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Objective: We screened and isolated bacterial strains from the perennial administration quinclorac paddy fields to degrade quinclorac., Methods: Strain MC-10, which can degrade quinclorac efficiently, was screened by enrichment and selective medium. The strain was identified by morphological, physio-biochemical characteristics and 16S rDNA gene sequence analysis., Results: MC-10 was identified as Arthrobacter sp. Under the optimal growth conditions with inoculum concentration of 5%, at 28 °C, pH 7 for 7 d, MC-10 degraded more than 90% of quinclorac. MC-10 can effectively degrade quinclorac when quinclorac initial concentration at 1 mg/L--100 mg/L. And the strain MC-10 has a good ability to survive in the soil. More than 70% quinclorac in the soil can be degraded efficiently after 7 days of cultivation., Conclusion: Arthrobacter sp. MC-10 could be a promising microorganism in dealing with quinclorac pollution.

Objective: In order to study the diversity and distribution of Benzoyl coenzyme A reductase (bcrA) and oxygenase components of 1H-2-oxoquinoline 8-monooxygenase (oxoO) gene in a lab scale denitrifying bioreactors for treating quinoline-containing wastewater., Methods: Genomic microbial DNA was extracted from the biofilm samples of bioreactor. Based on the known oxoO genes sequences in GenBank, we designed primers for oxoO gene amplification. Using our designed oxoO gene primers and a pair of degenerate primers of bcrA gene obtained from literature, we amplified the DNA samples. And the amplicons were used for constructing clone libraries of oxoO and bcrA gene. We also performed quantification analysis of these two genes in bioreactor by using Real-time qPCR method., Results: The quantification analysis showed gradual increase of the bcrA gene abundance and reduction of the oxoO gene abundance along with time. The clone library analysis of these two genes indicated that most clones in bcrA gene clone library having more than 97% sequence similarities to the known bcrA gene of Thauera bacteria and others only having 74% - 86% sequence similarities to bcrA gene sequences. Whereas, only a few clones in the oxoO gene clone library have 99% sequence similarities to that gene of Pseudomonas putida. But the sequences of most clones only distantly related with known oxoO genes., Conclusions: This study showed a high bcrA and oxoO gene diversity, with some new gene sequences, in the lab scale denitrifying bioreactors. The abundance of bcrA and oxoO gene changed remarkably during the running of bioreactor, and closely related with the performance of bioreactor. Therefore, bcrA and oxoO genes have potential to be used as molecule markers to monitor the process of treating quinoline containing wastewater.

Microbial flora composition of microbial fuel cells (MFC) is important to the electricity generation. Four bacterium strains Q1, b, c and d which represent all different morphology of culturable bacterium were isolated from a MFC using 200 mg x L(-1) quinoline as the fuel and operating for at least 210 days. Strains Q1, c and d were Pseudomonas sp. based on 16S rDNA sequence analysis, while strain b was Burkholderia sp. Double-chamber MFCs using 200 mg x L(-1) quinoline and 300 mg x L(-1) glucose as the fuel and potassium ferricyanide as the electron acceptor were constructed. Results showed that strain b, c and d were non-electrogenesis. The electrical charges of MFC inoculated electrogenesis strain Q1 with non-electrogenesis strain b, c and d respectively were 3.00, 3.57 and 5.13C, and the columbic efficiency were 3.85%, 4.59% and 6.58%, which were all lower than that inoculated with pure Q1, because of the interspecific competition of electrogenesis and non-electrogenesis bacteria. Combinations of Q1 with the other three strains respectively resulted in 100% of quinoline degradation rates within 24h, which is better than pure cultures, that is, mixed microbial populations perform better in MFC when complex organics are used as the fuel. GC/MS analyses showed that only 2(1H)-quinolinone and phenol existed in the effluent of the MFC, which was inoculated with only Q1 or mixed bacteria.

A bacterial strain BW003, which could utilize quinoline as sole carbon, nitrogen and energy source, was isolated from the activated sludge in a coking wastewater treatment plant. According to the 16S rRNA gene sequence analysis, the strain was identified as Pseudomonas sp. Biodegradation experiments showed that the strain could degrade 192-911 mg/L of quinoline efficiently within 3-8 h, and the removal rates of quinoline were ranged from 96% to 98%. The optimum conditions for the degradation were 30 degrees C and pH 8. Metabolic products analysis revealed that at least 43% quinoline was first transformed into 2-hydroxyquinoline, 0.69% 2-hydroxyquinoline was then transformed into 2,8-dihydroxyquinoline, and subsequently into 8-hydroxycoumarin in the process of biodegradation. Additionally, at least 48% of nitrogen in quinoline was transformed into NH3-N directly and external carbon source could promote the nitrogen transformation, demonstrating that the quinoline and its metabolic products could be eliminated if controlling proper C/N ratio.

This study focused on the effects of decolorization products of reactive black 5 (RB5) on anaerobic decolorization of direct yellow 11 (DY11) by Rhodopseudomonas palustris W1 and its reaction mechanisms. The results showed that the decolorization products of RB5 could obviously accelerate biological decolorization rate of DY11. For initial concentration of 200 mg/L of DY11, the addition of decolorization products of RB5 resulted in that the decolorization kinetic constant K was increased from 17 mg/(L x h) to 42.5 mg/(L x h), followed by an further increase to 48.8 mg/(L x h) after optimization of RB5 supplement. Cyclic voltammogram analysis demonstrated that the decolorization products of RB5 presented electrochemical activity due to the presence of redox electron transfer mediators, as indicated by an observation of two current peaks of reversible oxidation and reduction appeared at potential of ca. 83 mV and -200 mV, respectively. According to LC-MS and FT-IR analysis, the electrochemically activated species of the decolorization products were characterized to be 7-amino-8-hydroxy-1, 2-naphthaquinone-3, 6-disulphonate-1, 2-diimine (TAHNDSDP-1). TAHNDSDP-1 with quinine-like structure was able to transfer between its oxidative and reductive forms by transferring 2[H], which was supposed to be the redox mediator to shuttle electrons from electron donors to azo dyes, thus, improving the reduction of de materials.

Objective: We compared the microbial communities of two denitrifying bioreactors acclimated by quinoline and indole under identical condition., Methods: We acclimated two reactors by using the same seeding sludge and acclimating conditions. When both reactors reached steady stage with a high pollutant removal capacity after 6 weeks adaptation, we constructed the 16S rDNA clone libraries to analyze the structure of microbial communities of those 2 bioreactors., Results: Despite the same seeding sludge and identical acclimating condition, molecular ecological analysis showed distinctly different communities of two reactors. All operational taxonomic units (OTUs) of 16S rDNA clone library of quinoline acclimated bioreactor were affiliated to Betaproteobacteria, whereas in library of indole acclimated bioreactor, the percentage of Betaproteobacteria was only 56.3%. Results showed that microbial diversity in indole acclimated community was higher. Clones (73%) in quinoline acclimated community were Thauera related OTUs from the Rhodocyclaceae family. But OTUs from the families of Comamonadaceae, Alcaligenaceae and Rhodocyclaceae were dominant OTUs in indole acclimated community. The most dominant OTU from Comamonadaceae was 28.7% in clone library., Conclusion: The type of pollutants in the wastewater had a strong effect on the selection of population in microbial community. Our study was the first report comparing the microbial structure of two effective denitrifying communities which could efficiently degrade quinoline and indole.

A quinoline-degrading bacterium QL2, which utilizes quinoline as sole source of carbon, nitrogen and energy, was isolated from activated sludge in a coke-plant wastewater biological treatment system. According to the morphological characteristics, physiological and biochemical characteristics, and sequence analysis of 16S rRNA, the strain was identified as Rhodococcus sp.. The optimal temperature, initial pH, and shaker rotary speed for strain QL2 utilizing quinoline are 35-42 degrees C, pH 8-9, and 150 r/min, respectively. Extra nitrogen sources stimulate the isolate growth on quinoline, and inorganic nitrogen better than organic nitrogen, NH4+ -N better than NO3(-) -N. The degradation reaction of quinoline by strain QL2 can be described with zero order kinetic equation within the initial quinoline concentrations of 60-680 mg/L. When the initial concentration was 150 mg/L, quinoline was degraded completely in 8 hours and TOC removal efficiency was 70% in 14 hours. This bacterium produced pigmented compounds, and ring nitrogen was released into the growth medium as ammonium. The main intermediate in the degradation pathway was 2-hydroxyquinoline by the analysis of HPLC and GC/MS. With a broad range of substrate utilization, the strain can degrade phenol, naphthalene, pyridine, and some other kinds of aromatic compounds.