Studies On The Production Of Ligninolytic Enzyme System And Decolorization Of Direct Sky Blue5b Dye By Pleurotus Ostreatus In Liquid Irce Straw Medium

The production of ligninolytic enzyme system and decolorization rate of directsky blue5B by Pleurotus ostreatus in liquid-state rice straw medium were studied.Through adding the exterior substances in the fermentation systems, we try toexplore the means of increasing of ligninolytic enzyme system activity anddecolorization rate of direct sky blue5B, and seek the relationship between theactivities of ligninolytic enzyme system and decolorization rate of direct sky blue5B. The purpose of this work was to search a new method for the decolorization ofdirect sky blue5B, and provide a new biological utilization for rice straw. The mainresearch results were presented as following:1.The effects of direct sky blue5B dye at different concentrations（100mg/L,200mg/L,400mg/L,600mg/L and800mg/L）on the mycelia production anddecolorization rate of direct sky blue5B dye with different concentrations（100mg/L,150mg/L,200mg/L,250mg/L,300mg/L and400mg/L）under thesingle-strain and mixed-strain fermentation of P. ostreatus and Lentinus edodes inliquid-state medium were studied firstly. The results showed:100mg/L-400mg/Lof direct sky blue5B increased significantly the dry weight of mycelia under thesingle-strain and mixed-strain fermentation of P. ostreatus and L. edodes, and thegrowth of mycelia was inhibited significantly when the dye concentrations were600mg/L and800mg/L respectively. The dry weight of mycelia was the highestwhen200mg/L of direct sky blue5B was inoculated into the single-strainfermentation system of P. ostreatus and L. edodes，and the dry weight of myceliawas also reached the highest when the dye concentrations was400mg/L under themixed-strain fermentation of P. ostreatus and L. edodes. In the three kinds offermentation systems, the decolorization rate of the direct sky blue5B dye wasdecreased under high concentrations, and the decolorization rate was increasing with the rising time of fermentation. Of the all concentrations, the decolorizationrate was the best under the three kinds of fermentation system when theconcentration of direct sky blue5B was100mg/L; when the dye concentration thewas100mg/L, the decolorization rate in the single-strain fermentation system of P.ostreatus was87.9%, which was better than in the single-strain fermentation of L.edodes and mixed-strain fermentation of P. ostreatus and L. edodes, therefore, P.ostreatus was selected as the fermentation strains in the following research.2.The effects of metal irons (Cu²⁺, Mn²⁺, Al³⁺, Zn²⁺and Fe³⁺, theirconcentration were all5mM), organic acid and tween80on the activity ofligninolytic enzyme system and the decolorization rate of direct sky blue5Bdye（100mg/L） under the single-strain fermentation of P. ostreatus in liquid-staterice straw media. The results showed that: compared to the control （without addingmetal ions）, Cu²⁺, Mn²⁺and Al³⁺all increased significantly the activities of MnP andLac. The activity of MnP was2.49times of the contrast when5mM Mn²⁺wasadded into the medium; but Zn²⁺decreased significantly the activity of Lac.1mM,3mM,5mM glycollate acid and1mM oxalate acid improved dramatically theactivity of Lac respectively compared to the control, and when1mM glycollateacid was added into the medium, the Lac activity was the highest （745U/L）, whichwas382U/L higher than the control;1mM,3mM glycollate acid and1mMoxalate acid all enhanced significantly the activity of MnP, and the most activity ofMnP was obtained when adding1mM glycollate acid.0.05%,0.1%and0.15%tween80all increased significantly the activity of Lac respectively, and the activityof Lac reached to705U/L when0.1%tween80was added, which was1.96timesof the control;0.1%,0.15%and0.20%tween80all enhanced significantly theactivity of MnP, the peak activity was on8thday, and the best suitable concentrationof tween80was0.15%.Cu²⁺，Mn²⁺and Al³⁺also increased the decolorization rate of direct sky blue5B significantly. Among them, Cu²⁺had the best effect and the highestdecolorization rate reached to91.5%, which was13.9%higher than the control.Compared the control, Fe³⁺had no difference on the decolorization rate of directsky blue5B, but Zn²⁺decreased the decoloring ability of P. ostreatus significantly. 3mM glycollate acid promoted the decoloring effect of direct sky blue5Bremarkably compared to the control, the highest decolorization rate was94.6%,which was13.1%higher than the control.1mM and5mM glycolic acid alsoincreased the decolorization rate significantly; the highest decoloring rate reachedto87.6%on the10thday after the addition of1mM oxalate, which was6.1%higherthan the control.0.05%,0.1%and0.15%Tween80increased the decolorization rateof direct sky blue5B significantly, and0.1%Tween8had the best effect and itspeak rate was97.0%, which was14.4%higher than the control.3. The effects of three yeasts （Candida utilis, Saccharomyces cerevisia and C.tropicalis） and P. ostreatus inocula which were precultured in the medium whichcontain different concentrations of direct sky blue5B （50mg/L,100mg/L,200mg/L,300mg/L,400mg/L） respectively on the activity of ligninolytic enzymeand the decolorization rate of direct sky blue5B under the single-strainfermentation of P. ostreatus in liquid-state rice straw media were studied. The resultshowed that C. utilis and S. cerevisiae both increased significantly the activity ofLac, C. utilis had the best effect, and the activity was630U/L, which was1.56times of the control; three kinds of yeast all increased the activity of MnPsignificantly, C. utilis was the best of them and its peak activity was380U/L,which was177U/L higher than the control. Compared to the control, the inoculawhich was precultured in the50mg/L to200mg/L direct sky blue5B increased theactivity of Lac, the highest Lac activity obtained when the inoculum wasprecultured in50mg/L dye and it reached to616U/L on8thday, which was165U/L higher than the control; the inoculum precultured in100mg/L dye increasedthe activity of MnP and it reached330U/L, which was77U/L higher than thecontrol.Compared to the fermentation system of without adding yeast strain, C. utilis,S. cerevisiae and C. tropicalis all promoted significantly the decoloring effectrespectively and their highest decolorization rates were all more than90%. Thedecoloring effect was the best when C. utilis was vaccinated and its highest ratereached to96.3%, which was14.2%higher than the control. Compared to thecontrol, the inocula which were precultured in50mg/L to100mg/L direct sky blue 5B increased the decolorization rate obviously, and the inoculum which wasprecultured in50mg/L dye had the best effect and their highest decolorization ratewas90%, which was9.5%higher than the control; however, the inoculum whichwas precultured in300mg/L and400mg/L dye decreased the decolorization rate ofdirect sky blue5B remarkably. Through the comparion of the relationship betweenthe activity of ligninolytic enzyme system and the decolorization rate of dye, wecan conclude that the correlation between the activity of Lac and MnP and thedecolorization rate of direct sky blue5B was a certain relationship.4. According to the above experimental results, the metal ions, the organicacid, the tween80and the yeasts were all used as the design elements of orthogonalexperiment. Orthogonal experiment results showed that the optimal experimentalcondition for the best decolorization rate of direct sky blue5B was:0.5mM Cu²⁺,1mM glycollate acid sodium,0.05%tween80and C. utilis were added into the P.ostreatus fermentation system of liquid-state rice straw medium. The effect weightof each factor was: tween80> the yeast> the metal ions> the organic acid. Thedecolorization rate of direct sky blue5B dye was98.2%under this optimal culturecondition.