高分子量多环芳烃降解菌筛选及在土壤电动-生物修复中应用

采用富集培养和多环芳烃双加氧酶基因检测方法,从焦化场地多环芳烃污染土壤分离筛选出9株PAHs降解菌。以高分子量多环芳烃芘为唯一碳源进行摇瓶降解实验,结果表明,J6、S5、S4、S2和B4对芘具有较好的降解能力,21 d时芘降解率均达55%以上,其中B4处理芘的降解率最高,达到70.2%。进一步研究了该5株菌及其混合菌对土壤中芘的降解效果,发现混合菌的降解效果高于单菌的降解效果,其中混合菌H4和单菌B4的降解效果较好,49 d时混合菌H4和单菌B4处理土壤中芘的降解率达29.3%和18.3%。经过16S rRNA基因序列比对,鉴定J6菌株为赤红球菌(Rhodococcus ruber),S5为芽孢杆菌属(Bacillus sp.),S4和S2是鞘脂单胞菌属(Sphingopyxis sp.),B4为假单胞菌属(Pseudomonas sp.)。在电场条件下,混合菌H4和单菌B4处理微生物数量及活性均显著提高,芘的降解率较单独H4和B4处理提高33.0%和20.1%,说明筛选出的5株高分子量多环芳烃降解菌具有较强的电场适应能力,可在高分子量多环芳烃污染土壤电动-微生物修复中应用。     

一株高效降解芘的细菌分离、鉴定及其降解效果

摘要：【目的】获得高效降解高分子量多环芳烃的细菌,并研究其对多环芳烃的降解能力。【方法】利用富集培养和芘升华平板方法,从焦化厂污染土壤中分离多环芳烃降解细菌,对分离菌株通过形态特征、16S rRNA基因和gyrb基因序列相似性分析进行鉴定,并研究该菌对高分子量多环芳烃（HMW-PAHs）的降解效果。【结果】筛选到一株能以芘、苯并蒽、屈、苯并芘、茚并芘、苯并苝、荧恩为碳源和能源生长并降解这些底物的菌株HBS1,该菌株的16S rRNA基因和gyrb基因序列与Gordonia amicalis的相应基因的相似     

一株高浓度多环芳烃降解菌的鉴定和降解特性

采用选择性富集培养方法,从沈抚灌区土壤中分离得到多环芳烃(PAHs)高效降解菌NI2,应用此降解菌制备固定化菌剂,修复焦化厂内高浓度PAHs污染土壤,并通过生理生化和16S rDNA测序进行微生物鉴定.经过30 d的降解实验,菌N12对污染土壤中各PAH的去除率＞66％,总去除率为80％.生理生化和16S rDNA测序分析表明,分离得到的菌株N12为分支杆菌属(Mycobacterium sp.),该菌具有与其他分枝杆菌同源的双加氧酶基因nidA和pdoA2.结果表明,从土壤中筛选获得的分枝杆菌可以修复高浓度PAHs污染工业土壤.     

污染土壤中苯并(a)芘的微生物降解途径研究进展

苯并(a)芘(BaP)是一种具有强致癌、致畸和致突变的多环芳烃(PAHs)。为了修复BaP污染的土壤,探索其降解途径是很重要的。为此,综述了国内外有关污染土壤中苯并(a)芘的微生物降解情况,对不同真菌、细菌降解苯并(a)芘的能力、代谢途径、共代谢底物以及环境影响因素进行了介绍和比较,提出了苯并(a)芘中间代谢产物的累积及其环境毒性方面的研究是修复苯并(a)芘污染土壤的重要方向。     

分枝杆菌TZh51菌株的分离鉴定及其生物修复污染土壤的特性

[目的]为获得降解芘的微生物菌株,并用其生物修复被多环芳烃污染的土壤.[方法]芘降解菌的分离采用平板升华法.根据表型观察、生理生化特性和16S rDNA的序列同源性分析,对菌株进行分类学鉴定.通过活菌计数、HPLC测定多环芳烃的残留量,研究菌株在固体、液体无机盐培养基以及在污染土壤中降解多环芳烃(polycyclic aromatic hydrocarbons,PAHs)的能力.[结果]分离到4株能降解芘的菌株TZh51、TZh52、TG42和TG52.实验结果表明,TZh51降解PAHs的能力强于其余3株菌.TZh51被鉴定为分枝杆菌属(Mycobacterium sp.),但与已发表的分枝杆菌菌株M11为不同的种.TZh51接种在芘膜的固体无机盐培养基上,测定获得最大芘降解量的条件是培养温度为3512和芘膜厚度为130 ng/mm2.在芘浓度为50、100 mg/L的液体无机盐培养基中培养,6天时TZh51的芘降解率分别达到91.9%、71.8%,10天时菌体数量分别达到最大值为2.0、6.0×108cfu/mL;TZh51降解芘的效果强于M11.在种植作物的处理中,到第6周时TZh51的菌体数量达到每克干土含7.2×108个菌落数,到第8周时菲、荧蒽和芘的降解率分别达到91.4%、86.9%和85.8%;[结论]TZh51具有很强降解PAHs的能力;另外,TZh51与作物联合生物修复污染土壤的效果明显.     

深海多环芳烃降解菌新鞘氨醇杆菌H25的降解特性及降解基因

[目的]为了从深海环境中筛选新的多环芳烃降解菌,了解其降解基因及降解特性.[方法]以原油作为碳源从印度洋深海海水样品中富集筛选出降解能力较强的多环芳烃降解菌,并根据已报道的相关菌属的多环芳烃起始双加氧酶大亚基序列及侧翼序列设计兼并引物进行扩增.[结果]获得了1株能够高效降解原油、柴油及多种多环芳烃的菌株H25.经16S rDNA序列系统发育分析表明它属于新鞘氨醇杆菌属(Novosphingobium)(96%).并从该菌株中扩增获得2条相似度为91.0%双加氧酶基因片段.2条序列在NCBI上Blastn分析表明均与菌株N.aromaticivorans DSM12444T的降解质粒pNL1上的双加氧酶大亚基具有最高相似度,分别为99.6%和91.0%.根据pNL1上的双加氧酶序列设计引物获得了包含H25双加氧酶大亚基及上下游序列的2个基因片段H25 Ⅰ(2.9kb)和H25Ⅱ(4.5kb).另外,单碳降解实验表明H25对联苯、2-甲基萘、2,6-二甲基萘、菲、二苯并噻吩、二苯并呋喃等均有较好的降解能力.[结论]H25菌株是Novosphingobium属可能的新种.深海细菌在大洋环境多环芳烃污染的自然净化中起到一定作用,并在环境生物修复中有较大的应用前景.     

一株芘降解菌的分离鉴定及其降解效果

以芘为唯一碳源,采用平板升华法,从徐州市卧牛山焦化厂周围污染土壤中分离得到一株芘降解菌SE12.经形态观察、生理生化试验和16S rDNA鉴定,该菌株属于分枝杆菌属(Mycobacterium sp.)菌株,与快速生长型非致病性南非分枝杆菌(M.austroa fricanum ATCC33464)的同源性达到98%.SE12降解芘的最适pH和温度为pH9和30℃.当土壤芘初始含量为100和200mg.kg-1,SE12接种量为107CFU.g-1时,30℃培养28d后土壤芘降解率分别达到97%和99%.利用双加氧酶基因的同源序列引物nidAF/nidAR和nidBF/nidBR进行扩增,得出了该菌株编码双加氧酶大亚基和小亚基的基因片段,它们与已知降解芘的分枝杆菌的双加氧酶基因具有高度同源性.     

黑麦草根系分泌物剂量对污染土壤芘降解和土壤微生物的影响

模拟根际根系分泌物梯度递减效应,研究了黑麦草根系分泌物剂量对污染土壤中芘降解特征和土壤微生物生态特征的影响.结果表明:污染土壤中芘残留量随根系分泌物添加剂量的增加呈现先下降后上升的非线性变化,达到最低芘残留量的添加剂量是总有机碳(TOC) 32.75 mg·kg-1,说明此浓度下根系分泌物显著促进了芘的降解;土壤微生物生物量碳和微生物熵的变化趋势与污染土壤中芘残留量变化趋势相反,表明土壤微生物与污染土壤 中芘残留量存在密切关系.芘污染土壤中微生物群落以细菌占主导地位,且细菌变化趋势与芘降解变化一致,表明芘以细菌降解为主,根系分泌物主要通过影响细菌数量,进而影响芘的降解.能催化有机物质脱氢反应的土壤微生物胞内酶——脱氢酶活性的变化与土壤微生物变化趋势一致,进一步证明微生物及其生物化学特性变化是污染土壤中芘残留量随根系分泌物添加剂量变化的生态机制.     

嗜麦芽寡养单胞菌PX1的降解芘特性及定殖效能

为丰富多环芳烃降解菌菌种库、降低农作物的污染风险,本研究对一株可高效降解多环芳烃(PAHs)的植物内生菌进行筛选鉴定,并初步探究其降解途径以及定殖效能。结果表明: 菌株PX1为嗜麦芽寡养单胞菌。该菌株对多环芳烃的降解具有广谱性,7 d几乎可彻底降解PAH无机盐培养基中的萘,在分别含有50.0 mg·L^-1菲、20.0 mg·L^-1芘、20.0 mg·L^-1荧蒽和10.0 mg·L^-1苯并[a]芘的培养体系中,对菲、芘、荧蒽、苯并[a]芘的降解率分别为72.6%、50.7%、31.9%和12.9%。选取芘作为PAHs模型研究菌株PX1的降解特性。酶活性试验表明,芘可诱导菌株PX1体内邻苯二甲酸双加氧酶、邻苯二酚-1,2-双加氧酶和邻苯二酚-2,3-双加氧酶的活性。在芘降解过程中检测到4,5-环氧化芘、4,5-二羟基芘、龙胆酸/原茶儿酸、水杨酸、顺-己二烯二酸/2-羟粘糠酸半醛、顺-2′-羧基苯丙酮酸、1-羟基-2-萘甲酸、水杨醛等中间产物。浸种定殖试验表明,菌株PX1可高效定殖到空心菜和小麦体内,显著促进空心菜和小麦生长,并能够将空心菜、小麦体内及其生长基质中的芘浓度分别降低29.8%～50.7%、52.4%～67.1%和8.0%～15.3%。表明菌株PX1主要通过“水杨酸途径”和“邻苯二甲酸途径”降解芘,且可以定殖到植物体内,促进植物生长。     

一株高分子量多环芳烃降解菌的筛选、鉴定及降解特性研究

采用富集培养方法从多环芳烃污染土壤中筛选分离得到1株能以苯并[a]芘(B[a]P)为唯一碳源和能源生长的菌株.形态特征观察和16S rDNA序列分析结果表明,该菌株为副球菌属(Paracoccus sp.),编号为HPD-2.HPD-2在3.0 mg/L的B[a]P液体培养基中生长较慢,培养5 d后B[a]P的降解率为89.7%.同时,该菌株对四环的芘和荧蒽也具有较好的降解能力,培养7 d后芘和荧蒽的降解率分别达到47.2%和84.5%.可见,该菌株对高分子量PAHs具有很好的降解潜力.     

Bacterial Diversity of a Consortium Degrading High-Molecular-Weight Polycyclic Aromatic Hydrocarbons in a Two-Liquid Phase Biosystem

High-molecular-weight (HMW) polycyclic aromatic hydrocarbons (PAHs) are pollutants that persist in the environment due to their low solubility in water and their sequestration by soil and sediments. Although several PAH-degrading bacterial species have been isolated, it is not expected that a single isolate would exhibit the ability to degrade completely all PAHs. A consortium composed of different microorganisms can better achieve this. Two-liquid phase (TLP) culture systems have been developed to increase the bioavailability of poorly soluble substrates for uptake and biodegradation by microorganisms. By combining a silicone oil–water TLP system with a microbial consortium capable of degrading HMW PAHs, we previously developed a highly efficient PAH-degrading system. In this report, we characterized the bacterial diversity of the consortium with a combination of culture-dependent and culture-independent methods. Polymerase chain reaction (PCR) of part of the 16S ribosomal RNA gene (rDNA) sequences combined with denaturing gradient gel electrophoresis was used to monitor the bacterial population changes during PAH degradation of the consortium when pyrene, chrysene, and benzo[a]pyrene were provided together or separately in the TLP cultures. No substantial changes in bacterial profiles occurred during biodegradation of pyrene and chrysene in these cultures. However, the addition of the low-molecular-weight PAHs phenanthrene or naphthalene in the system favored one bacterial species related to Sphingobium yanoikuyae. Eleven bacterial strains were isolated from the consortium but, interestingly, only one—IAFILS9 affiliated to Novosphingobium pentaromativorans—was capable of growing on pyrene and chrysene as sole source of carbon. A 16S rDNA library was derived from the consortium to identify noncultured bacteria. Among 86 clones screened, 20 were affiliated to different bacterial species–genera. Only three strains were represented in the screened clones. Eighty-five percent of clones and strains were affiliated to Alphaproteobacteria and Betaproteobacteria; among them, several were affiliated to bacterial species known for their PAH degradation activities such as those belonging to the Sphingomonadaceae. Finally, three genes involved in the degradation of aromatic molecules were detected in the consortium and two in IAFILS9. This study provides information on the bacterial composition of a HWM PAH-degrading consortium and its dynamics in a TLP biosystem during PAH degradation.     

Physiological characterization of Mycobacterium sp. strain 1B isolated from a bacterial culture able to degrade high-molecular-weight polycyclic aromatic hydrocarbons

AIM: The aim of this study was to further characterize a bacterial culture (VUN 10,010) capable of benzo[a]pyrene cometabolism. METHODS AND RESULTS: The bacterial culture, previously characterized as a pure culture of Stenotrophomonas maltophilia (VUN 10,010), was found to also contain another bacterial species (Mycobacterium sp. strain 1B), capable of degrading a similar range of PAH substrates. Analysis of its 16S rRNA gene sequence and growth characteristics revealed the strain to be a fast-growing Mycobacterium sp., closely related to other previously isolated PAH and xenobiotic-degrading mycobacterial strains. Comparison of the PAH-degrading characteristics of Mycobacterium sp. strain 1B with those of S. maltophilia indicated some similarities (ability to degrade phenanthrene and pyrene), but some differences were also noted (S. maltophilia able to degrade fluorene, but not fluoranthene, whereas Mycobacterium sp. strain 1B can degrade fluoranthene, but not fluorene). Unlike the S. maltophilia culture, there was no evidence of benzo[a]pyrene degradation by Mycobacterium sp. strain 1B, even in the presence of other PAHs (ie pyrene) as co-metabolic substrates. Growth of Mycobacterium sp. strain 1B on other organic carbon sources was also limited compared with the S. maltophilia culture. CONCLUSIONS: This study isolated a Mycobacterium strain from a bacterial culture capable of benzo[a]pyrene cometabolism. The Mycobacterium strain displays different PAH-degrading characteristics to those described previously for the PAH-degrading bacterial culture. It is unclear what role the two bacterial strains play in benzo[a]pyrene cometabolism, as the Mycobacterium strain does not appear to have endogenous benzo[a]pyrene degrading ability. SIGNIFICANCE AND IMPACT OF THE STUDY: This study describes the isolation and characterization of a novel PAH-degrading Mycobacterium strain from a PAH-degrading culture. Further studies utilizing this strain alone, and in combination with other members of the consortium, will provide insight into the diverse roles different bacteria may play in PAH degradation in mixed cultures and in the environment.     

Microbial Dioxygenase Gene Population Shifts during Polycyclic Aromatic Hydrocarbon Biodegradation

The degradation of polycyclic aromatic hydrocarbons (PAHs) by bacteria has been widely studied. While many pure cultures have been isolated and characterized for their ability to grow on PAHs, limited information is available on the diversity of microbes involved in PAH degradation in the environment. We have designed generic PCR primers targeting the gene fragment encoding the Rieske iron sulfur center common to all PAH dioxygenase enzymes. These Rieske primers were employed to track dioxygenase gene population shifts in soil enrichment cultures following exposure to naphthalene, phenanthrene, or pyrene. PAH degradation was monitored by gas chromatograph with flame ionization detection. DNA was extracted from the enrichment cultures following PAH degradation. 16S rRNA and Rieske gene fragments were PCR amplified from DNA extracted from each enrichment culture and an unamended treatment. The PCR products were cloned and sequenced. Molecular monitoring of the enrichment cultures before and after PAH degradation using denaturing gradient gel electrophoresis and 16S rRNA gene libraries suggests that specific phylotypes of bacteria were associated with the degradation of each PAH. Sequencing of the cloned Rieske gene fragments showed that different suites of genes were present in soil microbe populations under each enrichment culture condition. Many of the Rieske gene fragment sequences fell into clades which are distinct from the reference dioxygenase gene sequences used to design the PCR primers. The ability to profile not only the bacterial community but also the dioxygenases which they encode provides a powerful tool for both assessing bioremediation potential in the environment and for the discovery of novel dioxygenase genes.     

Microbial dioxygenase gene population shifts during polycyclic aromatic hydrocarbon biodegradation

The degradation of polycyclic aromatic hydrocarbons (PAHs) by bacteria has been widely studied. While many pure cultures have been isolated and characterized for their ability to grow on PAHs, limited information is available on the diversity of microbes involved in PAH degradation in the environment. We have designed generic PCR primers targeting the gene fragment encoding the Rieske iron sulfur center common to all PAH dioxygenase enzymes. These Rieske primers were employed to track dioxygenase gene population shifts in soil enrichment cultures following exposure to naphthalene, phenanthrene, or pyrene. PAH degradation was monitored by gas chromatograph with flame ionization detection. DNA was extracted from the enrichment cultures following PAH degradation. 16S rRNA and Rieske gene fragments were PCR amplified from DNA extracted from each enrichment culture and an unamended treatment. The PCR products were cloned and sequenced. Molecular monitoring of the enrichment cultures before and after PAH degradation using denaturing gradient gel electrophoresis and 16S rRNA gene libraries suggests that specific phylotypes of bacteria were associated with the degradation of each PAH. Sequencing of the cloned Rieske gene fragments showed that different suites of genes were present in soil microbe populations under each enrichment culture condition. Many of the Rieske gene fragment sequences fell into clades which are distinct from the reference dioxygenase gene sequences used to design the PCR primers. The ability to profile not only the bacterial community but also the dioxygenases which they encode provides a powerful tool for both assessing bioremediation potential in the environment and for the discovery of novel dioxygenase genes.     

Initial characterization of new bacteria degrading high-molecular weight polycyclic aromatic hydrocarbons isolated from a 2-year enrichment in a two-liquid-phase culture system

AIMS: To characterize some polycyclic aromatic hydrocarbons (PAH)-degrading microorganisms isolated from an enriched consortium degrading high molecular weight (HMW) PAHs in a two-liquid-phase (TLP) soil slurry bioreactor, and to determine the effect of low molecular weight (LMW) PAH on their growth and HMW PAH-degrading activity. METHODS AND RESULTS: Several microorganisms were isolated from a HMW-PAH (pyrene, chrysene, benzo[a]pyrene and perylene) degrading consortium enriched in TLP cultures using silicone oil as the organic phase. From 16S rRNA analysis, four isolates were identified as Mycobacterium gilvum B1 (99% identity),Bacillus pumilus B44 (99% identity), Microbacterium esteraromaticum B21 (98% identity), and to the genus Porphyrobacter B51 (96% identity). The two latter isolates have not previously been associated with PAH degradation. Isolate B51 grew strongly in the interfacial fraction in the presence of naphthalene vapours and phenanthrene compared with cultures without LMW PAHs. Benzo[a]pyrene was degraded in cultures containing a HMW PAH mixture but pyrene had no effect on its degradation. The growth of isolates B1 and B21 was improved in the aqueous phase than in the interfacial fraction for cultures with naphthalene vapours. Pyrene was required for benzo[a]pyrene degradation by isolate B1. For isolate B21, pyrene and chrysene were degraded only in cultures without naphthalene vapours. CONCLUSION: Consortium enriched in a TLP culture is composed of microorganisms with different abilities to grow at the interface or in the aqueous phase according to the culture conditions and the PAH that are present. Naphthalene vapours increased the growth of the microorganisms in TLP cultures but did not stimulate the HMW PAH degradation. SIGNIFICANCE AND IMPACT OF THE STUDY: New HMW PAH-degrading microorganisms and a better understanding of the mechanisms involved in HMW PAH degradation in TLP cultures.     

Characterization of cultures enriched from acidic polycyclic aromatic hydrocarbon-contaminated soil for growth on pyrene at low pH

Two polycyclic aromatic hydrocarbon (PAH)-contaminated soils of pH 2 were successfully used as inoculum to enrich cultures growing on phenanthrene and pyrene at different pHs, including pH 3. Selected pyrene-utilizing cultures obtained at pH 3, pH 5, and pH 7 were further characterized. All showed rapid [14C]pyrene mineralization at pH 3 and pH 5 and grew on pyrene at pH values ranging from 2 to 6. Eubacterial and mycobacterial 16S rRNA gene denaturing gradient gel electrophoresis fingerprinting and sequencing indicated that the cultures were dominated by a single bacterium closely related to Mycobacterium montefiorense, belonging to the slow-growing Mycobacterium sp. In contrast, a culture enriched on pyrene at pH 7 from a slightly alkaline soil sampled at the same site was dominated by Pseudomonas putida and a fast-growing Mycobacterium sp. The M. montefiorense-related species dominating the pyrene-utilizing cultures enriched from the acidic soils was also the dominant Mycobacterium species in the acidic soils. Our data indicate that a slow-growing Mycobacterium species is involved in PAH degradation in that culture and show that bacteria able to degrade high-molecular-weight PAHs at low pH are present in acidic PAH-contaminated soil.     

Degradation of pyrene, benz[a]anthracene, and benzo[a]pyrene by Mycobacterium sp. strain RJGII-135, isolated from a former coal gasification site.

The degradation of three polycyclic aromatic hydrocarbons (PAH), pyrene (PYR), benz[a]anthracene (BAA), and benzo[a]pyrene (BaP), by Mycobacterium sp. strain RJGII-135 was studied. The bacterium was isolated from an abandoned coal gasification site soil by analog enrichment techniques and found to mineralize [14C]PYR. Further degradation studies with PYR showed three metabolites formed by Mycobacterium sp. strain RJGII-135, including 4,5-phenanthrene-dicarboxylic acid not previously isolated, 4-phenanthrene-carboxylic acid, and 4,5-pyrene-dihydrodiol. At least two dihydrodiols, 5,6-BAA-dihydrodiol and 10,11-BAA-dihydrodiol, were confirmed by high-resolution mass spectral and fluorescence analyses as products of the biodegradation of BAA by Mycobacterium sp. strain RJGII-135. Additionally, a cleavage product of BAA was also isolated. Mass spectra and fluorescence data support two different routes for the degradation of BaP by Mycobacterium sp. strain RJGII-135. The 7,8-BaP-dihydrodiol and three cleavage products of BaP, including 4,5-chrysene-dicarboxylic acid and a dihydro-pyrene-carboxylic acid metabolite, have been isolated and identified as degradation products formed by Mycobacterium sp. strain RJGII-135. These latter results represent the first example of the isolation of BaP ring fission products formed by a bacterial isolate. We propose that while this bacterium appears to attack only one site of the PYR molecule, it is capable of degrading different sites of the BAA and BaP molecules, and although the sites of attack may be different, the ability of this bacterium to degrade these PAH is well supported. The proposed pathways for biodegradation of these compounds by this Mycobacterium sp. strain RJGII-135 support the dioxygenase enzymatic processes reported previously for other bacteria. Microorganisms like Mycobacterium sp. strain RJGII-135 will be invaluable in attaining the goal of remediation of sites containing mixtures of these PAH.     

Using population dynamics analysis by DGGE to design the bacterial consortium isolated from mangrove sediments for biodegradation of PAHs

There are many PAH-degrading bacteria in mangrove sediments and in order to explore their degradation potential, surface sediment samples were collected from a mangrove area in Fugong, Longhai, Fujian Province of China. A total of 53 strains of PAH-degrading bacteria were isolated from the mangrove sediments, consisting of 14 strains of phenanthrene (Phe), 13 strains of pyrene (Pyr), 13 strains of benzo[a]pyrene (Bap) and 13 strains of mixed PAH (Phe + Pyr + Bap)-degrading bacteria. All of the individual colonies were identified by 16S rDNA sequencing. Based on the information of bacterial PCR-DGGE profiles obtained during enrichment batch culture, Phe, Pyr, Bap and mixed PAH-degrading consortia consisted of F1, F2, F3, F4 and F15 strains, B1, B3, B6, B7 and B13 strains, P1, P2, P3, P5 and P7 strains, M1, M2, M4, M12 and M13 strains, respectively. In addition, the degradation ability of these consortia was also determined. The results showed that both Phe and mixed PAH-degrading consortia had the highest ability to degrade the Phe in a liquid medium, with more than 91% being degraded in 3 days. But the biodegradation percentages of Pyr by Pyr-degrading consortium and Bap by Bap-degrading consortium were relatively lower than that of the Phe-degrading consortium. These results suggested that a higher degradation of PAHs depended on both the bacterial consortium present and the type of PAH compound. Moreover, using the bacterial community structure analysis method, where the consortia consist of different PAH-degrading bacteria, the information from the PCR-DGGE profiles could be used in the bioremediation of PAHs in the future.