Surfactant Jianqing Mildew Laccase Production In Solid State Fermentation And The Effect Of Degradation Of Phenol

Recently, the problem about the agricultural solid waste pollution has becomeincreasingly prominent in China. Every year, a large number of agricultural solid waste aregenerated, which lead to an enormous environmental pollution. In particular, the treatment ofcrop straw and other agricultural waste residues is more serious. The solid-state fermentationis considered as a useful process for the disposal of agricultural solid waste. Theselignocellulosic raw materials from agricultural residues are used to ferment, which not onlymay solve the energy crisis and environmental pollution, and also is the main tool for greenproduction.During the solid-state fermentation, the raw material is transformed through a variety ofbiological and biochemical processes in which enzymes play an important role. Many reportshave shown the stimulative effect of surfactants (nonionic and anionic) on the production andrelease of enzyme in solid-state fermentation. Surfactants(nonionic and ionic) are compoundsthat have both hydrophilic and hydrophobic radicles. It not only improve the permeability ofthe cell membrane to facilitate enzyme relese，but also increase the enzyme stability andprevent denaturation of enzymes during hydrolysis by desorbing it from substrate.Biosurfactant is a high surface-active agent synthesized by microorganism. Compared withchemical surfactant, biosurfactant has a low toxicity to ecological system of earth and can bebiodegraded by microorganism. Along with manganese peroxidase and lignin peroxidase,laccases are a type of lignin-modifying enzyme. Moreover, it also is the most reliable enzymefor phenolic removal. Because of its widespread application, it gradually attract greaterattention.In this study, SDS, Tween-80, Triton X-100, TS and RL were used as the modelsurfactants, Penicillium simplicissimum isolated from the soil used as the modelmicroorganism. Firstly, the effects of surfactants on simultaneous laccase production andactivity by Penicillium simplicissimum in the solid-state fermentation without phenol werestudied. In additon, the impact of chemical surfactants and biosurfactants on the phenolpolluted solid-state process also were study. These factors were determined, such as laccaseactivity, phenol degradation, fungal biomass and organic matter degradation.In the solid-state fermentation without phenol, the results showed that surfactants SDS,Triton X-100, Tween-80had some inhibitory effect on laccase production by Penicillium simplicissimum, and brought forward the laccase peak periods in various degrees. The highestlaccase activities during the fermentation enhanced by2,1,0.5times by0.02%TS,0.06%TS,0.10%TS, respectively. With the increase of TS concentration, the ability of Penicilliumsimplicissimum to produce laccase decreased. RL at different concentrations could simulatelaccase activity in solid-state fermentation, following the order as0.010%RL>0.005%RL>0.015%RL. Tween-80and RL had a promotation on the fungal growth, and also enhance thedegradation of organic matter.In the solid-state fermentation polluted by phenol, the effects of three chemicalsurfactants and two biosurfactants on the production of laccase and the degradation of phenolby Penicillium simplicissimum were investigated. Firstly, the effects of phenol on thefermentation process were studied in the absence of surfactants. Then, a phenol concentrationof3mg/g in the fermentation was selected for detailed research with the addition ofbiosurfactants. The results showed that except for0.005%SDS, chemical surfactants atdifferent concentrations had certain inhibitory effects on the enzyme activity of laccase.However, biosurfactant TS and RL at different concentrations had stimulative effects on theenzyme activity of laccase. The highest laccase activities during the fermentation wereenhanced by163.7%,68.2%and23.3%by TS at concentrations of0.02%,0.06%and0.10%,respectively. The tendency of phenol degradation in the treatments with surfactants had somecommon characteristics with the development of laccase activities. As a result of theenhanced laccase activity, the efficiency of phenol degradation was also improved by bothbiosurfactants. RL caused a significant increase of fungal biomass in the early stage of thefermentation, while TS had an inhibitory effect in the whole process. These results indicatedthat RL could mitigate the negative effects of phenol on fungal growth, and consequentlyimprove laccase production and phenol degradation in the solid-state fermentation.