焦化污染场地中萘降解菌的分离及降解特性

Degradation of naphthalene by degrading bacteria isolated from coking contaminated sites

为从焦化污染场地中分离萘高效降解菌,采用萘作为唯一碳源,通过梯度筛选和富集培养获得一株高效萘降解菌株AO-4。依据形态及16S rDNA基因序列,将其鉴定为铜绿假单胞菌(Pseudomonas aeruginosa)。通过PCR验证了菌株基因组中含有萘双加氧酶基因(nahAC)和邻苯二酚2,3-双加氧酶基因(nahH),推测该菌可能是通过水杨酸途径对萘进行降解。在对菌株降解特性分析中发现,菌株AO-4在24h对萘(400mg/L)的降解率达到97.67%,菌株的生长、脱氢酶活性与萘的降解率呈正相关。其次,探究了温度、pH、萘初始浓度和菌量对菌株降解萘的影响,明确最适降解温度为30℃、pH为5.0~7.0;在一定范围内,菌株降解效率随着萘浓度和菌量的增大而提高。对该菌株降解多环芳烃(PAHs)的广谱性测试表明,AO-4不仅能有效降解萘,而且对其他PAHs,如芴、菲、蒽和芘在单一和混合体系中均有不同程度的降解,研究结果可为PAHS污染场地的微生物修复提供一定的技术支持。

To isolate high effective naphthalene degradation bacteria,a strain AO-4,which could use naphthalene as the sole carbon source by gradient screening and enrichment culture,was obtained from the coking contaminated soil.According to the morphology and 16S rDNA gene sequence,it was identified as Pseudomonas aeruginosa.It was verified by PCR that the strain had naphthalene dioxygenase gene(nahAC)and catechol 2,3-dioxygenase gene(nahH),so the possible degradation pathway of naphthalene might be salicylic acid pathway.In the analysis of the degradation characteristics of the strain,it was found that the degradation rate of naphthalene(400mg/L)by strain AO-4 reached 97.67%in 24h.During the degradation process,the growth and dehydrogenase activity of the bacteria were positively correlated with the degradation rate of naphthalene.The effects of temperature,pH,initial naphthalene concentration and bacterial population on the degradation of naphthalene by the strain were explored.The results showed that the optimum degradation temperature was 30℃and pH was 5.0-7.0.Within a certain range,the degradation efficiency of the strain increased with the increase of naphthalene concentration and bacterial population.The broad-spectra property experiments of PAHs degradation showed that strain AO-4 could not only degrade naphthalene effectively,but also could degrade other PAHs fluorene,phenanthrene,anthracene and pyrene in single and mixed systems.The above research results can provide technical support for the bioremediation of PAHs-contaminated sites.