碳质纳米材料与枝孢菌KR14的相互影响研究

The interaction between carbonaceous nanomaterials(CNMs) and the fungi Cladosporium sp.

碳质纳米材料(Carbon Nanomaterials, CNMs)因具有独特的电学及光学等性质而引起了人们的广泛关注,从而被大量使用并释放到环境中,进而影响生态系统环境及生物化学过程,但目前有关CNMs与环境微生物相互作用的研究鲜见报道.因此,本文研究了枝孢菌KR14(Cladosporium sp.)与3种CNMs(单壁碳纳米管(SWCNTs)、石墨烯(Graphene)和氧化石墨烯(GO))的相互作用.结果表明,CNMs的加入促进了3种非特异性酶(漆酶、锰过氧化物酶和木质素过氧化物酶)活性增加,其中,对锰过氧化物酶(MnP)活性的促进作用最为显著,18 d最高增加26.1%.在3种类型的CNMs中,SWCNTs对MnP活性刺激最佳,GO最弱.木质素降解实验和电化学分析表明,CNMs可作为电子导体提高真菌胞外电子传递效率,进而提高KR14对木质素的降解.X射线光电子能谱(XPS)结果表明,除GO外,SWCNTs和石墨烯的氧碳比(O/C)均上升,二者表面发生变化.拉曼光谱(Raman)和傅立叶变换红外光谱(FTIR)结果表明,SWCNTs的I_D/I_G显著提高,无序性增加;石墨烯出现2D峰,即与KR14相互作用后有一定程度堆叠;KR14可引起CNMs结构转变.本研究结果有助于深入理解和评价环境中CNMs与真菌之间的相互作用关系及CNMs对真菌降解木质素和环境碳循环的影响.

Carbon nanomaterials(CNMs) have attracted extensive attention due to their unique electrical and optical properties, while they may affect ecosystem environment and biochemical processes when released into the environment. Little research has been done on the interactions between CNMs and environmental microbes. Here we investigated the interaction between the fungi Cladosporium sp.(KR14) and three CNMs(single-walled carbon nanotubes, graphene and graphene oxide). Results showed that the presence of CNMs promoted the activities of three non-specific enzymes(laccase, manganese peroxidase and lignin peroxidase), and the enzyme activity of manganese peroxidase increased significantly by 26.1% in 18 days. SWCNTs stimulated MnP activity most greatly among the three types of CNMs. Lignin degradation experiments and electrochemical analysis indicated that CNMs acted as an electron conductor to enhance the extracellular electron transfer of fungi and improve the degradation of lignin by KR14. Results of X-ray photoelectron spectroscopy(XPS) show that for SWCNTs and graphene the O/C increased while for GO the O/C decreased. Raman and Fourier transform infrared spectroscopy results show that ID/IG of SWCNTs increased, meaning that their disorder increased. The appearance of 2 D peaks of graphene probably resulted from a certain degree of stacking after interaction, indicating that KR14 caused the changes of CNMs surface structure. Our results contribute to the understanding of the interaction between CNMs and fungi in the environment and the effects of CNMs on fungal degradation of lignin and environmental carbon cycle.