Production of laccase without inducer by Chaetomium species isolated from Chettaba forest situated in the East of Algeria

Abstract

A positive laccase strain which showed a positive reaction with guaïacol was isolated from Chettaba Forest, which is situated in Constantine, the East of Algeria. It was identified as Chaetomium species (Ref 051A) according to the morphological and ribosomal internal transcribed spacer (ITS) DNA genomic sequence analysis. Laccase activity was determined by using 2,2-azinobis(3- ethylbenzthiazoline-6-sulfonate) diammonium salt (ABTS) as a substrate. Its highest activity was achieved by using potato dextrose broth (PDB) as a culture medium. Metal ion CuSO₄ had no positive effect on laccase production. The laccase activity obtained in submerged fermentation (20 L) was higher than that produced in Erlenmeyer flask (500 ml). The study of pH and temperature effects showed that pH optimum was 5 and 6, and temperature was 35°C. Laccase produced by Chaetomium spp. can be used in industrial production.

Keywords: Chaetomium species, guaïcol, laccase, 2,2-azinobis(3- ethylbenzthiazoline-6-sulfonate) diammonium salt (ABTS), submerged fermentation