems, keratinase has become a promising candidate for dehairing process in recent years. In this study, a keratinase-producing bacterium was isolated from sheepfold soil and identified as Brevibacillus parabrevis CGMCC 10798 based on the biochemical characteristics and molecular identification. The keratinase was purified to electrophoretic homogeneity with 17.19% of recovery, 13.18 folds of purification and an estimated molecular weight of 28kDa. The enzyme exhibited high keratinase activity and no collagenase activity. Besides, the keratinase showed optimal activity at 60°C and pH 8.0. The enzyme activity could be significantly increased in the presence of Na⁺ and Ca²⁺. And it was inhibited by EDTA, and PMSF, which indicated that the keratinase belongs to serine-metallo protease. The enzyme could remain stable in the presence of surfactants. Especially, 5mM Tween 40 and Triton 100 could improve the activity by 11% and 30%, respectively. Moreover, B. parabrevis keratinase could completely dehair goat wool within 7h, which indicated its application potential in leather industry.