Abstract
Laccase production by a temperature and pH tolerant fungal strain (GBPI-CDF-03) isolated from a glacial site in Indian Himalayan Region (IHR) has been investigated. The fungus developed white cottony mass on potato dextrose agar and revealed thread-like mycelium under microscope. ITS region analysis of fungus showed its 100% similarity with Trametes hirsuta. The fungus tolerated temperature from 4 to 48°C ± 2 (25°C opt.) and pH 3–13 (5–7 opt.). Molecular weight of laccase was determined approximately 45 kDa by native PAGE. Amplification of laccase gene fragment (corresponding to the copper-binding conserved domain) contained 200 bp. The optimum pH for laccase production, at optimum growth temperature, was determined between 5.5 and 7.5. In optimization experiments, fructose and ammonium sulfate were found to be the best carbon and nitrogen sources, respectively, for enhancing the laccase production. Production of laccase was favored by high carbon/nitrogen ratio. Addition of CuSO4 (up to 1.0 mM) induced laccase production up to 2-fold, in case of 0.4 mM concentration. Addition of organic solvents also induced the production of laccase; acetone showed the highest (2-fold) induction. The study has implications in bioprospecting of ecologically resilient microbial strains.
Highlights
IntroductionLaccases (phenol oxidases; E.C. 1.10.3.2.), known as multicopper blue oxidases, belong to the oxidoreductase group of enzymes
Laccases, known as multicopper blue oxidases, belong to the oxidoreductase group of enzymes
A temperature and pH tolerant fungus isolated from a glacial site in Indian Himalayan Region (IHR) has been investigated for production of laccase at different physicochemical and nutritional conditions
Summary
Laccases (phenol oxidases; E.C. 1.10.3.2.), known as multicopper blue oxidases, belong to the oxidoreductase group of enzymes. They are glycoproteins carrying molecular mass between 50 kDa and 130 kDa [1]. Fungi, belonging to ascomycetes, deuteromycetes, and basidiomycetes, are known to produce laccases of ecological as well as biotechnological importance, such as biodegradation and bioremediation [1,2,3,4]. Laccases are responsible for various physiological functions in fungi [5] Due to their broad specificity toward substrate, they can oxidize a range of chemical compounds leading to various industrial applications [6]. A temperature and pH tolerant fungus isolated from a glacial site in Indian Himalayan Region (IHR) has been investigated for production of laccase at different physicochemical and nutritional conditions
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