Effect of organic wastes on the plant-microbe remediation for removal of aged PAHs in soils

The effectiveness of in-situ bioremediation of polycyclic aromatic hydrocarbons (PAHs) may be inhibited by low nutrients and organic carbon. To evaluate the effect of organic wastes on the PAHs removal efficiency of a plant-microbe remediation system, contaminated agricultural soils were amended with different dosages of sewage sludge (SS) and cattle manure (CM) in the presence of alfalfa (Medicago sativa L.) and PAHs-degraders (Bacillus sp. and Flavobacterium sp.). The results indicated that the alfalfa mean biomasses varied from 0.56 to 2.23 g/pot in root dry weight and from 1.80 to 4.88 g/pot in shoot dry weight. Low dose amendments, with rates of SS at 0.1% and CM at 1%, had prominent effects on plant growth and soil PAHs degradation. After 60-day incubation, compared with about 5.6% in the control, 25.8% PAHs removal was observed for treatments in the presence of alfalfa and PAHs-degraders; furthermore, when amended with different dosages of SS and CM, the removed PAHs from soils increased by 35.5%-44.9% and 25.5%-42.3%, respectively. In particular, the degradation of high-molecular-weight PAHs was up to 42.4%. Dehydrogenase activities (DH) ranged between 0.41 and 1.83 μupg triphenylformazan/(g dry soil. hr) and the numbers of PAHs-degrading microbes (PDM) ranged from 1.14× 10⁶ to 16.6× 10⁶ most-probable-number/g dry soil. Further investigation of the underlying microbial mechanism revealed that both DH and PDM were stimulated by the addition of organic wastes and significantly correlated with the removal ratio of PAHs. In conclusion, the effect of organic waste application on soil PAHs removal to a great extent is dependent on the interactional effect of nutrients and dissolved organic matter in organic waste and soil microorganisms.     

Biodegradation of benzo[a]pyrene in soil by Mucor sp. SF06 and Bacillus sp. SB02 co-immobilized on vermiculite

Two indigenous microorganisms, Bacillus sp. SB02 and Mucor sp. SF06, capable of degrading polycyclic aromatic hydrocarbons （PAHs） were co-immobilized on vermiculite by physical adsorption and used to degrade benzo[a] pyrene （BaP）. The characteristics of BaP degradation by both free and co-immobilized microorganism were then investigated and compared. The removal rate using the immobilized bacterial-fungal mixed consortium was higher than that of the freely mobile mixed consortium. 95.3% of BaP was degraded using the co-immobilized system within 42 d, which was remarkably higher than the removal rate of that by the free strains. The optimal amount of inoculated co-immobilized system for BaP degradation was 2%. The immobilized bacterial-fungal mixed consortium also showed better water stability than the free strains. Kinetics of BaP biodegradation by co-immobilized SF06 and SB02 were also studied. The results demonstrated that BaP degradation could be well described by a zero-order reaction rate equation when the initial BaP concentration was in the range of 10--200 mg/kg. The scanning electronic microscope （SEM） analysis showed that the co-immobilized microstructure was suitable for the growth of SF06 and SB02. The mass transmission process of co-immobilized system in soil is discussed. The results demonstrate the potential for employing the bacterial-fungal mixed consortium, co-immobilized on vermiculite, for in situ bioremediation of BaP.     

Degradation of polycyclic aromatic hydrocarbons by Pseudomonas sp. JM2 isolated from active sewage sludge of chemical plant

It is important to screen strains that can decompose polycyclic aromatic hydrocarbons (PAHs) completely and rapidly with good adaptability for bioremediation in a local area. A bacterial strain JM2, which uses phenanthrene as its sole carbon source, was isolated from the active sewage sludge from a chemical plant in Jilin, China and identified as Pseudomonas based on 16S rDNA gene sequence analysis. Although the optimal growth conditions were determined to be pH 6.0 and 37℃, JM2 showed a broad pH and temperature profile. At pH 4.5 and 9.3, JM2 could degrade more than 40% of fluorene and phenanthrene (50 mg/L each) within 4 days. In addition, when the temperature was as low as 4℃, JM2 could degrade up to 24% fluorene and 12% phenanthrene. This showed the potential for JM2 to be applied in bioremediation over winter or in cold regions. Moreover, a nutrient augmentation study showed that adding formate into media could promote PAH degradation, while the supplement of salicylate had an inhibitive effect. Furthermore, in a metabolic pathway study, salicylate, phthalic acid, and 9-fluorenone were detected during the degradation of fluorene or phenanthrene. In conclusion, Pseudomonas sp. JM2 is a high performance strain in the degradation of fluorene and phenanthrene under extreme pH and temperature conditions. It might be useful in the bioremediation of PAHs.     

Adaptability of microbial inoculators and their contribution to degradation of mineral oil and PAHs

Five dominant bacteria strains（A cetobacter sp., Alcdigenes sp., Micrococcus sp., Arthrobacter sp. and Bacillus sp.） and five fungi strains （Cephalosporium sp. Ⅰ, Cephalosporlum sp. Ⅱ, Aspergillus sp. Ⅰ, Aspergillus sp. Ⅱ and Fusarium sp.） isolated from petroleum-contaminated soil were used to assess the potential capability of mineral oil and PAH enhanced degradation separately and jointly using the batch liquid medium cultivation with diesel oil spiked at 1000 mg/L. The experiment was performed on a reciprocal shaker in the darkness at 25℃ to 30℃ for 100 d. The dynamic variation in the activity of microbial inoculators in each treatment and the degradation of the target pollutants during the period of experiment were monitored. Results showed a more rapid biodegradation of mineral oil and PAHs at the beginning of the experiment （about 20 d） by dominant bacteria, fungi and their mixture than that of the indigenous microorganisms, however, thereafter an opposite trcnd was exhibited that the removal ratio by indigenous microorganisms was superior to any other dominant treatments and the tendency lasted till the end of the experiment, indicating the limited competitive capability of dominant microorganisms to degrade the contaminants, and the natural selection of indigenous microorganisms for use in the removal of the contaminants. At the end of the experiment, the removal ratio of mineral oil ranged from 56.8 % to 79.2 % and PAHs ranged from 96.8 % to 99.1% in each treatment by microbial inoculators,     

Photolysis of polycyclic aromatic hydrocarbons on soil surfaces under UV irradiation

Photolysis of some polycyclic aromatic hydrocarbons (PAHs) on soil surfaces may play an important role in the fate of PAHs in the environment.Photolysis of PAHs on soil surfaces under UV irradiation was investigated.The effects of oxygen,irradiation intensity and soil moisture on the degradation of the three PAHs were observed.The results showed that oxygen,soil moisture and irradiation intensity enhanced the photolysis of the three PAHs on soil surfaces.The degradation of the three PAHs on soil surfaces is related to their absorption spectra and the oxidation-half-wave potential.The photolysis of PAHs on soil surfaces in the presence of oxygen followed pseudo first-order kinetics.The photolysis half-lives ranged from 37.87 days for benzo[a]pyrene to 58.73 days for phenanthrene.The results indicate that photolysis is a successful way to remediate PAHs-contaminated soils.     

Bioaugmentation of DDT-contaminated soil by dissemination of the catabolic plasmid pDOD

A plasmid transfer-mediated bioaugmentation method for the enhancement of dichlorodiphenyltrichloroethane (DDT) degradation in soil was developed using the catabolic plasmid pDOD from Sphingobacterium sp. D-6. The pDOD plasmid could be transferred to soil bacteria, such as members of Cellulomonas, to form DDT degraders and thus accelerate DDT degradation. The transfer efficiency of pDOD was affected by the donor, temperature, moisture, and soil type. Approximately 50.7% of the DDT in the contaminated field was removed 210 days after the application of Escherichia coli TG I (pDOD-gfp). The results suggested that seeding pDOD into soil is an effective bioaugmentation method for enhancing the degradation of DDT.     

Effect of struvite and organic acids on immobilization of copper and zinc in contaminated bio-retention filter media

Few studies have been carried out to connect nutrient recovery as struvite from wastewater and sustainable utilization of the recovered struvite for copper and zinc immobilization in contaminated soil. This study revealed the effect of struvite on Cu and Zn immobilization in contaminated bio-retention soil in the presence of commonly exuded plant organic acids. The research hypothesis was that the presence of both struvite and organic acids may influence the immobilization of Cu and Zn in soil. The outcome of this research confirmed that more than 99% of Cu and Zn was immobilized in bio-retention filter media by struvite application. Water-soluble Cu and Zn concentrations of struvite treated soil were less than 1.83 and 0.86 mg/kg respectively, and these concentrations were significantly lower compared to the total Cu and Zn content of 747.05 mg/kg in the contaminated soil. Application of struvite to Cu- and Zn-contaminated soil resulted in formation of compounds similar to zinc phosphate tetrahydrate (Zn₃(PO₄)₂?4H₂O) and amorphous Cu and Zn phases. Struvite was effective in heavy metal remediation in acidic soil regardless of the presence of Ca impurities in struvite and the presence of plant organic acids in soil. Overall, this study revealed that struvite recovered from wastewater treatment plants has potential for use as an amendment for heavy metal remediation in contaminated bio-retention soil.     

Characteristics for the hybrid cell Foaz obtained from the  protoplast fusion between yeast and photosynthetic bacteria in soybean processing wastewater

The optimal pH and temperature, maximum specific degradation rate, half rate constant and flocculation rate for the hybrid cell Foaz were measured in the reaction for the degradation of soybean processing wastewater(SPW) in this study. The optimal pH and temperature for Foaz in SPW were the same as those of its parental strains Saccharomyces cerevisiae Y9407 and Rhodobacter sphaeroides P9479, but the flocculation rate, the maximum specific degradation rate and the half rate constant for Foaz were higher than those of its parental strains. The results suggest that the characteristics of the inter kingdom fusant Foaz constructed from the protoplast fusion between the eukaryote cell yeast S.cerevisiae and the prokaryote cell photosynthetic bacteriaR. sphaeroides may favor degrading organic pollutant in SPW and removing biomass from the effluent.     

A reactor system combining reductive dechloirnation with cometabolic oxidation for complete degradation of tetrachloroentylene

A laboratory sequential anaerobic aerobic bioreactor system, which consisted of an anaerobic fixed film reactor and two aerobic chemostats, was set up to degrade tetrachloroethylene (PCE) without accumulating highly toxic degradation intermediates. A soil enrichment culture, which could reductively dechlorinate 900μM (ca. 150 mg/L) of PCE stoichiometrically into cis-1,2-dichloroethylene ( cis-DCE), was attached to ceramic media in the anaerobic fixed film reactor. A phenol degrading strain, Alcaligenes sp. R5, which can efficiently degrade cis-DCE by co metabolic oxidation, was used as inoculum for the aerobic chemostats consisted of a transformation reactor and a growth reactor. The anaerobic fixed film bioreactor showed more than 99 % of PCE transformation into cis DCE in the range of influent PCE concentration from 5μM to 35μM at hydraulic retention time of 48h. On the other hand, efficient degradation of the resultant cis-DCE by strain R5 in the following aerobic system could not be achieved due to oxygen limitation. However, 54% of the maximum cis-DCE degradation was obtained when 10 μmol of hydrogen peroxide (H₂O₂) was supplemented to the transformation reactor as an additional oxygen source. Further studies are needed to achieve more efficient co metabolic degradation of cis DCE in the aerobic reactor.     

Investigation of physico-chemical properties and microbial community during poultry manure cocomposting process

Co-composting of poultry manure and rubber wood sawdust was performed with the ratio of 2:1 (V/V) for a period of 60 days. An investigation was carried out to study the extracellular enzymatic activities and structural degradation utilizing Fourier transform infrared spectroscopy (FT-IR), thermogravimetry and differential thermal analysis (TG/DTA) and scanning electron microscopy (SEM). The microbial succession was also determined by using denaturing gel gradient electrophoresis (DGGE). The compost was able to reach its highest temperature of 71 ℃ at day 3 and stabilized between 30 and 40 ℃ for 8 weeks. CMCase, FPase and β-glucosidase acted synergistically in order to degrade the cellulosic substrate. The xylanase activities increased gradually during the composting and reached the peak value of 11.637 U/g on day 35, followed by a sharp decline. Both LiP and MnP activities reached their peak values on day 35 with 0.431 and 0.132 U/g respectively. The FT-IR spectra revealed an increase in aromaticity and a decrease in aliphatic compounds such as carbohydrates as decomposition proceeded. TGA/DTG data exhibited significant changes in weight loss in compost samples, indicating degradation of organic matter. SEM micrographs showed higher amounts of parenchyma exposed on the surface of rubber wood sawdust at day 60, showing significant degradation. DGGE and 16S rDNA analyses showed that Burkholderia sp., Pandoraea sp., and Pseudomonas sp. were present throughout the composting process. Ornithinibacillus sp. and Castellaniella ginsengisoli were only found in the initial stage of the composting, while different strains of Burkholderia sp. also occurred in the later stage of composting.     

耐冷腐殖酸吸附态PAHs降解菌筛选及其降解特性

为了寻找自然环境中高效PAHs降解菌,并应用于北方寒冷地区PAHs污染土壤修复,从沈抚灌渠冻融土壤中筛选出一株以腐殖酸(HA)吸附态PAHs为碳源和能源且生长良好的耐冷菌株,结合其生理生化特征和16S rDNA序列比对,鉴定此菌株为假单胞菌(Pseudomonas sp.SDR4),并研究了其对冻融土壤中HA吸附态PAHs的降解性能.结果表明:Pseudomonas sp.SDR4对冻融土壤中Phe、Pyr和Ba P均具有一定的降解能力,42 d降解率分别为73.88%、64.88%和49.39%.加入HA能够提高其对Phe、Pyr和Ba P的降解率,42 d降解率分别提高15.9%、13.8%和8.6%;在降解初期加入HA可显著提高Phe、Pyr和Ba P的降解速率,第1周,降解速率分别提高37.8%、28.4%和39.1%,但在后期促进效果减弱.若要在寒冷地区选择Pseudomonas sp.SDR4作为固定化菌株,可添加HA提高其修复效果.本研究为北方寒冷地区PAHs污染土壤修复提供了新的固定化菌种.     

Isolation of marine benzo[a]pyrene-degrading Ochrobactrum sp. BAP5 and proteins characterization

A bacterial strain BAP5 with a relatively high degradation ability of benzo[a]pyrene (BaP) was isolated from marine sediments of Xiamen Western Sea, China and identified as Ochrobactrum sp. according to 16S rRNA gene sequence as well as Biolog microbial identification system. Strain BAP5 could grow in mineral salt medium with 50 mg/L of BaP and degrade about 20% BaP after 30 d of incubation. Ochrobactrum sp. BAP5 was able to utilize other polycyclic aromatic hydrocarbons (PAHs) (such as phenanthrene, pyrene and fluoranthene) as the sole carbon source and energy source, suggesting its potential application in PAHs bioremediation. The profile of total soluble protein from Ochrobactrum sp. BAP5 was also investigated. Some over- and special-expressed proteins of strain BAP5 when incubated with the presence of BaP were detected by two-dimensional polyacrylamide gel electrophoresis, and found to be related with PAHs metabolism, DNA translation, and energy production based on peptide fingerprint analysis through matrix-assisted laser desorption/ionization-time of flight mass spectrometry.     

采用固定化技术处理土壤中菲、芘污染物

采用动胶杆菌(Zoogloea sp.)固定化技术包埋来降解土壤中菲、芘污染物,在不同接种量、不同系列浓度下,对降解效果进行了测定.结果表明:5%的接种量最为合理,在168h时,固定化细菌对菲、芘的降解率达84.89%和76.94%;而在相同条件下土著菌降解仅达到27.85%和19.65%,因此动胶杆菌(Zoogloea sp.)具有更好的降解能力.另外,还用电镜观察研究了动胶杆菌在载体中的分布形态,表明了固定化细菌降解土壤中菲、芘具有较高的优势.     

生物炭固定化多环芳烃高效降解菌剂的制备及稳定性

高效多环芳烃降解微生物在污染环境中存活并保持一定生物量是实现生物强化修复的前提.本研究通过优选生物炭,优化生物炭固定化多环芳烃高效降解菌Martelella sp.AD-3的制备条件以及评估生物炭固定化菌剂的稳定性,期望获得具有应用前景的生物材料.结果显示,稻壳生物炭比表面积及孔隙大、Zeta电位高、固定化菌剂去除效果好,选择其作为固定化AD-3菌的载体.电镜观察及固定化菌剂对菲的去除率表明,固定化培养基为3% LB,接种量为2.9×10⁸ CFU·mL^-1,固定2 d时,稻壳固定化菌剂负载AD-3量最多,对菲的去除速率可达8.08 mg·L^-1·h^-1.室温保存21 d后,稻壳生物炭固定化菌剂对菲的去除速率仍达到4.46 mg·L^-1·h^-1,表明稻壳生物炭固定化AD-3菌不仅保持了菌对菲的高效降解能力,而且延长了降解微生物的保存时间,这为多环芳烃污染土壤修复提供了良好的生物修复功能材料.     

接种Penicilliumsp.和根际分泌物对土壤甲磺隆的协同降解研究

通过接种Penicillium sp.和模拟小麦根际环境的方法,研究了甲磺隆在Penicillium sp.和小麦根际分泌物协同作用下的生物降解特性.结果表明,根系分泌物丰富了土著微生物和外源微生物,对甲磺隆的降解具有显著的促进作用.接种Penicillium sp.的根际土壤中甲磺隆降解半衰期为8.6 d,其降解速率是接种Penicillium sp.的非根际土壤的1.8倍,是普通根际土壤的2.7倍.继续追加甲磺隆的试验表明,接种菌株Penicillium sp.对甲磺隆的降解具有可持续性.     

青顶拟多孔菌对单一和复合多环芳烃的降解特性

利用中国东北林区普遍存在白腐菌——青顶拟多孔菌,降解单一和复合多环芳烃,分别测定了菲、蒽、芘于11,22,33d的累积降解率.结果显示,对于单一多环芳烃,该菌种降解能力由强到弱依次为菲>蒽>芘,33d累积降解率依次为96.56%、94.76%和57.53%;对复合多环芳烃降解中,菲和芘的累积降解率分别为99.46%和61.09%.在复合多环芳烃的降解研究中发现,少量蒽的加入,刺激了菌种对菲和芘的降解,使菲和芘的降解率分别提高了2.9%和3.56%.由此提示,在研究降解高环、难降解多环芳烃时,可利用低环多环芳烃对菌种的刺激作用,在体系内形成高、低环多环芳烃的共代谢,以达到更加高效降解多环芳烃的目的.     

2株海洋石油降解细菌的降解能力

为实施海洋石油污染的生物治理,从厦门储油码头油污水中分离得到了2株石油降解菌.它们能够在以柴油、萘或芘为唯一碳源的培养基中生长,并适应于海洋环境的温度、pH和盐度.它们对萘都有很强的降解能力,3d内降解率可达87.53%和84.01%;7 d内对芘降解率分别为8.35%、5.37%.经16S rDNA同源性分析表明2菌株之间及其与施氏假单胞菌的同源性皆为99%;Biolog生化鉴定也表明它们为不同的菌株.通过兼并PCR扩增,序列分析发现2种菌编码完全相同的萘双加氧酶基因,该基因与其它假单胞菌的萘双加氧酶大亚基有98%同源性.     

金发草对土壤中菲、芘的修复机制

采用盆栽试验法,研究岩生植物金发草(Pogonatherum paniceum L.)对土壤中芘、菲的去除效果与修复机制.结果显示,在试验浓度范围(20～322 mg·kg^-1)内,种植金发草能有效去除土壤中芘、菲污染. 70 d后,菲、芘去除率分别为50.97%～86.77%、 46.45%～76.7%;比对照1(加0.1% NaN₃)高63.56%、 58.6%,比对照2(无NaN₃)高46.09%、 42.92%.金发草能吸收、富集部分菲和芘,根、茎叶组织中菲、芘含量随菲、芘添加浓度的升高而增大,且根部大于茎叶部、芘大于菲,但生物浓缩系数却逐渐减小.修复过程中,非生物因子、植物代谢、富集、微生物降解对菲的去除率分别为5.1%、 0.32%、 4.22%、 17.47%,对芘的去除率分别为2.56%、 4.27%、 2.01%、 15.68%;植物-微生物间的交互作用对菲、芘的去除率分别为41.56%、 36.64%.说明植物-微生物交互作用是金发草修复土壤中菲芘污染的主要机制.