氯酚污染土壤的生物强化修复及其微生物种群动态变化的分子生物学监测

Bioremediation of chlorophenol-contaminated soil using bioaugmentation technology and the soil microbial population dynamics

在氯酚污染的土壤中接种氯酚降解菌,研究了受污染土壤的生物强化修复.利用传统的微生物计数方法和现代分子生物学手段,研究了生物强化修复过程中微生物种群的动态变化情况.在受氯酚污染的土壤样品中,以氯酚为唯一碳源和能源,分离出了多株对氯酚具有较高降解能力的微生物,利用16S rDNA序列分析方法对部分微生物进行了种属鉴定.土壤中存在的土著的氯酚降解菌可以对低含量的氯酚(100mg·g-1)进行降解;但是当土壤中氯酚含量较高(500mg·g-1)时,土著微生物的降解能力受到限制,这可能是高浓度的氯酚对土著的氯酚降解菌会产生毒性作用.接种外来微生物后,土壤中可以培养的氯酚降解菌的总数从开始的106CFU·g-1增加到108CFU·g-1,并且,在氯酚含量为100mg·g-1的土壤样品中,微生物数目的增加比在氯酚含量为500mg·g-1土壤样品中更快.这表明接种的外来微生物可以在土壤中很好地生长繁殖,有效地促进土壤中氯酚的生物降解.接种外来微生物可以减轻土壤中氯酚对土著微生物初期产生的不利影响.土壤中的氯酚可能会改变微生物种群结构.DGGE分析结果表明,在未受氯酚污染和受氯酚污染的土壤样品中,存在一些共同的DNA谱带,但谱带强度有明显的差异.在受污染的土壤中接种外来微生物进行生物强化,可以促进污染物的生物降解过程,是生物修复过程中的一种重要手段,有着广泛的应用前景,将在我国受污染环境的生物修复中发挥重要作用.

The bioremediation of＇chlorophenol-contaminated soil was investigated following bioaugmentation with chlorophcnol-degrading bacterial culture. The changes in soil microbial population dynamics was evaluated using traditional enumeration method and the modem molecular biological method. Several strains capable of degrading chlorophenol was isolated from contaminated soil using chlorophenol as sole carbon source, some of them were identified based on 16S ribosomal-DNA sequences. The indigenous microorganisms existed in the contaminated soil could degrade low concentration of chlomphenol （ 〈 100 mg·g^-1） , however, their degradative capacity was limited when chlorophenol concentration was high （about 500 mg·g^-1 ） , which may be caused by the toxic effect of high concentration of chlorophenol on the indigenous bacteria. And the culturablc bacterial degraders were increased from 106CFU·g^-1 soil to 108 CFU·g^-1 soil after inoculating with the degrader. Moreover, the bacterial population increased faster in 100 mg·g^-1 microcosoms than in 500 mg·g^-1 microcosoms, revealing that the inoculated bacteria could survive and enhance the biodegradation of chlorophenol in contaminated soil. The inoculation with ehlorophenol degrader Rhodococcus sp. could reduce the negative effect of chlorophenol on cuhurable bacterial numbers in soil. The chlorephenol added in soll could change the soll microbial population structure. The results of DGGE indicated that there are some common DNA strands in both uncontaminated and contaminated soils, but there existed difference in strand strength, The results suggested that bioaugmentatlon may be beneficial for the remediation of chlorophenol-contamlnated soil not only by increasing the rate of pollutant degradation but also by decreasing the negative effects of pollutant on the indigenous soll microorganisms. Therefore bioaugmentatlon is an affeetive approach for bioremediation and will play more and more important role in the filed of bioremediation of contaminated environment.