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Biodegradation characteristics of pyrene by intact cells and spores of Brevibacillus brevis were investigated. The results revealed that the degradation efficiency of 1 mg · L(-1) pyrene by B. brevis intact cells reached 53% within 5 d. Four hydroxy metabolites were detected by LC-MS/MS during the degradation of pyrene by intact cells and intracellular enzymes, including 1-hydroxy-pyrene, 9- phenanthrol, α-naphthol and β-naphthol. The amount of products first increased and then declined in the degradation system with intact cells, while the macromolecular metabolites showed a continuous accumulation tendency in the degradation system with intracellular enzymes, proving that some degrading enzymes of B. brevis could be induced by the products generated during the degradation, and then the enzymes induced could further degrade these degradation products. The amount of cells germinated from spores in MSM containing pyrene was 1.5 x 10(9) cells · L(-1), and the degradation rate of pyrene (1 mg · L(-1)) within 5 d reached 15%.

So far, the information regarding enhanced degradation and biodegradation mechanisms of TPhT, an endocrine disruptor, is severely limited. Whether dearylation during TPhT degradation occurs successively or synchronously is not revealed clearly. To deal with these problems, this study focused on the biodegradation of TPhT and its metabolites by Bacillus thuringiensis through the acceleration of Tween 80. The results showed that Tween 80 obviously increased the TPhT solubility. After degradation by cells in the presence of 80 mg L-1 Tween 80 for 2 d, the residual TPhT at 1 mg L-1 initially was decreased to 48.4%. During the biodegradation process, Tween 80 significantly reduced intracellular Na+, NH+4: and Mg2+ release, and increased extracellular Cl- , PO(3-)4 and K+ utilization. Metabolites analysis revealed that phenyltin biodegradation initially proceeded by cleaving the aromatic ring, not by splitting the covalent bonds between the benzene rings and tin atom. Ring-cleavage reactions in the benzenes of TPhT occurred individually and synchronously, producing diphenyltin, monophenyltin and tin accordingly.

To investigate the pathway and mechanism of triphenyltin (TPhT) biodegradation by Klebsiella pneumoniae, and the effects of TPhT on cells during the degradation process, the alteration of carbon utilization ability of the strain after dealing with different concentrations of TPhT was studied by the Biolog method, and the degradation pathway of TPhT was explored by GC-MS and X-ray photoelectron spectroscopy (XPS). After degradation for 2 h, the nutrient utilization capacity of K. pneumoniae was significantly improved by 1 mg x L(-1) TPhT. Atomic force microscope observation found that exposure to TPhT changed the cellular morphology, inducing the apoptosis of some cells, but most of the cells still maintained intact and had smooth cell wall. The efficiencies of TPhT removal by intracellular enzyme were up to 66.0% within 120 h, which demonstrated that endoenzyme was more effective than the intact cells. The results of GC-MS and XPS revealed that during the biodegradation process, TPhT was transformed to diphenyltin, monophenyltin and finally inorganic tin.

A strain which could utilize BaP as a sole carbon and energy source and efficiently degrade benzo[a] pyrene (BaP) was isolated from the contaminated sediments of Guiyu, Guangdong province, China. The strain was identified as Brevibacillus brevis based on physiological and biochemical experiments together with 16S rRNA sequence analysis. The experimental results showed that the biodegradation rate of BaP by B. brevis in 7 days was 51.35%. The study also demonstrated that pH, temperature, bacterial dosage, initial concentration of BaP and processing time were important factors for BaP degradation. B. brevis could tolerate wide pH and temperature ranges, from 2 to 12 degrees C and 25 to 40 degrees C, respectively. The optimum condition for BaP degradation was pH 7 and 25 degrees C. With the increase of B. brevis inoculation amount, the degradation efficacy displayed an initial increasing trend and then came to a plateau. And the increase of BaP concentration led to the enhancement of BaP degradation. Addition of salicylic, succinate and phthalate showed no obvious positive effect on BaP biodegradation. After degradation of BaP, the surface of B. brevis was wrinkled, and became depressed and deformed over time.

The degradation characteristics of decabromodiphenyl ether (BDE-209) by crude enzyme from Pseudomonas aeruginosa were investigated. The results revealed that the degradation efficiency of the intracellular enzyme excreted from this bacterial strain reached 69.22% after incubation with 1 mg x L(-1) BDE-209 for 12 h. Temperature, pH, enzyme concentration and BDE-209 concentration all influenced the ability of crude enzyme to degrade BDE-209. When the BDE-209 concentration was 1 mg x L(-1), the optimal condition for enzymatic degradation was temperature 30 degrees C and pH 7.5, and the degradation rate increased with increasing enzyme concentration. The degradation process of BDE-209 by intracellular enzyme of the strain conformed to the first-order kinetic model. The highest reaction rate was achieved when the initial concentration of BDE-209 was 1 mg x L(-1) and the half-life of this substrate was 6.9 h. In addition, the biodegradation of BDE-209 can be well described by enzymatic reaction of high concentration substrate inhibition, with a maximum substrate utilization rate of 0.133 mg x (L x h)(-1), a Michaelis-Menten constant of 0.642 mg x L(-1), and an inhibitory constant of 1.558 mg x L(-1), respectively.

The characteristics of Cu2+ and Cd2+ biosorption by Stenotrophomonas maltophilia (S. maltophilia) under different biomass, metal concentration and glutaraldehyde content were studied and the correlations among metal biosorption, NO3- removal and ion release were analyzed. The mechanism was explored through ion biosorption, exchange, conversion and release. The experimental results demonstrated that S. maltophilia was an efficient strain to remove Cu2+ and Cd2+. The biosorption efficiencies of Cu2+ and Cd2+ achieved 96.3% and 83.9%, respectively after dealing with 0.05 mmol x L(-1) aqueous solutions for 120 min with dry biosorbent dosage of 0.2 g x L(-1). Cu2+ and Cd2+ biosorption by S. maltophilia included surface adsorption, transmembrane active transportation, bioaccumulation of NO3- and reduction of NO3- to NO2-. The intracellular transfer and reduction of NO3- to NO2- during biosorption by S. maltophilia were energy-consuming biological processes. It could also promote the release of Cl-, PO4(3-), SO-4(2-), Na+, NH4+, K+ and Ca2+. From FTIR investigation, involvement of various functional groups like acetylamino, hydroxyl and carboxyl in the binding of Cu2+ and Cd2+ was evident. Moreover, XPS results proved that the valence state of Cu2+ and Cd2+ did not changed by biosorption.

Effects and mechanisms of heavy metals Cu, Cd and Pb on the growth of white-rot fungus P. chrysosporium and its ability of BDE-209 degradation were studied. The results showed that low concentrations of heavy metals (or = 1 mg x L(-1)) stimulated the growth of P. chrysosporium with the order of CdPbCu when 1 mg x L(-1) of each heavy metal was concerned, while high concentrations (1 mg x L(-1)) depressed it. P. chrysosporium degraded BDE-209 efficiently with degradation efficiency reaching 69.7% after 7 days. The presence of heavy metals significantly influenced the capability of P. chrysosporium to decompose BDE-209 (P0.05). Low concentrations of Cu (or = 1 mg x L(-1)) and Cd (or = 0.5 mg x L(-1)) accelerated the degradation of BDE-209 and the degradation efficiency was enhanced from 69.7% to 84.4% when 1 mg x L(-1) Cu was present, while Pb had negative effect. On the other hand, all three metals under high concentrations (1 mg x L(-1)) showed depressed effects on the degradation in the order of CdPbCu. The growth of P. chrysosporium did not completely positively correlate with the degradation capability of BDE-209. The degradation of BDE-209 by P. chrysosporium conformed to the first-order kinetic model. The reaction rate constant k raised firstly and then declined with increasing concentrations of Cu and Cd, and the highest k of 0.321 2 achieved in the presence of 1 mg x L(-1) Cu. By contrast, the constant k declined all the way when Pb existed. A further investigation into the effects of heavy metals on degradation of BDE-209 by extracellular enzymes derived from P. chrysosporium was conducted, and the distance correlation analysis of the degradation by extracellular enzymes and the whole cell was carried out. The results demonstrated that the degradation by extracellular enzymes and the whole cell was 63.7%, 69.7% separately, showing no significant difference of degradation capability between them, which proved that the extracellular enzymes played dominating role in the degradation of BDE-209. Furthermore, the distance correlation coefficient R were all greater than 0.9 when three heavy metals existed, certificating that heavy metals affected the degradation of BDE-209 through the interaction between extracellular enzymes and heavy metals.

A hydroponic experiment was conducted to investigate the cation exchanges during the process of Cd2+ absorption by Alfalfa in aqueous solution. The absorption efficiency of Alfalfa plants with 0-10 mg x L(-1) Cd2+ treatments, changes of Na+, K+, Mg2+, Ca2+ and NH4(+) concentration, and the variation of pH values at different absorption time (0, 1, 2, 4, 8, 12, 24 and 72 h) were studied separately. The multiple linear regressions between Cd2+ absorption and cation variation were analyzed. The results indicated that when Cd2+ concentrations were 0.1, 1, 5, 10 mg x L(-1), the absorption efficiencies of Cd2+ by Alfalfa after 72 h were 85.86%, 52.14%, 15.97% and 7.81%. Cation exchange was involved in the removal of Cd2+ by Alfalfa in aqueous solution. Except for NH4(+), the concentrations of cationic metals Na+, K+, Mg2+ and Ca2+ in aqueous solution increased over time, which increased 11.30% - 61.72%, 21.44% - 98.73%, 24.09% - 8.90% and 37.04% - 191.96%, respectively. Kinetic studies illuminated that the release of Na+, K+, Mg2+ and Ca2+ by Alfalfa in Cd2+ solution with initial concentrations of 0, 0. 1, 1, 5, 10 mg x L(-1) best fitted pseudo-second-order equation,while the NH4(+) release fitted this model when Cd2+ concentrations were 1, 5, 10 mg x L(-1). The gradual decrease of pH during adsorption of Cd2+ by Alfalfa was observed. As the competition ion of Cd2+, H+ might affect the capacity of Alfalfa root system to absorb Cd2+. The ternary linear equation results demonstrated that the content of Cd2+ absorption by Alfalfa strongly related with the release of Ca2+, Mg2+, Na+. And this exchange mainly occurred among Cd2+ and divalent cations.

The biodegradation of triphenyltin (TPT) by Rhodopseudomonos spheroids was investigated in this study. The results illuminated that R. spheroids was an effective strain for the biodegradation of TPT. The maximum removal ratio was attained when the growth temperature of R. spheroids was 30 degrees C. After treating for 3 hours, the removal ratios of 3 mg x L(-1) TPT were 13.82% to 47.29% using 0.49 g x L(-1) (based on dry weight) biomass of R. spheroids. The experiments on biodegradation of TPT were carried out in double-distilled water, simulated seawater,culture medium and river water, respectively. The results demonstrated that river water was optimal for the biodegradation since the indigenous microorganisms in water synergistically increased the removal ratios of TPT. Extracellular enzyme produced by R. spheroids was also effective on the degradation of TPT, and 71.64% of TPT was degraded by this way within 24 hours. The experiments also revealed that the biodegradation process of TPT included biosorption by cell wall, TPT entering cells, and initial degradation by intracellular enzyme, then the TPT and intermediate products backing out of cells to be degraded by extracellular enzyme.

The objective of this study is to illuminate the mechanism of biodegradation of triphenyltin (TPhT). The removal of TPhT by Klebsiella pneumoniae was, therefore, investigated through characteristics studies. The influences of the various parameters were also discussed. The results demonstrated that the cell, extracellular secretion and intracellular enzyme were the effective biomasses for the biodegradation of TPhT. At initial concentration of 3 mg x L(-1), 10.9%, 5.3% and 47.9% of TPhT could be degraded by these biomasses respectively at 30 degrees C within 2 hours under an rotary shaker at 120 r x min(-1). The experimental results also showed that the enzyme activity could be affected by the buffers, pH, temperature, metals and the concentration of TPhT. The degradation efficiency would reach the highest point at pH 8, and at the optimal temperature of 50 degrees C. Metals including Mg2+, Mn2+, Fe2+ and Fe3+ improved the enzyme activity at certain concentrations. In the presence of 15 mg x L(-1) of Mg2+, the removal percentage of TPhT was up to 73.8%. It suggested that the metals activated the enzyme and interacted with the TPhT enabling its removal during the biodegradation process. Linear plots of removal ratios versus concentrations of TPhT meant that the biodegradation fitted the Michaelis-Menten model. The Vmax and Km of this biodegradation were 0. 15 mg x (L x min)(-1) and 47.1 mg x L(-1), respectively.

The biosorption and biodegradation of triphenyltin (TPhT) from aqueous solutions by isolated strains were investigated through microbial separation and characteristic studies. The results illuminated that Klebsiella pneumoniae was an effective strain for the biosorption and removal of TPhT. 70% to 97.9% of TPhT with initial concentration of 3 mg x L(-1) could be absorbed within 2 h, and 26.4% to 54.6% of this TPhT was biodegraded within 5 d using 0.3 g x L(-1) to 3.0 g x L(-1) biomass of K. pneumoniae. TPhT could be more effectively degraded by separated endoenzyme than by cell biomass,and 28.1% to 77.8% of TPhT would be degraded by this way within 2.0 h.The biodegradation experiments also showed that the degradation of TPhT by K. pneumoniae mainly occurred intracellularly and the increase of degradation rate gradually slowed down with time. Separated endoenzyme gave rise to the highest biodegradation of TPhT at the contact time of 2.0 h,while the intact cell achieved the highest rate of biodegradation within 1 d, and then reached a plateau among 2 d to 5 d. The experiments also revealed that the biodegradation process of TPhT included biosorption by cell wall, active transportation across cell membrane, and biodegradation within cytoplasm, in which TPhT bio-adsorbed oh the cell wall increased linearly with time,TPhT inside the cell wall decreased rapidly from 55.9% to 17.0% during the first 3 d, and then turned to smooth; while TPhT in the supernate changed reversely with that occurred inside the cell wall.

An anthracene-degrading strain (A10) was isolated from contaminated environment and identified as Aspergillus fumigatus. The experimental results showed that the biodegradation rate of anthracene increased with the increasing time. Between 12-84 h interval, the biodegradation performed rapidly, while after this, the increase of biodegradation rate tended to become slow, and ultimately the biodegradation rate could achieve approximately 83%. The degradatinn rate of anthracene reached 79.37% within 5 days when the initial concentration of anthracene in mineral salts medium (MSM) was 10 mg/L, the inoculum dosage was 50 g/L (wet weight) and the cell age was 36 h. The concentration of anthracene had notable influence on degradation function of strain A10 and the highest degradation rate (92.17%) was achieved when anthracene concentration was 5 mg/L. The degradation rate could maintain about 60% with initial pH of MSM in the range of 5.0-7.5, and also, the anthracene could be better broken down when the temperature was 30 degrees C and dissolved oxygen was 4.30 mg/L. Certain amount of nutrition salts promoted the biodegradation of anthracene to some extent. Addition of lactose as co-metabolic substrate most favorably accelerated degradation of anthracene by about 37.15%. The mechanism research revealed that the biodegradation by strain A10 was a dynamic process in which extracellular sorption and intracellular degradation were included. FT-IR analysis exhibited that the structure of anthracene changed with the action of microbe, generating a series of metabolites, such as aromatic acid, aromatic ketone, aromatic aldehyde with one or two benzene rings, as well as saturated hydrocarbons.

In view of joint contamination of heavy metals and polybrominated diphenyl ethers (PBDEs) caused by electronic-wastes, analysis measures of GC-MS, ICP, UV scanning, fTIR, SEM, etc. were used to research on the debromination of deca-brominated diphenyl ethers (BDE209) and biodegradation capability under aerobic condition by combined Bacillus cereus XPB and XPC, and the effects of low concentrations of heavy metals on the biodegradation of BDE209 were also studied. The experimental results showed that combined Bacillus cereus efficiently debrominated and degraded BDE209 to hydroxybenzenes, and the highest debromination capability of 1.18 mg x L(-1) with the efficiency of 14.16% at least was achieved after 1 d reaction. Although biodegradation process was delayed at presence of low concentrations of heavy metals, satisfying degradation effect was still achieved with debromination efficiency of not less than 13.92%. Hydroxy, a minoacyl, and alkyl were confirmed to be the key functional groups for combined Bacillus cereus to biodegrade BDE209 and adsorb heavy metals. Obvious release of K+ and Na+ was observed and the release quantity rose up from 148.867 micromol x g(-1) and 225.835 micromol x g(-1) respectively, when only biodegradation was involved, to 156.482 micromol x g(-1) and 261.217 micromol x g(-1) individually when biodegradation and biosorption acted simultaneously. During the process of BDE209 biodegradation, the highest adsorption rates for Pb2+, Zn2+, and Cu2+ by combined Bacillus cereus were 89.47%, 72.22% and 39.83% respectively.

The biodegradation characteristics of a typical polycyclic aromatic hydrocarbon, naphthalene by the strain (Pseudomonas sp. N7) were investigated by using HPLC and UV analytical techniques. The results showed that the addition of nutritious salt and microelements accelerated the degradation of naphthalene by 23.65%. Degradation efficiency increased with increasing dissolved oxygen and reached 95.66%, then remained stabilized when dissolved oxygen was over 4.3 mg/L, yet decreased with increasing naphthalene concentration. Neutral and weak alkaline condition favored the biodegradation with degradation capacity all over 82.88%. Pseudomonas sp. N7 had a maximum degradation capability of 95.66% when dealing with 100 mg/L naphthalene at 30 degrees C and pH 7.5 with 165 r/min rotary shaking for 72 h. By measuring the absorbance, pH and degradation of substrates during treatment of different substrate with strain N7, it was demonstrated that Pseudomonas sp. N7 could also degrade other aromatic hydrocarbons, such as toluene, dimethylbenzene, phenol, 2,4-nitrophenols, benzyl acid, 1-naphthol and salicylic acid, utilizing each of them as sole carbon and energy source for growth and breeding, thus showing its good biodegradation diversity. The pathway of naphthalene degradation was explored through analyzing metabolic intermediates at different degradation stages by using UV-Vis and GC-MS. The result revealed that there were two possible degradation pathways for naphthalene: one was phthalic acid pathway, and the other was that naphthalene was first oxidized to 1,2-dihydroxynaphthalene, and then the cleavage of rings caused the formation of salicylic acid, catechol, and 2-hydroxymuconic semial-dehyde. Finally these metabolites entered the tricarboxylic acid cycle (TCA).

Ultraviolet and HNO2 were selected as the mutagens to perform the single factor and multi-factor induction mutation towards Candida utilis CR-001. Six mutant strains which possessed high heavy metal removal efficiency and high resistance to Cr6+ were obtained through combined induction with UV and HNO2. After they were subcultured for 10 generations, the diameter of bacteriostatic circle of CRC2811-1 and CRC7-2 was reduced to 1.7 mm and 1.2 mm respectively, while the Cr6+ removal efficiency of CRC2811-1 was increased from 80.2% to 95.2%, and that of CRC7-2 was from 81.2% to 94.7%. The stability of the other 4 mutant strains was rather stable. Furthermore, precipitation of chromium outside or inside the cell was studied by using combined technique of scanning electron microscopy(SEM), transmission electron microscopy (TEM), and atomic force microscopy(AFM), and the mechanism of chromium removal improvement by the mutant strains was discussed.