Response Surface Methodology Mediated Modulation of Laccase Production by Polyporus arcularius

Abstract

Screening of thirteen mushroom fungal isolates collected from Alagar Hill and Thandikudi Hill of Tamil Nadu, India, for laccase production revealed the high laccase production potential of the isolate MI 51. The mushroom isolate MI 51 was identified as Polyporus sp., based on sporophore (fruiting body) morphology and spore characteristics. Molecular identification of the fungal isolate MI 51 using primer ITS1 and ITS4 showed that isolate MI 51 shared 98 % sequence similarity with Polyporus arcularius, a basidiomycete fungus. Initial screening of production parameters using Plackett–Burman design helped in identifying the system variables/parameters which directly influenced laccase production. Laccase production by P. arcularius was optimized using central composite design (CCD) of experiments and response surface methodology (RSM) by studying influence of the growth supplements and media additives on modulating laccase production by P. arcularius. High laccase production by P. arcularius growing in basal salt medium, (9.30 IU/ml), was observed in 21 days of incubation. Results from experiments designed by CCD indicated that nearly threefold increase in laccase production (28.30 IU/ml) over the control experiments in basal salt medium could be obtained earlier at 15 days of incubation by increasing the content of the nitrogen source, yeast extract to 0.5 g/l, and by adding 250 μM CuSO4 to the basal salt medium. RSM plots showed high interaction between the variables, incubation time, yeast extract concentration, and CuSO4 concentration in the medium.