Efficient production of laccases by Trametes sp AH28-2 in cocultivation with a Trichoderma strain

A biocontrol fungus isolated from rotting wood was identified as a Trichoderma strain (named as Trichoderma sp. ZH1) by internal transcribed spacer (ITS) sequences of rRNA genes. The laccase yield of Trametes sp. AH28-2 in cocultivation with Trichoderma sp. ZH1 reached 6,210 U l(-1), approximately identical to those induced by toxic aromatic inducers. Cocultures maintained 60-70 % of their highest laccase activity obtained at 5 days after inoculation of the biocontrol fungus, at least for 20 days. Furthermore, a novel laccase isozyme (LacC) was obtained through the fungal interactions. The molecular weight of LacC is about 64 kDa, and its isoelectric point is 6.6. The temperature and pH optimum for LacC to oxidize guaiacol are 55 degrees C and 5.0, respectively. LacC is stable both at 60 degrees C and pH 4.0-8.0. Furthermore, the K-m values of LacC for various substrates were also determined. Our work demonstrates a safe strategy for the production of industrial laccases, instead of the traditional method of chemical induction.