A novel extracellular thermo-alkali-stable laccase from Bacillus tequilensis SN4 (SN4LAC) was purified to homogeneity. The laccase was a monomeric protein of molecular weight 32 KDa. UV-visible spectrum and peptide mass fingerprinting results showed that SN4LAC is a multicopper oxidase. Laccase was active in broad range of phenolic and non-phenolic substrates. Catalytic efficiency (k cat/K m) showed that 2, 6-dimethoxyphenol was most efficiently oxidized by the enzyme. The enzyme was inhibited by conventional inhibitors of laccase like sodium azide, cysteine, dithiothreitol and β-mercaptoethanol. SN4LAC was found to be highly thermostable, having temperature optimum at 85°C and could retain more than 80% activity at 70°C for 24 h. The optimum pH of activity for 2, 6-dimethoxyphenol, 2, 2′-azino bis[3-ethylbenzthiazoline-6-sulfonate], syringaldazine and guaiacol was 8.0, 5.5, 6.5 and 8.0 respectively. Enzyme was alkali-stable as it retained more than 75% activity at pH 9.0 for 24 h. Activity of the enzyme was significantly enhanced by Cu2+, Co2+, SDS and CTAB, while it was stable in the presence of halides, most of the other metal ions and surfactants. The extracellular nature and stability of SN4LAC in extreme conditions such as high temperature, pH, heavy metals, halides and detergents makes it a highly suitable candidate for biotechnological and industrial applications.

Degradation of residual lignin in kraft pulp by chemical bleaching is implicated in causing environmental pollution. The use of thermo- and alkali-tolerant bacterial laccases is considered to be important biological alternative to chemical processing. Laccases from Bacillus species have shown promise in this respect but their intracellular/spore bound presence make their industrial application economically unfeasible. We report here on a novel extracellular active thermo-alkali-stable laccase (SN4 laccase)  which is active at 90 °C and pH 8.0 using 2,6-dimethoxyphenol as substrate from Bacillus tequilensis SN4. SN4 laccase retained 27 % activity for 5 min at 100 °C and more than 80 % activity for 24 h at 70 °C. The enzyme is also stable at a higher pH (9.0–10.0). Enzyme production was optimized by submerged fermentation. Relatively high yields (18,356 nkats ml−1) of SN4 laccase was obtained in a medium containing 650 μM MnSO4, 350 μM FeSO4, and 3.5 % ethanol. A 764-fold increase in laccase activity was observed under optimal conditions. In addition, reduction in kappa number and increase in brightness of softwood pulp by 28 and 7.6 %, respectively, were observed after treatment with SN4 laccase without a mediator. When N-hydroxybenzotriazole was used as a mediator, the kappa number was decreased to 47 % and brightness was increased to 12 %.

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In the present study, an extracellular alkali stable laccase (Lac DS) from DS which has pH optima at 8.5 using-phenylenediamine (PPD) as substrate has been reported. Lac DS retained 70% activity for 4 h at pH 8.5 and 90% activity for 24 h at 55 °C. The enzyme yield was enhanced by optimization of fermentation conditions. A 746-fold increase in yield was observed under optimized conditions using 150 µM MgSO, 1.2% yeast extract, 0.35% tryptone, and 150 µM vanillic acid. Lac DS was used to polymerize natural dye precursor catechol, pyrogallol, syringaldehyde, syringic acid, ferulic acid and gallic acid to develop a range of natural hair colors such as black, golden yellow, and reddish brown. The results indicate that alkaline Lac DS is a suitable candidate to develop a user-friendly and commercially applicable hair dyeing process in the area of cosmetic industry.

Laccases are multicopper oxidases containing four copper atoms per monomer distributed in three redox sites. Because of its tremendous applications in different areas, isolation of new laccases with wide range of industrial implementation. The present study focuses on the optimization of laccase production from Bacillus sp. MSK-01 under solid state fermentation conditions using fruit juice waste as the substrate. MSKLAC was produced extracellularly by the bacteria. This laccase was able to oxidize ABTS and syringaldazine. Various nutritional and environmental factors were utilized for increasing the enzyme yield. Plackett Burman was used to study the influence of input parameters on laccase yield. Tween-80, initial moisture ratio and magnesium sulphate were the major influencing factor affecting laccase yield. Central composite design of RSM was used for the modelling of experiment. Desirability approach was used to optimize laccase yield. Maximum laccase yield of 1645 IUg −1 was obtained when 0.55% of tween -80, 1:2.34 initial moisture ratio and 300μM magnesium sulphate was used. A 470 fold increase in the yield of laccase from unoptimized condition was obtained.

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The objective of this work was to isolate a microorganism producing alkaline protease that can be used as an ecofriendly alternative to chemicals in dehairing process of leather manufacture. Alkaline protease producing bacterium Vibrio metschnikovii NG155 was isolated from soil samples of leather industry. The protease was highly effective in dehairing of goat skin, completely eliminating the use of lime and sulfide. Histological studies of the skin after dehairing showed that the enzyme did not damage the collagen layer and brought good fiber opening. Absence of collagenase activity was confirmed by reacting pure collagen with the enzyme and analyzing it on SDS PAGE, which showed no degradation of collagen. The enzyme was stable in a wide range of pH (7-11) and temperature (10-50°C), which makes it suitable for industrial application.