A psychrotolerant strain of Serratia marcescens (MTCC 4822) produces laccase at wide temperature and pH range.

Gaurav Singh Kaira,Anita Pandey,Kusum Dhakar

doi:10.1186/s13568-014-0092-1

Gaurav Singh Kaira, Anita Pandey + Show 1 more

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https://doi.org/10.1186/s13568-014-0092-1

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Abstract

A psychrotolerant bacterial strain of Serratia marcescens, originally isolated from a glacial site in Indian Himalayan Region (IHR), has been investigated for laccase production under different culture conditions. The bacterial strain was found to grow between 4 to 45°C (opt. 25°C) and 3 to 14 pH (opt. 5 pH) on prescribed growth medium, coinciding with production of laccase in laccase producing medium. However, the production of laccase was more consistent toward alkaline pH. Laccase enzyme was partially purified using gel filtration chromatography. The molecular mass of laccase was determined ~53 kDa on native PAGE. The Km and Vmax values were determined to be 0.10 mM and 50.00 μM min−1, respectively, with ABTS. Inoculum size (4.0% v/v at 1.5 O.D.) resulted in significantly higher production of laccase. Carbon and nitrogen sources also affected the laccase production significantly. All the carbon sources enhanced laccase production, xylose being the best enhancer (P < 0.01). Among nitrogen sources, organic sources were found to act as inhibitors (P < 0.01), and among the in-organic sources only sodium nitrate enhanced the laccase production. Low molecular weight organic solvents significantly (P < 0.01) enhanced laccase production up to 24 h of incubation with a decline in later incubation period. Production of laccase by the psychrotolerant bacterium in wide range of temperature and pH is likely to have inference in biotechnological processes.

Highlights

Laccases are multicopper oxidases that catalyze oxidation of an extensive array of recalcitrant phenolic and nonphenolic compounds with simultaneous reduction of molecular oxygen to water (Rivera-Hoyos et al 2013)
Catalytic diversity of laccases are exploited for a number of industrial and environmental applications such as dye effluent decolorization, bio-bleaching, xenobiotics bioremediation, biosensors and food industry (Couto and Herrera 2006)
The fungal laccases are known with their optimum activity between pH 2.0-4.0, that can be attributed to their growth adaptation towards acidic pH

Summary

Introduction

Laccases (benzenediol: oxygen oxidoreductase, EC 1.10.3.2) are multicopper oxidases that catalyze oxidation of an extensive array of recalcitrant phenolic and nonphenolic compounds with simultaneous reduction of molecular oxygen to water (Rivera-Hoyos et al 2013). Laccases have mainly been explored from fungal sources for their various applications, especially towards the lignin depolymerization. The potential of fungal laccases are limited by the metabolic pH and salt intolerance. The fungal laccases are known with their optimum activity between pH 2.0-4.0, that can be attributed to their growth adaptation towards acidic pH. A need to increase this active pH range for laccase production through molecular engineering is being realized (Torres-Salas et al 2013). Relatively slow growth is another limitation towards the laccase production from fungal sources. In view of these limitations, laccase production from alternate sources, such as bacteria, is getting attention. Industrial scale-up of bacterial laccases is still riddled due to its extracellular location and tolerance to extreme

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