高效烃降解菌群的驯化、降解特性及初步应用

High-effective Hydrocarbon-degrading Bacteria:Domestication,Degradation Characteristics and Preliminary Application

微生物技术在石油污染土壤的修复中具有广阔的应用前景,而获得具有高降解效率的菌(菌群)是保证高效修复的关键。该研究从4种不同含油土壤中驯化、培养获得稳定、高效降解石油烃的1号菌群,对其进行高通量测序,确定菌群组成;研究不同环境因素对该菌群石油烃降解能力的影响,确定了最佳降解条件;对菌群降解石油烃的特性和降解动力学进行了分析;探究了该菌群在较高浓度含油土壤中的应用潜力,以及以破碎荞麦壳为载体,将菌群固定化后修复石油烃-镉复合污染土壤的能力。结果表明,该菌群主要由寡养单胞菌属(Stenotrophomonas)、假单胞菌属(Pseudomonas)、苍白杆菌属(Ochrobactrum)、乳杆菌属(Lactobacillus)和无色杆菌属(Achromobacter)等组成;在原油质量浓度为0.5%,p H为8,盐度为1%,温度为35℃,C∶N∶P为100∶2∶1,以硝酸铵为氮源的最佳条件下,培养10 d后,菌群对石油的降解率由52.1%提高至76.6%;GC-MS分析结果显示,培养9 d和24 d后菌群对C13~C26烷烃平均降解率分别为90.3%和97%,说明该菌群能够快速高效降解中长链烷烃。菌群对原油初始浓度为0.5%和4%的降解符合一级反应动力学模型。将菌群接种于石油含量为4 631 mg/kg、8 591 mg/kg的土壤中,40 d后降解率分别为47.7%、26.4%;固定化后的菌群用于修复石油烃-镉复合污染土壤,石油烃降解率、土壤脱氢酶活性和过氧化氢酶活性高于其他组,可交换态镉的浓度低于其他组。以上结果充分显示了该菌群在石油浓度较高的土壤以及石油烃-镉复合污染土壤修复中的应用潜力。

Microbial technology is of a broad application prospect in the remediation of oil-contaminated soil,and obtaining the bacteria(microbial communities)of high degradation efficiency is the key to ensuring efficient remediation.In this study a microbial consortium(named No.1)with stable and efficient capacity of degrading petroleum hydrocarbons was do-mesticated from four different kind of oil-contaminated soil,and the high-throughput sequencing was conducted to de-termine the composition of the consortium;the effects of different environmental factors on the petroleum hydrocarbon degradation capacity of the No.1 consortium were investigated,and the optimal degradation condition was determined;fur-thermore,the degradation characteristics and kinetics were analyzed,and the potential application of the No.1 consortium to the soil heavily polluted by oil was explored,which involved the consortium being immobilized on broken buckwheat husks and then was used to remediate the combined soil pollution of petroleum hydrocarbon and cadmium.Consequently,the study showed that the No.1 consortium was mainly composed of Stenotrophomonas,Pseudomonas,Ochrobactrum,Lactoba-cillus and Achromobacter,and after 10 days cultivation,as crude oil concentration in the polluted soil sample was 0.5%,and under the optimal condition:1%salinity,pH of 8,temperature of 35℃,C∶N∶P as 100∶2∶1,and ammonium nitrate being as the nitrogen source,the degradation rate of the consortium increased from 52.1%to 76.6%;the results of GC-MS analysis showed that the average degradation rates of C13~C26 alkanes by the consortium were 90.3%and 97%after 9 and 24 days of cultivation,respectively,indicating that the medium and long-chain alkanes were rapidly and efficiently degraded;and the degradation of crude oil by the consortium fit the first-order kinetics when the initial concentrations were 0.5%and 4%.In addition,when the consortium was inoculated into polluted soil with initial petroleum hydrocarbon content of 4631 mg/kg and 8591 mg/kg,after 40 days it was found the degradation rates were respectively 47.7%and 26.4%.The immobilized con-sortium applied to the remediation of combined hydrocarbon/cadmium polluted soil was better than others(without being im-mobilized)in terms of degradation rate of petroleum hydrocarbon,soil dehydrogenase activity,and catalase activity,but the concentration of exchangeable cadmium was lower.The results obtained so far from the experimental study demonstrate the potential application of the microbial consortium to the remediation of heavy oil-polluted soil and soil contaminated by petro-leum hydrocarbon and cadmium.