Production of laccase from Trametes trogii TEM H2: a newly isolated white‐rot fungus by air sampling

Abstract

This work represents the first report of isolation of potential laccase producers by air sampling using media supplemented with 2,2-azinobis (3-ethylbenzothiazoline-6-sulfonate) and guaiacol for laccase production and secretion indicators. Nine fungal isolates showed positive reactions with 2,2-azinobis (3-ethylbenzothiazoline-6-sulfonate) and guaiacol. The isolate named TEM H2 exhibited the largest and intensive oxidation zones with 2,2-azinobis (3-ethylbenzothiazoline-6-sulfonate) (85 mm) and guaiacol (66 mm) and therefore it was selected for detailed investigations. The strain was identified as Trametes trogii TEM H2 due to the morphological characteristics and the comparison of internal transcribed spacer ribosomal DNA gene sequences. The laccase production was screened in different liquid cultures. The best laccase production medium was determined as soluble starch yeast extract medium in which laccase production was reached to a maximum level (989.6 U l(-1) ) on the 8(th) day of cultivation. Effects of different initial pH values on laccase production were tested. Optimum pH value for laccase production in soluble starch yeast extract medium was determined as pH 3.0 with 15425.0 U l(-1) laccase production at 12(th) day of cultivation. In addition, effects of eight inducers (veratryl alcohol, ferulic acid, 1-Hydroxybenzotriazole, syringic acid, 2,2-azinobis (3-ethylbenzothiazoline-6-sulfonate), 1 mmol l(-1) CuSO(4) , 3% ethanol, guaiacol) were examined. Only cultures with 2,5-xylidine exhibited 1.9 fold increase in laccase activity reaching to 28890.0 U l(-1).