Abstract
A novel laccase enzyme producing bacterium, Pseudomonas putida MTCC 7525, was isolated and subjected to optimization of laccase production. Maximum production (94.10 U/ml) was achieved at 30 1C and pH 8 (108 h incubation) with 10% skim milk and 1 mM sodium nitrate as additional nitrogen source. The laccase was purified by salt precipitation followed by ion exchange chromatography which showed 6.44 fold purification. The purified enzyme had optimal activity at pH 8.0 and 40 1C, and showed stability in DMSO retaining more than 85% of original activity. In presence of manganese and cadmium, enzyme retained 495% and 92% activity, respectively. The molecular weight of laccases was 39.5 kDa and activity was inhibited by pCMB (93%). The synthetic dyes (0.02%) and industrial effluents (10%) were decolorized to 7493 and 5868%, respectively when treated with culture of P. putida. However, the culture supernatant of P. putida showed about 3694 and 1686% decolorization of synthetic dyes and effluents, respectively within 24 h of incubation. (C) 2013 Elsevier Ltd. All rights reserved.