16S rDNA-RFLP分析六氯苯好氧降解菌群的结构及其多样性

从某化工厂排水沟底泥中取样,经2个月的富集驯化得到六氯苯好氧降解菌群。通过测定该微生物菌群在降解六氯苯过程中累积耗氧量、微生物生长曲线及Cl-浓度的变化,证明在好氧条件下该微生物菌群能够以六氯苯为唯一碳源和能源生长。当培养温度为30℃,pH为7.0时,该菌群能在18d内将无机盐培养基中浓度为4.5mg/L的六氯苯降解55%以上,降解速率达到137.5μg/(L.d)。对降解菌群提取总DNA,选择性扩增细菌16S rDNA片段,建立克隆文库。通过限制性内切酶(限制性内切酶HaeⅢ和RsaⅠ)分析,得到9种不同的谱型,其中3种谱型是主要谱型。对主要谱型的克隆子测序,结果表明,它们分别与Alcaligenes和Azospirillum菌属相似性最高。该菌群在去除环境中难降解的有机氯污染物方面具有应用前景。

16S rDNA-RFLP analysis of structure and diversity of an aerobic microbial community degrading hexachlorobenzene

Hexachlorobenzene is a chlorinated aromatic hydrocarbon that was widely used as a seed dressing for prevention of fungal growth on crops, and is also a component of fireworks, ammunition, and synthetic rubbers. Because of the bioaccumulation and persistence of hexachlorobenzene as well as its potential toxicity, hexachlorobenzene must be removed from environment. The potential for aerobic dechlorination of hexachlorobenzene by a hexachlorobenzene-adapted mixed culture was investigated. An aerobic microbial community which was able to grow at the presence of hexachlorobenzene was enriched from sediment from contaminated site after incubating about 2 months. During the growth of the mixed microorganisms on hexachlorobenzene, the accumulating consumption of oxygen, the microbial population curve and the release of Cl- were investigated. The data suggest the rapid degradation of hexachlorobenzene to support microbial growth and the aerobic decholrination of hexachlorobenzene was observed. The result showed that the mixed microorganisms were able to utilize hexachlorobenzene as sole carbon and energy source. It was shown that up to 55% of HCB could be degraded during 18 days incubation at 30 degrees C in mineral salts medium (pH 7.0) with 4.5mg/L HCB. The calculated rate of hexachlorobenzene biodegradation was 137.5 microg/ (L x d). The 16S rDNA genes were amplified from community DNA by using primers specific to bacteria and were subsequently cloned. The cloned 16S rDNA fragments were reamplified, and restriction analysis was performed following separate digestion with enzymes Hae III and Rsa I. Application of restriction fragment length polymorphism screening approach revealed 9 clusters, and 3 major clusters were sequenced. Nearly complete 16S rDNA sequence analysis show that the microbial community was dominated by Alcaligenes and Azospirillum groups. This is the first report describing aerobic dechlorination of hexachlorobenzene via dehalorespiration by a microbial community which was enriched from contaminated site. The microbial community can be used to degrade highly recalcitrant chlorinated pollutants.