Manganese peroxidases(MnP)from Phanerochaete chrysosporium were adsorbed onto multi-walled carbon nanotubes(MWNT).Four different loadings of MnP on MWNTs were investigated,and the maximum enzyme loading of 47.5µg/mg of MWNTs was obtained in 12 h.The adsorbed MnP showed a catalytic activity of up to 0.1 U/mg of the weight of the system of MnP/MWNTs,with 23%of its original activity retained.The AFM image of the adsorbed enzymes indicated that a layer of MnP covered the surface of the MWNTs and retained its original three-dimensional shape.Amino-based nonspecific interactions may play the dominant role in the adsorption of MnP on MWNTs.
In order to achieve an innovative strategy to renew the biomass of Phanerochaete chrysosporium in an immobilized growth system which can maintain white-rot fungi biomass, a novel knotted cotton-thread carrier was designed and made. By using a high-speed stirring apparatus under the conditions of 1400 r/min stirring speed for 6 min, mycelia immobilized on the knotted cotton-thread carriers were exfoliated completely and homogenized to a proper size. Furthermore, the homogenized mycelia from the immobilized mycelia can resume their growth on the knotted cotton-thread carriers in agitated flask cultures. The average regrowth biomass on the new carriers and the reused carriers was 0.0171 g/carrier and 0.0314 g/carrier, respectively. It proves that the knotted cotton-thread carrier performs perfectly in homogening the immobilized mycelia to achieve the biomass renewal of P. chrysosporium in an immobilized growth system.
Immobilization of enzymes on mesoporous silicas (MS) allows for good reusability. MS with two-dimensional hexagonal pores in diameter up to 14.13 nm were synthesized using Pluronic P123 as template and 1,3,5-triisopropylbenzene as a swelling agent in acetate buffer. The surface of MS was modified by the silanization reagents 3-aminopropyltriethoxysilane. Lignin peroxidase (LiP) was successfully immobilized on the modified MS through covalent binding method by four agents: glutaraldehyde, 1,4- phenylene diisothiocyanate, cyanotic chloride and water-soluble carbodiimide. Results showed that cyanotic chloride provided the best performance for LiP immobilization. The loaded protein concentration was 12.15 mg/g and the immobilized LiP activity was 812.9 U/L. Immobilized LiP had better pH stability. Acid Orange II was used to examine the reusability of immobilized LiP, showing more than 50% of the dye was decolorized at the fifth cycle.
