Lignin Deagradating Performance Of Laccase In Reverse Micellar System

Lignin is an organic polymers of complex structure and it is extremely rich in nature. The characteristic that lignin is hard to degradate makes the degradation of lignin becomes the limiting element during the carbon cycle on the planet. Therefore, the degradation of lignin has important far-reaching significance. Because of the complex structure and the characteristics of extremely difficult for degradation, during treatment process of lignocellulose, the introduction of surfactants was always required to enhance the enzyme activities which have the degradation ability, However, excessive use of chemical surfactants would bring about serious pollution to the environment. Biosurfactants, as an environmentally friendly natural surfactant, obtain more potential advantage than chemical surfactant so that it is more popular with people. Lignin molecules is difficult to separate in a complete state, this research selected guaiacol, the guaiacyl model structure material of lignin molecules, as the object to undertake the study of enzymatic degradation activity of laccase.Study was divided into two parts. One part was undertaken in the aqueous environment to study the degradation of lignin by laccase. Lignin degradation reaction of laccase with one kind of surfactants (cationic surfactant CTAB, nonionic surfactant Tween80, anionic surfactant SDS/AOT and rhamnolipid biosurfactant) added in, separately. After analyzing the degradation rate of the substrate guaiacol in each reaction system, the advantages of biosurfactant were compared with the chemical surfactants, which provided the foundation for the second part. Part II of the study was undertaken in different reverse micellar system to study the degradation of lignin by laccase. In order to form a stableand efficient reverse micellar system, the moisture content (a key factor in building a reverse micelle system) was analyzed firstly:the activity of laccase was measured when different kind of water content was considered in constructing the inverse micellar system so that we could knew the moisture content value when the highest laccase activity was detected and we could thereby established a reverse micellar system with a relatively high laccase activity. The research on lignin degradation by laccase was carried out in that knid of system. By analyzing the degradation rate of the substrate, different degradation characteristics of laccase in reverse micellar systems could be obtained, in order that we could get the best reverse micellar system for lingnin degradation reaction by laccase.The results in this study showed that in aqueous environment, the addition of rhamnolipid during the degradation of lignin, degradation rate of the substrate and lacasse activity have been promoted stability and the promotion of both of the two elements increased with the more addition of surfactant. In the system with rhamnolipid added in, the degradation rate of the substrate were faster than that obtained in the system with the addition of chemical surface active agent in this study, ie, CTAB, Tween80and SDS. It was found that when the concentration of surfactants we added was1CMC in different groups of reverse micellar system, the degradation rate of the substrate showed the highest value, while too low or too high concentration of surfactant would both inhibit the degradation of the substrate. In addition, among the variety of inverse surfactant micelles systems, AOT and rhamnolipid system both belong to the same anionic surfactant, and substrate degradation rate in anionic surfactant micelles systems were higher than that in cationic and nonionic surfactant micelles system. What is more, in biosurfactants surfactant micelles systems, ie. with addition of rhamnolipid, the degradation of the subatrate was highest (57.56%),21.92%higher than that detected in the system with CTAB added in,20.16%higher than that with Tween-80and11.73%higher than that with AOT.