Cd胁迫下油菜土壤微生物区系及主要生理类群研究

Effect of Cd on Soil Microbial Populations and Major Microbial Physiological Groups in Oilseed rape Soil

在实验室条件下,用传统的微生物培养法,研究了不同浓度的外源重金属Cd对油菜土壤微生物区系及主要生理类群的影响。结果表明,Cd对油菜土壤微生物的影响随微生物区系或生理类群、培养时间和Cd浓度的不同而不同。前期Cd对好氧细菌有刺激作用,后期有抑制作用;浓度为0.5和5.0mg.kg-1的Cd对放线菌没有影响,浓度为1.0和3.0mg.kg-1的Cd对放线菌有刺激作用,浓度为10mg.kg-1的Cd对放线菌有抑制作用;Cd对真菌的影响比对好氧细菌和放线菌的影响要小得多;Cd对自生固氮菌和反硝化细菌主要表现为刺激作用;Cd对纤维素分解菌、氨化细菌、硝化细菌的作用随培养时间、Cd浓度的不同分别表现出不影响、刺激和抑制。总体来讲,Cd对各微生物指标表现出随浓度的变化没有连续性。油菜土壤的硝化细菌可以有效地表征油菜土壤Cd污染的程度和Cd污染时间的长短;油菜土壤反硝化细菌可以反映Cd浓度在3～10mg.kg-1之间污染的程度。本研究反映了油菜土壤的重金属Cd污染的生态特征。

Under laboratory conditions, with traditional cultivation method, effect of Cd at different concentrations on microbial populations and major microbial physiological groups in cole soil were studied.The results showed that in the early stage when the soils were incubated, the bacteria were promoted by Cd, however, it was inhibited in the later stage. 0.5 mg·kg^-1 Cd and 5.0 mg·kg^-1 Cd had no effect on the aetinomyeetes, while 1.0 mg·kg^-1 or 3.0 mg·kg^-1 Cd could stimulate the aetinomyeetes quickly, 10 mg·kg^-1 Cd could inhibit actinomycetes. The effect of Cd on the fungi was not obvious. Bacteria and actinomyeetes in the soil were more sensitive to Cd than fungi. The azotobacteria were stimulated by Cd, so were the denitrobaeteria. The effects of Cd on the cellulose decomposing bacteria, the ammonifying bacteria and the nitrobaeteria varied with the culture-time and concentrations of Cd, On the whole, the effects of Cd on all the soil microbial populations and the major microbial physiological groups were not continuous alongside the continuous variation of concentrations of Cd. The nitrobaeteria could be used as an indicator of Cd pollution degree and Cd pollution time in the cole soil. Denitrobaeteria could indicate the pollution degree of Cd in soil with 3-10 mg·kg^-1 Cd. These presented the ecological characteristics in cole soil contaminated by Cd.