Abstract

Lignin modifying enzyme (LME) activity [laccase, lignin peroxidase (LiP) and manganese peroxidase (MnP)] was studied in two indigenously isolated white rot fungi, Ganoderma species KX879638 and Lentinus species KY006984 under solid state fermentation (SSF) of wheat bran and saw dust supplemented with various non-ionic polysorbate surfactants (Tweens) and Triton X-100. Both fungal species proved to be highly ligninolytic and promising laccase producers. Their laccase activity increased many folds due to supplementation of substrates with surfactants. Among surfactants, Tween 20 was the best, giving 39180 IU/g laccase in Ganoderma spp. and 37780 IU/g in Lentinus spp. on wheat bran corresponding to 3.8- and 10.6-fold increase over control condition. Triton X-100 was the best surfactant providing 29380 and 19877 IU/g laccase activity in Ganoderma spp. and Lentinus spp. on saw dust amounting to 2.9- and 3.9-fold increase over control condition, respectively. Ganoderma spp. always produced more laccase than Lentinus spp. on supplemented substrates. Between substrates, laccase production on supplementation was always more on wheat bran than saw dust. LiP and MnP activities were very low in comparison with laccase in both fungi under control conditions (1.92 to 4.07 IU/g and 0.98 to 2.07 IU/g, respectively) and upon treatment with surfactants; they did not show an appreciable change, thus, supplementation mediated ratio between laccase to LiP/MnP was larger.

Key words: White rot fungi, solid state fermentation, surfactants, laccase, lignin peroxidase, manganese peroxidase.