Determination of the effect of RBBR on laccase activity and gene expression level of fungi in lichen structure

Improved laccase production by Trametes versicolor using Copper-Glycyl-L-Histidyl-L-Lysine as a novel and high-efficient inducer

A highly efficient strategy using Copper-Glycyl-L-Histidyl-L-Lysine (GHK-Cu) as a novel inducer was developed to enhance laccase production by Trametes versicolor. After medium optimization, laccase activity increased by 12.77-fold compared to that without GHK-Cu. The laccase production of 1113.8 U L-1 was obtained by scaling-up culture in 5-L stirring tank. The laccase production induced by CuSO4 was poorer than that of GHK-Cu at the same mole concentration. GHK-Cu could increase the permeability of cell membrane with less damage, and it facilitated the adsorption, accumulation, and utilization of copper by fungal cells, which was beneficial for laccase synthesis. GHK-Cu induced better expression of laccase related genes than that of CuSO4, resulting in higher laccase production. This study provided a useful method for induced production of laccase by applying GHK chelated metal ion as a non-toxic inducer, which reduced the safety risk of laccase broth and provided the potential application of crude laccase in food industry. In addition, GHK can be used as the carrier of different metal ions to enhance the production of other metalloenzymes.

Mold resistance of bamboo after laccase-catalyzed attachment of thymol and proposed mechanism of attachment

Laccase-catalyzed attachment of functional molecules onto the surface of bamboo represents an alternative, green approach to improve performance. Although treatment of bamboo with thymol improved resistance to mold, using laccase to fix the same concentration of thymol to the surface of the bamboo could increase both the antifungal activity and resistance to leaching. Leaching of thymol was reduced by as much as 48.4% when laccase was used in thymol fixation. To make clear the mechanisms of fixation, reaction of thymol catalyzed with laccase, was investigated using Fourier-transform infrared spectroscopy, ¹H-NMR, high-resolution mass spectrometry and thermogravimetric analysis, respectively. Results show that thymol oligomer (l-thymol) was formed with ether linkages, which resist water leaching. Although further confirmatory studies are needed, it seems that ether linkages were the main connection of thymol to lignin. This study demonstrates that laccase catalysis is a promising strategy to functionalize the surface of bamboo in order to bestow new properties suitable for a wide range of applications.

Schematic diagram of laccase-catalysed fixation of natural antimicrobial phenol to bamboo.