| More than 500,000 urban sites in China have been contaminated to varying degrees.Pollution by polycyclic aromatic hydrocarbons（PAHs）and total petroleum hydrocarbons（TPH）is particularly prevalent,and is mainly based on low and medium concentration organic compound pollution.It is difficult to remediate.Microorganisms and their enzymes remediation technology is less environmental disturbance,green and safe,and more suitable for in situ remediation of low and medium concentration contaminated soil.However,microbial growth is easily restricted by soil environment and pollutant concentration.It is difficult to colonize the soil.Free enzymes are easily inactivated,resulting in high remediation costs.To address the above problems,based on the existing research of the group,this study selected Trametes versicolor,white rot fungi with broad-spectrum degradation characteristics,and investigated the physiological characteristics of Trametes versicolor and the degradation effect of pollutants in the PAHs-TPH compound pollution environment.The degradation ability of cellulose-based calcium alginate hydrogel microspheres immobilized enzymes on PAHs and TPH was investigated.Trametes versicolor prepared fungal agents and immobilized enzymes were applied to PAHs-TPH compound contaminated soil to provide technical support for the engineering application of white rot fungal agents/immobilized enzymes in actual industrial contaminated sites.The specific results are as follows:（1）Trametes versicolor degraded 88.08%of single benzo（a）pyrene（Ba P）in 7 days.The degradation rate of Ba P was 69.25%,which decreased by 18.83%under Ba P-TPH pollution conditions.The degradation rate of TPH under compound pollution conditions was 16.95%.In addition,Ba P degradation showed significant negative and positive correlations with extracellular protein concentration and laccase activity,respectively.And TPH degradation was significantly and positively correlated with intracellular protein concentration.The degradation effect of Trametes versicolor on Ba P and TPH was closely related to the expression of extracellular and intracellular proteins.The presence of TPH increased the degree of cellular oxidative damage,inhibited laccase secretion,and protein expression leading to the inhibition of Ba P degradation.（2）Cellulose-based hydrogel microspheres were obtained using degradable cellulose and sodium alginate preparation.It can be rapidly sequestered with extracellular crude enzyme of Trametes versicolor by physical adsorption.The mediator 1-hydroxybenzotriazole（HBT）,biosurfactants NK-BSoil-2 and NK-BSoil-3 improved the oxidation and bioavailability of Ba P and significantly promoted the degradation of Ba P by immobilized enzyme.Tween 80,NK-BSoil-1,Cu2+decreased the binding site of Ba P to immobilized enzyme and inhibited the degradation of Ba P by immobilized enzyme.The immobilized enzyme degraded 89.02%of Ba P in 24 h under the condition of Ba P-TPH compound pollution.The immobilized enzyme had prominent effect on Ba P degradation,and the extracellular enzyme had poor correlation with TPH degradation and no significant degradation effect on TPH in a short time.（3）The remediation ability of solid-state fermentation agent was better than liquid and unfermented solid-state agents for 60 days,and the degradation rate of Ba P and TPH in the compound contaminated soil was up to 56.16%and 15.73%.The optimal conditions for remediation of Ba P contaminated soil by immobilized enzymes were HBT 0.03 m M,NK-BSoil-3 9 mg/g soil and 0.5 g/g soil of immobilized enzymes.The degradation rates of phenanthrene,pyrene and Ba P in the composite contaminated soil by immobilized enzymes showed that Ba P（82.55%）>pyrene（27.2%）>phenanthrene（17.55%）within 96 h.The molecular structure of Ba P was more easily bound to the enzyme molecules for degradation.Solid-state fermentation agent is more easily adapted to compound soil environment and has excellent remediation effect.The immobilized enzyme protects the enzyme molecule from inactivation.Immobilized enzymes can continuously play a degrading role in the soil and have good degradation effect on PAHs. |
