Versatility of methods for screening of laccase producing yeasts isolated from

Laccase is abenzenediol: oxygen oxidoreductase,(EC 1.10.3.2) belonging to the multinuclear coppercontainingoxidases; itcatalyzes the mono-electronicoxidation of various aromatic substrates at the expenseof molecular oxygen. In addition to plants and somebacteria,the enzyme has also been found in various basidiomycetous and ascomycetous fungi. Fungallaccases carry out a variety of physiological rolesincluding morphogenesis, fungal pathogen/ plant hostinteraction, stress defense and lignin degradation.Yeast strains were isolated from soil samples on YPGmedium supplemented with antibiotics. Differentindicator compounds including crystal violet (2.5μg/ml),guaiacol (0.01%) and tannic acid (0.5%) were individuallyadded to the separate appropriate solid media in orderto detect yeasts producing ligninolytic enzyme. Thoseisolates showed positive results on more than one typeof differential media were selected and characterizedbiochemically and identified by sequencing of D1/D2region of 26S rDNA.A total of 107 isolates were studied and among those70isolates (65%) showed positive results when crystal violetwas used as the indicator. Using each of guaiacol andtannic acid indicators, 37 isolates (34%) and 21 isolates(19%) showed positive results, respectively.Six isolates showed positive results for more than oneindicator were biochemically and molecularly identifiedas members ofCryptococcusspp. and Rhodotorulaspp..I Itwas shown that plate-test screening based on polymericdye compounds is an efficient way to track novel laccaseproducers.Efficacy of each screening method was verified and theimportance of concurrent usage of different procedureswere discussed.

کلیدواژه ها:

Laccase ، polymeric dye compounds ، yeast