title: Biochemical characteristics of a textile dye degrading extracellular laccase from a Bacillus sp. ADR.
abstract: Bacillus sp. ADR secretes an extracellular laccase in nutrient broth, and this enzyme was purified up to 56-fold using acetone precipitation and DEAE-cellulose anion exchange chromatography. The molecular weight of purified laccase was estimated to be 66 kDa using sodium dodecyl sulfate polyacrylamide gel electrophoresis. The purified laccase oxidized 2,6-dimethoxy phenol, o-tolidine, hydroquinone, L-DOPA and guaiacol. The optimum pH for oxidation of o-tolidine, 2,6-dimethoxy phenol and guaiacol were 3.0, 4.0 and 5.0, respectively. The purified laccase contained 2.7 mol/mol of copper. The laccase was stable up to 40 °C and within the pH range of 7.0-9.0. Well-known inhibitors of multicopper oxidases such as, sodium azide, L-cysteine and dithiothreitol showed significant inhibition of laccase activity. The purified enzyme decolorized structurally different azo dyes with variable decolorization rates and efficiencies of 68-90%. This study is useful for understanding the precise use of Bacillus sp. ADR in the decolorization of textile dyes containing industrial wastewater.
authors.affiliation: Division of Applied Life Sciences, Gyeongsang National University, 900 Gajwa-dong, Jinju, Gyeongnam 660-701, Republic of Korea. telkeaa@gmail.com
authors.forename: Amar A
authors.initials: AA
authors.lastname: Telke
authors.forename: Gajanan S
authors.initials: GS
authors.lastname: Ghodake
authors.forename: Dayanand C
authors.initials: DC
authors.lastname: Kalyani
authors.forename: Rhishikesh S
authors.initials: RS
authors.lastname: Dhanve
authors.forename: Sanjay P
authors.initials: SP
authors.lastname: Govindwar
mesh_terms: D001407:Bacillus / Q000187:drug effects / Q000201:enzymology*; D001673:Biodegradation, Environmental / Q000187:drug effects; D003116:Color; D004396:Coloring Agents / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004795:Enzyme Stability / Q000187:drug effects; D005110:Extracellular Space / Q000187:drug effects / Q000201:enzymology*; D006863:Hydrogen-Ion Concentration / Q000187:drug effects; D007220:Industrial Waste / Q000032:analysis*; D042845:Laccase / Q000037:antagonists & inhibitors / Q000302:isolation & purification* / Q000378:metabolism; D008670:Metals / Q000494:pharmacology; D010084:Oxidation-Reduction / Q000187:drug effects; D012492:Salts / Q000494:pharmacology; D013379:Substrate Specificity / Q000187:drug effects; D013696:Temperature; D013783:Textile Industry
chemical_list: D004396:Coloring Agents; D004791:Enzyme Inhibitors; D007220:Industrial Waste; D008670:Metals; D012492:Salts; D042845:Laccase