Optimized production of keratinolytic proteases from Bacillus tropicus LS27 and its application as a sustainable alternative for dehairing, destaining and metal recovery

The present study describes the isolation and characterization of Bacillus tropicus LS27 capable of keratinolytic protease production from Russell Market, Shivajinagar, Bangalore, Karnataka, with its diverse application. The ability of this strain to hydrolyze chicken feathers and skim milk was used to assess its keratinolytic and proteolytic properties. The strain identification was done using biochemical and molecular characterization using the 16S rRNA sequencing method. Further a sequential and systematic optimization of the factors affecting the keratinase production was done by initially sorting out the most influential factors (NaCl concentration, pH, inoculum level and incubation period in this study) through one factor at a time approach followed by central composite design based response surface methodology to enhance the keratinase production. Under optimized levels of NaCl (0.55 g/L), pH (7.35), inoculum level (5%) and incubation period (84 h), the keratinase production was enhanced from 41.62 U/mL to 401.67 ± 9.23 U/mL (9.65 fold increase) that corresponds to a feather degradation of 32.67 ± 1.36% was achieved. With regard to the cost effectiveness of application studies, the crude enzyme extracted from the optimized medium was tested for its potential dehairing, destaining and metal recovery properties. Complete dehairing was achieved within 48 h of treatment with crude enzyme without any visible damage to the collagen layer of goat skin. In destaining studies, combination of crude enzyme and detergent solution [1 mL detergent solution (5 mg/mL) and 1 mL crude enzyme] was found to be most effective in removing blood stains from cotton cloth. Silver recovery from used X-ray films was achieved within 6 min of treatment with crude enzyme maintained at 40 °C.

Production and characterization of a novel thermo- and detergent stable keratinase from Bacillus sp. NKSP-7 with perceptible applications in leather processing and laundry industries

Keratinase has the ability to degrade the recalcitrant keratinous wastes that cannot be degraded by conventional proteases. The present study describes a novel hyperstable keratinolytic enzyme from Bacillus sp. NKSP-7, which has excellent efficiency of keratin-feather biodegradation, washing and dehairing. The production of extracellular keratinase was improved by 3.02-fold through optimization of various parameters. Purified keratinase (25 kDa) showed optimal activity at 65 °C and pH 7.5, and displayed stability over a range of pH (5.5-9.5) and temperature (20-60 °C) for 8 h. No conspicuous effect was perceived with various chemicals and organic solvents, however, the catalytic efficiency was enhanced in the presence of Ca²⁺, Cd²⁺, Na⁺, Mn²⁺, sodium sulfite, and β-mercaptoethanol. The enzyme was completely inhibited by phenylmethanesulfonyl fluoride (PMSF), suggesting that this keratinase belongs to serine protease family. It displayed prodigious stability and compatibility to salinity and commercial detergents. Enzyme exhibited great substrate specificity but high affinity was observed with keratin-rich substrates. Crude and purified keratinase revealed perceptible potential for destaining of blood-stained fabric (10 min), and dehairing of hide (8 h) without any damage. All these auspicious features make this enzyme a promising candidate for various industrial applications, especially in keratin-waste management, detergent formulations and leather processing.

Destaining Coomassie Brilliant Blue-Stained Sodium Dodecyl Sulfate-Polyacrylamide Protein Gels Using a Household Detergent

We report here a one-step method using the household detergent Vim Ultra to destain sodium dodecyl sulfate-polyacrylamide protein gels stained with Coomassie Brilliant Blue. This method, originally described by Pal and group, uses a 5% suspension of the detergent to destain gels efficiently. This method is cheap and user-friendly compared to the commonly used methanol-acetic acid-water containing destaining solvent.

Long-Term Monokaryotic Cultures of Pleurotus ostreatus var. florida Produce High and Stable Laccase Activity Capable to Degrade ß-Carotene

An extracellular laccase (Lacc10) was discovered in submerged cultures of Pleurotus ostreatus var. florida bleaching ß-carotene effectively without the addition of a mediator (650 mU/L, pH 4). Heterologous expression in P. pastoris confirmed the activity and structural analyses revealed a carotenoid-binding domain, which formed the substrate-binding pocket and is reported here for the first time. In order to increase activity, 106 basidiospore-derived monokaryons and crosses of compatible progenies were generated. These showed high intraspecific variability in growth rate and enzyme formation. Seventy-two homokaryons exhibited a higher activity-to-growth-rate-relation than the parental dikaryon, and one isolate produced a very high activity (1800 mU/L), while most of the dikaryotic hybrids showed lower activity. The analysis of the laccase gene of the monokaryons revealed two sequences differing in three amino acids, but the primary sequences gave no clue for the diversity of activity. The enzyme production in submerged cultures of monokaryons was stable over seven sub-cultivation cycles.

Application of Heat to Quickly Stain and Destain Proteins Stained with Coomassie Blue

Proteins separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis have been visualized reliably by staining with Coomassie Brilliant Blue. In this chapter, we show that it is possible to drastically reduce protein staining and destaining time, while simultaneously increasing detection sensitivity, with the application of heat. It took 5 min to stain proteins at 55, 62.5, or 70 °C for a 1.5 mm gel, while it took 45, 45, and 20 min respectively for destaining. The time for staining was 1 min for a 0.8 mm gel at 65 °C, 2 min at 60 °C and 5 min at 55 °C. The destaining of proteins separated on a 0.8 mm gel took 8, 15, and 20 min at 65, 60, and 55 °C respectively. Proteins can be stained and destained rapidly with the use of heat, while enhancing detection sensitivity.

Optimal parameters for laccase-mediated destaining of Coomassie Brilliant Blue R-250-stained polyacrylamide gels

The data presented in this article are related to the research article entitled “Destaining of Coomassie Brilliant Blue R-250-stained polyacrylamide gels with fungal laccase” [1]. Laccase is a class of multicopper oxidases that can catalyze oxidation of recalcitrant dyestuffs. This article describes optimal parameters for destaining of polyacrylamide gels, stained with Coomassie Brilliant Blue R-250, with laccase from basidiomycete Cerrena sp. strain HYB07. Effects of laccase activity, mediator type and concentration, temperature and time on destaining of polyacrylamide gels were evaluated with respect to gel background intensity and protein band signals, and the optimal destaining effects were obtained with 15 U mL⁻¹ laccase and 2 μM ABTS at 37 °C after 2 h.

Production, Purification, and Biochemical Characterization of Thermostable Metallo-Protease from Novel Bacillus alkalitelluris TWI3 Isolated from Tannery Waste

Protease enzymes in tannery industries have enormous applications. Seeking a potential candidate for efficient protease production has emerged in recent years. In our study, we sought to isolate proteolytic bacteria from tannery waste dumping site in Tamilnadu, India. Novel proteolytic Bacillus alkalitelluris TWI3 was isolated and tested for protease production. Maximum protease production was achieved using lactose and skim milk as a carbon and nitrogen source, respectively, and optimum growth temperature was found to be 40 °C at pH 8. Protease enzyme was purified using ammonium sulfate precipitation method and anion exchange chromatography. Diethylaminoethanol (DEAE) column chromatography and Sephadex G-100 chromatography yielded an overall 4.92-fold and 7.19-fold purification, respectively. The 42.6-kDa TWI3 protease was characterized as alkaline metallo-protease and stable up to 60 °C and pH 10. Ca(2+), Mn(2+), and Mg(2+) ions activated the protease, while Hg(2+), Cu(2+), Zn(2+), and Fe(2+) greatly inhibited it. Ethylenediaminetetraacetic acid (EDTA) inhibited TWI3 protease and was activated by Ca(2+), which confirmed that TWI3 protease is a metallo-protease. Moreover, this protease is capable of dehairing goat skin and also removed several cloth stains, which makes it more suitable for various biotechnological applications.

Destaining of Coomassie Brilliant Blue R-250-stained polyacrylamide gels with fungal laccase

An enzyme-based method for destaining polyacrylamide gels stained with Coomassie Brilliant Blue R-250 is described. Distilled water supplemented with diluted fermentation broth of a laccase-producing white-rot fungus, Cerrena sp., was used for gel destaining, and a clear gel background was obtained in 2 h at 37 °C. Sensitivity of protein detection was 10 ng. The method did not require organic solvents or changing the destaining solution. Due to simultaneous gel destaining and dye decolorization, the colorless destaining solution can be disposed of directly. Laccase destaining of polyacrylamide gels was simple, efficient, and environmentally friendly.