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BioMed Research International
Vol. 2016, 2016, Pages: 1-11

Isolation and Physicochemical Characterization of Laccase from Ganoderma lucidum-CDBT1 Isolated from Its Native Habitat in Nepal

Prabin Shresth Bishnu Joshi, Jarina Joshi, Rajani Malla, and Lakshmaiah Sreerama

Central Department of Biotechnology, Tribhuvan University, Kirtipur, Nepal.


At present, few organisms are known to and capable of naturally producing laccases and white rot fungi are one such group. In the present study, three fungal species, namely, Ganoderma lucidum-CDBT1, Ganoderma japonicum, and Lentinula edodes, isolated from their native habitat in Nepal were screened for laccase production, and G. lucidum-CDBT1 was found to express highest levels of enzyme (day 10 culture media showed 0.92IU/mg total protein or 92IU/mL laccase activity with ABTS as substrate). Lignin extracted from rice straw was used in Olga medium for laccase production and isolation from G. lucidum-CDBT1. Presence of lignin (5g/L) and copper sulfate (30μM) in the media increased the extracellular laccase content by 111% and 114%, respectively. The laccase enzyme produced by G. lucidum-CDBT1 was fractionated by ammonium sulfate and purified by DEAE Sepharose anion exchange chromatography. The purified enzyme was found to have a molecular mass of 43kDa and exhibits optimal activity at pH 5.0 and 30°C. The isolated laccase was thermally stable for up to 70°C for 1h and exhibited broad pH stability. The kinetic constants, Km, Vmax, and Kcat , determined using 2,2′-azinobis-(-3-ethylbenzothiazoline-6-sulfonic acid) as substrate were found to be 110μM, 36μmol/min/mg, and 246min-1, respectively. The isolated thermostable laccase will be used in future experiments for delignification process.


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