Role of diazotrophic bacteria in the bioremediation of crude oil‐polluted soil

Nitrogen is one of the most limiting inorganic nutrients in the process of bioremediation of crude oil‐polluted environments. Enhanced remediation of crude oil polluted soil was achieved, in situ, by accelerating the biodegradation process through seeding with adapted Azotobacter which not only acted as supplier of fixed nitrogen to the indigenous crude oil‐degrading bacteria, but also performed some co‐metabolic activities. This work describes the capability of Azotobacter in providing activities that are useful in the bioremediation of crude oil‐polluted soil and biological nitrogen fixation when in association with indigenous oil‐degrading bacteria. © 1999 Society of Chemical Industry     

Evaluation of Nitrogen Fixing Enzyme Activities in Response to Pyrene Bioremediation Efficacy by Defined Artificial Microalgal-Bacterial Consortium of Gujarat,India

This study was carried out to investigate the response and relationship between nitrogen fixing enzymes during the remediation of different concentrations of high molecular weight four rings Polynuclear Aromatic Hydrocarbon (PAH) Pyrene by microalgae Synechocystis sp. (cyanobacteria) with artificial developed indigenous bacterial consortium. One axenic microalgal culture of Synechocystis sp. and two pyrene degrading indigenous bacteria with efficient removal capabilities viz. Pseudomonas indoxyladons and Bacillus benzoevorans isolated from crude oil polluted site and common industrial effluent canal were used to construct the consortium. The effect of pyrene on algal growth in terms of chlorophyll-a was measured and it was found that in the presence of bacteria, the growth and bioremediation capacity of Synechocystis sp. raised tremendously, whereas Synechocystis sp. monoculture exhibited concentration dependent decrease. Moreover, the nitrogen fixing enzymes; nitrate reductase (NR), glutamine synthetase (GS), and succinate dehydrogenase (SDH) showed chronological decrease by 93%, 90%, and 98%, respectively. Increased Bioremediation of pyrene by consortium JPNKA7B2 (Mix culture of Synechocystis sp., Pseudomonas indoxyladons, and Bacillus benzoevorans) was eliminated at 94.1% in 50 mg/L, which indirectly retarded the nitrogen fixing enzymes – NR, GS, and SDH. However, Synechocystis sp. monoculture could remediate up to 36% at 1.5 mg/L after 16 days of incubation.     

Biodegradation of quinoline in crude oil

Removal of quinoline, which is typical of nitrogen‐containing compounds in crude oil, was achieved by a biodegradation reaction by Comamonas sp TKV3‐2‐1. The aerobic strain, Comamonas sp TKV3‐2‐1, which can grow utilizing quinoline as the sources of both carbon and nitrogen, degraded quinoline to 2‐hydroxyquinoline, finally to water‐soluble substances. The degradation reaction of 2‐hydroxyquinoline was revealed to be regarded as a rate‐limiting step controlling the overall reaction of biodenitrogenation process of quinoline in crude oil. The degradation rate of 2‐hydroxyquinoline in a stirred fermenter had a maximum of 211 mg 2‐hydroxyquinoline g‐cell^?1 h^?1 when the portion of crude oil in the reaction mixture, the cell concentration and the rotational speed of agitation impeller were 83.3%(v/v), 28.5 gdm^?3 and 11.7 s^?1, respectively. After the reaction was completed, the crude oil and the cell suspension could be separated efficiently by centrifuging. The possibility of constructing a bioprocess for removing quinoline in crude oil under storage is also discussed. © 2001 Society of Chemical Industry     

Comparing phenanthrene degradation by alginate‐encapsulated and free Pseudomonas sp. UG14Lr cells in heavy metal contaminated soils

BACKGROUND: Many polycyclic aromatic hydrocarbon (PAH) contaminated sites also contain high levels of toxic heavy metals. The presence of heavy metals can adversely affect PAH biodegradation. Encapsulation of bacterial cells has been shown to improve survival and activity of cells under various environmental stresses. This study examined if encapsulation of a phenanthrene‐mineralizing bacterial strain could improve its survival and phenanthrene degradation in heavy metal contaminated soils. RESULTS: Alginate encapsulation did not improve survival and phenanthrene degradation by Pseudomonas sp. UG14Lr in heavy metal contaminated soil. Phenanthrene degradation by, and survival of, free cells and alginate‐encapsulated cells were similar in soil contaminated with 5 mg kg^?1 dry soil of As, Cd, or Pb. The number of UG14Lr cells decreased to undetectable level when the concentration of each heavy metal was increased to 100 mg kg^?1 dry soil. UG14Lr, when inoculated as free cells, survived the best and they were detected over 60 days of incubation in soil. Cells in both wet and dry alginate beads survived less well than free cells at the higher metal concentrations. Correspondingly, phenanthrene degradation in soil inoculated with free UG14Lr was better than that in soil inoculated with alginate‐encapsulated cells. CONCLUSION: Alginate encapsulation adversely affected the survival and phenanthrene degradation ability of UG14Lr cells in heavy metal contaminated soil. It is postulated that alginate may have concentrated the metals which in turn increased the toxicity to UG14Lr cells. The results are of interest to those interested in the use of encapsulation technology to formulate microbial cells for bioremediation purposes. Copyright © 2009 Society of Chemical Industry     

Effect of mobilizing agents on mycoremediation and impact on the indigenous microbiota

BACKGROUND: Mobilizing agents (MAs) have been suggested to improve the fungal degradation of polycyclic aromatic hydrocarbons (PAHs) in soil. Three different MAs (Tween 20, Tween 80 and soybean oil) were investigated for their ability to stimulate contaminant degradation by either Phlebia sp. DABAC 9 or Allescheriella sp. DABAC1 in a soil spiked with a mixture of PAHs. RESULTS: Phlebia sp. and Allescheriella sp. markedly differed in their growth capabilities under non‐sterile conditions and without MAs (3.0 versus 0.1 µg ergosterol g^?1 soil, respectively). However, soybean oil led to a 35‐fold increase of Allescheriella sp. growth. Contaminant degradations by Phlebia sp. DABAC 9 and Allescheriella sp. DABAC 1 were best supported by soybean oil and Tween 20, respectively. Enumeration of cultivable bacteria and denaturing gradient gel electrophoresis (DGGE) analysis of PCR‐amplified 16S rRNA showed that microbial density and biodiversity were positively affected by the mycoremediation especially with Allescheriella sp., the use of which led to an evident detoxification. CONCLUSIONS: Allescheriella sp. DABAC 1 appears to be a promising strain in the remediation of PAH‐contaminated soils. The different response of the two fungi to MAs addition confirms the stringent need for a preliminary lab‐scale assessment of fungus/MA combinations prior to application. Copyright © 2009 Society of Chemical Industry     

Nutritive value of canola (Brassica napus L.) as affected by plant growth promoting rhizobacteria

Comparative evaluation of plant growth promoting rhizobacteria viz. Azospirillum brasilense, Azotobacter vinelandii Khsr1 and chemical fertilizers was made on growth, protein, and oil yield as well as quality of canola (Brassica napus L.) cv. Rainbow. The A. brasilense and A. vinelandii were applied as seed inoculation at 10⁶ cells/mL. The recommended doses of urea (150 kg/ha) and diamonium phosphate (180 kg/ha) were applied as sources of chemical fertilizers. First dose of chemical fertilizers was applied at the time of sowing while other three doses were applied at 45 days interval. The chemical fertilizers were highly effective in increasing leaf chlorophyll content, number of branches per plant, number of siliqua per branch, number of seeds per siliqua, and total seed yield. A. brasilense treatment increased the leaf and seed protein content (32 and 21%) as well as seed size as measured by % increase in 1000 seed weight. A. vinelandii treatment resulted in significant increase (4%) in seed oil contents but the glucosinolate and erucic acid (C22:1) contents of oil was decreased significantly. Maximum oleic acid (C18:1) content was found in seed oil of A. vinelandii treatment; whereas, significantly higher linolenic acid (C18:3) content was recorded in A. brasilense treatment. It is inferred from the present investigation that A. brasilense and A. vinelandii could be highly effective in improving yield and nutritive value of canola oil.     

Reaction Engineering Studies on the Biodegradation of Anthracene on Bioremediation of Diesel Contaminated Soil Using Acinetobacter sp. (ATCC No. 14293)

In the present investigation bio‐degradation of anthracene, a polyaromatic hydrocarbon, from its simulated mixture in methanol, has been studied using a monoculture strain, (Acinetobacter sp. (ATCC No. 14293)), within the concentration range 500‐800 mg/dm³. In a separate attempt bioremediation of diesel contaminated soil to reduce total aromatic content using the same bacterial strain has been carried out. The main emphasis of this investigation is to understand the complex reaction engineering behaviour involved in both the above bioprocess systems. It is observed that while Monod's classical substrate uninhibited model can be used for simulation purpose for the biodegradation of anthracene, the reaction engineering behaviour of the bioremediation of soil can be expressed by coupling Monod's classical equation with first order cell decay rate. In both the cases the concerned intrinsic kinetic parameters have been evaluated.     

Interactions between an alga and three bacterial species in a consortium selected for photosynthetic biomass and starch production

A four-membered consortium (MA003) of an algal species and bacteria was selected from a natural source for its ability to grow at 37°C and produce starch photosynthetically from carbon dioxide. The photosynthetic culture consisted of a Chlorella-like green alga (A003) and three heterotrophic bacteria, Alcaligenes sp. (B001), Flavobacter sp. (B002) and Serratia sp. (B003). The substrates for the bacterial growth were probably organic nitrogen and carbon compounds excreted by the alga at specific rates which were independent of the algal specific growth rate. The maximum specific growth rate of the alga was decreased by an inhibitor produced by bacterium B002. Bacterium B001 removed the inhibitor of algal growth released by bacterium B002, and bacterium B003 decreased the growth of bacterium B002 and consequently the production of algal growth inhibitor. The growth of bacterium B003 was greatly suppressed in the four-member consortium MA003. The coexisting bacteria in toto, did not affect the growth rate, yield and starch production of the algal member, but did help to establish a stable ecosystem and increase the biomass available. A culture density up to 36 g dry weight dm^?3 was achieved without significant variation in the ratio of the species in the culture.     

Effects of nitrogen sources on toluene degradation by Pseudomonas putida BZ918

For effective toluene degradation, the effects of a nitrogen source were studied with Pseudomonas putida BZ912, which was isolated from crude oil contaminated soil and is capable of degrading VOC. Two nitrogen sources, ammonia and nitrate, showed different effects on specific growth rates (0.25 hr⁻¹ and 0.12 hr⁻¹, respectively), biomass yields (0.56 vs. 0.39) and specific toluene degradation rates (0.51 hr⁻¹ vs. 0.26 hr⁻¹). Under the resting cell conditions, the cells pre-cultured in the ammonia-containing medium showed higher specific toluene degradation rate than that in nitrate-containing medium (0.045 hr⁻¹ vs. 0.038 hr⁻¹). Ammonia as a nitrogen source was effective for degradation in high toluene concentration because high cellular biomass was accomplished. Nitrate showed slow growth rate compared to ammonia. The resting cell conditions demonstrated that it was able to degrade toluene efficiently without increasing biomass. These conditions could be a solution for degrading VOC after high cellular biomass was obtained in a biofilter. By changing the nitrogen source and the growth conditions according to the toluene concentration, the control of cell biomass and the desired removal capacity were accomplished.     

Characterization of Biosurfactant Produced by a Novel Strain of Pseudomonas aeruginosa,Isolate ADMT1

Several biosurfactant‐producing bacterial strains were isolated from petroleum‐contaminated soil. The isolate ADMT1, identified as a new strain of Pseudomonas aeruginosa, was selected for further studies on the basis of oil displacement test and emulsification index (E24). The optimal parameters for production, determined by employing Box–Behnken design, were temperature 36.5 °C and pH 7. The environmental isolate ADMT1 produced significant amount of biosurfactant (1.7 g L^?1 in 72 h) in minimal salt medium (MSM) using dextrose as the sole carbon source. The E24 value and critical micelle concentration (CMC) of the biosurfactant was 100% and 150 mg L^?1, respectively. At CMC, the surface tension of water was reduced to 28.4 mN m^?1. The biosurfactant exhibited hemolytic activity and antibacterial activity against 8 reference strains of pathogenic bacteria, including 2 methicillin‐resistant Staphylococcus aureus strains (MRSA ATCC 562 and MRSA ATCC 43300), with minimum inhibitory concentration (MIC) of 0.4 and 0.2 mg mL^?1, respectively. The structure of biosurfactant was characterized by FTIR, ¹H, and ¹³C NMR spectroscopy. 7 di‐rhamnolipid (RL) congeners were identified in the biosurfactant by ultraperformance liquid chromatography–mass spectrometry analysis. The major congeners, which constituted 67% of the RL mixture, included Rha‐Rha‐C₁₀‐C₁₀, Rha‐Rha‐C₁₂‐C₁₀, and Rha‐Rha‐C_12:1‐C₁₀. The minor congeners were Rha‐Rha‐C₁₀‐C₈, Rha‐Rha‐C_10:1‐C₁₀, Rha‐Rha‐C₁₀‐C_14:1, and Rha‐Rha‐C₁₀‐C₁₄. The congener Rha‐Rha‐C₁₀‐C₁₄ is being reported for the first time from any species of Pseudomonas. The high surface activity and E24 value make the ADMT1‐RL a potential candidate for its use in detergents, environmental bioremediation, and as an emulsifier in the food industry.     

Use of biosurfactant in the removal of oil from contaminated sandy soil

The effectiveness of cell‐free rhamnolipid biosurfactant, derived from the culture medium at the end of fermentation was investigated for the removal of two different kinds of oil from contaminated sandy soils. The crude cultivation medium, containing 13.2 g L^?1 of rhamnolipids, had a surface tension, interfacial tension and critical micellar concentration of 30 mN m^?1, 2 mN m^?1 and 60 mg L^?1, respectively. The evaluation of biosurfactant in the culture medium (BM) and oil concentrations in the removal of oil from different contaminated sandy soil was performed using a statistical experimental design tool. Oil in sandy soil, containing predominantly aromatic or paraffinic hydrocarbons (5 to 10% w/w), was removed by as much as 91 and 78%, respectively, in the presence of reduced amounts of BM (6.3 to 7.9 g L^?1). The progress of oil removal was monitored for 101 days and results indicated that removal efficiency in sandy soil with aromatic characteristics was relatively stable over the entire period. Based on these studies, it is concluded that use of a BM was effective in reducing oil concentrations in contaminated sandy soil. Copyright © 2007 Society of Chemical Industry     

Biological treatment of high salinity produced water by microbial consortia in a batch stirred tank reactor: Modelling and kinetics study

This study was performed to evaluate the potential of acclimated halophilic microorganisms, commercial microorganisms, and microorganisms from polluted soil to degrade crude oil in high salinity oily wastewater (synthetic produced water) at different salt concentrations ranging from zero to 250,000?mg?L^?1 of total dissolved solids (TDS). The highest degradation of crude oil (>60%) was found for acclimated halophilic microorganisms at TDS of 35,000?mg?L^?1. An increase in the TDS concentrations above 145,000?mg?L^?1 leads to a significant decrease in the growth of microorganisms. The results showed that efficiency of the commercial microorganisms was less than the acclimated halophilic microorganisms. The oil biodegradation followed substrate inhibition kinetics and the specific growth rate were fitted to the Haldane model. The biokinetic constants for the saline oily water at TDS of 35,000?mg?L^?1, i.e., Y, K_s, µ_max, and 1/K_i, were 0.21?mg?MLSS/mg crude oil, 0.27?mg?L^?1, 0.019?h^?1, and 0.002?mg?L^?1, respectively.     

Synthesis of 2‐monoglycerides by alcoholysis of palm oil and tuna oil using immobilized lipases

Commercial immobilized lipases were used for the synthesis of 2‐monoglycerides (2‐MG) by alcoholysis of palm and tuna oils with ethanol in organic solvents. Several parameters were studied, i.e., the type of immobilized lipases, water activity, type of solvents and temperatures. The optimum conditions for alcoholysis of tuna oil were at a water activity of 0.43 and a temperature of 60 °C in methyl‐tert‐butyl ether for ～12 h. Although immobilized lipase preparations from Pseudomonas sp. and Candida antarctica fraction B are not 1, 3‐regiospecific enzymes, they were considered to be more suitable for the production of 2‐MG by the alcoholysis of tuna oil than the 1, 3‐regiospecific lipases (Lipozyme RM IM from Rhizomucor miehei and lipase D from Rhizopus delemar). With Pseudomonas sp. lipase a yield of up to 81% 2‐MG containing 80% PUFA (poly‐unsaturated fatty acids) from tuna oil was achieved. The optimum conditions for alcoholysis of palm oil were similar as these of tuna oil alcoholysis. However, lipase D immobilized on Accurel EP100 was used as catalyst at 40 °C with shorter reaction times (<12 h). This lead to a yield of ～60% 2‐MG containing 55.0‐55.7% oleic acid and 18.7‐21.0% linoleic acid.     

Removal of polycyclic aromatic hydrocarbons from soil using surfactant and the white rot fungus Phanerochaete chrysosporium

The bioremediation of soil contaminated with polycyclic aromatic hydrocarbons (PAH) is often limited by a low bioavailability of the contaminants. Non‐ionic surfactants, such as Tween 80, when above their critical micelle concentration (CMC), can efficiently enhance the bioavailability of PAHs in contaminated soil by increasing solubility and dissolution rates. However, disposing of this micelle‐contaminated spent washwater can be a major problem. The aim of this study was to combine surfactant soil washing techniques using Tween 80 with the versatile lignin‐degrading system of the white rot fungus, Phanerochaete chrysosporium, to bioremediate PAH‐contaminated soil. Approximately 85% (w/w) of a total of nine PAHs in an aged (1 month) contaminated soil (total PAH concentration = 403.61 µg g⁻¹) could be solubilized in a 2.5% (w/v) Tween 80 solution at a soil/water ratio of 1:10. The washwater was then catabolized by a 3‐day‐old culture of P chrysosporium under a stationary condition. The disappearance of most PAHs tested (molecular weight ≥ 178) correlated well with their ionization potentials and 66.4% (w/w) of the total PAHs in washwater with 2.5% (w/v) Tween 80 was catabolized after 11 days of culture. The catabolism was enhanced to 86% (w/w) using a lower concentration of 0.5% (w/v) Tween 80. The initial oxidation rate of total PAHs based on the first 4 days of culture remained almost constant at approximately 1.88 µg cm⁻³day⁻¹ when the Tween 80 concentration in washwater was increased from 0.5% to 2.5% (w/v). The combination of soil washing and white rot fungus catabolization of PAH using 2.5% (w/v) Tween 80 eliminated the total PAH concentration in the contaminated soil by 56.4% (w/w) after 11 days. The results suggest that PAH‐contaminated soil may be cleansed by using a combination of surfactant soil washing and white rot fungus catabolism. © 2000 Society of Chemical Industry     

Biodegradation of diesel oil in a baffled roller bioreactor

BACKGROUND: Ex situ bioremediation is a feasible and economical way to remove petroleum pollutants from contaminated soil or water. A baffled roller bioreactor was shown to be effective for biodegradation of diesel oil as a model petroleum pollutant. Microorganisms enriched from an industrially contaminated soil with heavy hydrocarbons were shown to be the best inoculum source for diesel biodegradation. RESULTS: The baffled roller bioreactor demonstrated better performance than control (roller bioreactor without baffles) or bead mill roller (control bioreactor filled partially with spherical beads) bioreactors. Biodegradation consisted of both fast and slow stages for degradation of light and heavy compounds, respectively. Among the tested temperatures ranging from 15 to 35 °C, room temperature (23 °C) was found to be the optimum temperature for biodegradation. The values of maximum specific growth rate and substrate yield (µ_max and Y_XS) for the indigenous microorganisms in the baffled roller bioreactor at room temperature were found to be 0.72 ± 0.08 h^?1 and (7.0 ± 1.0) × 10⁷ cells mg^?1 diesel, respectively. Biodegradation of diesel concentrations up to 200 g L^?1 was achieved with the highest biodegradation rate of 266 mg L^?1 h^?1 at the highest rotation rate of 45 rpm in the baffled roller bioreactor. CONCLUSION: Using indigenous bacteria enriched from industrial contaminated soil at room temperature, a baffled roller bioreactor is able to biodegrade high diesel oil concentrations at high biodegradation rates. Copyright © 2008 Society of Chemical Industry     

Effect of enzymatic transesterification on the melting points of palm stearin-sunflower oil mixtures

Transesterification with lipases may be used to convert mixtures of fats to plastic fats, making them more suitable for use in edible products. In our study, 1,3-specific (Aspergillus niger, Mucor javanicus, Rhizomucor miehei, Rhizopus javanicus, and Rhizopus niveus) and nonspecific (Pseudomonas sp. and Candida rugosa) lipases were used to transesterify mixtures of palm stearin and sunflower oil (PS-SO) at a 40:60 ratio in a solvent-free medium. The transesterified mixtures of PS-SO were analyzed for their percentage free fatty acids (FFA), degree and rate of transesterification, solid fat content, slip melting point (SMP), and melting characteristics by differential scanning calorimetry. Results indicated that Pseudomonas sp. lipase produced the highest degree (77.3%) and rate (50.0 h⁻¹) of transesterification, followed by R. miehei lipase at 32.7% and 27.1 h⁻¹, respectively. The highest percentage FFA liberated was also in the reaction mixtures catalyzed by Pseudomonas sp. (2.5%) lipase and R. miehei (2.4%). Pseudomonas-catalyzed mixtures produced the biggest drop in SMP (13.5°C) and showed complete melting at below body temperature. All results indicated conversion of the PS-SO mixtures to a more fluid product. The findings also suggest that the specificity of lipases may not play a significant role in lowering the melting point of the PS-SO mixtures.     

响应曲面法优化混合菌HJ8-1降解水中原油污染物

采用响应曲面法优化混合菌HJ8-1修复原油污染水体的条件,以原油浓度、氮浓度、磷浓度和表面活性剂(SDBS)浓度为自变量、原油降解率为因变量,运用Box-Behnken(BB)设计研究了各自变量及其交互作用对水中原油污染物降解效果的影响.以二次多项式回归方程预测模型为基础,得到含油量为2 g·L-1、11g·L-1和2...     

Petroleum‐contaminated soil remediation in a new solid phase bioreactor

BACKGROUND: Oil spills are a frequent source of environmental contamination. As a consequence, remediation of soils, waters and sediments is a great challenge in this area of research. This study aims at using a new type of soil bioreactor (13 L bench‐scale and 800 L pilot‐scale) to treat tropical soil contaminated with petroleum. Additionally, it includes the evaluation of the effectiveness of two auxiliary techniques: bulking agent addition (sawdust) and biostimulation using two different nitrogen sources (sodium nitrate and urea). RESULTS: The best result in bench‐ and pilot‐scale bioreactors were reached when using urea as a nitrogen supplement and bulking agent addition. Removal of 20 to 35% of total petroleum hydrocarbon (TPH) was achieved within 42 days. The molecular fingerprinting performed with 16S‐PCR analysis associated with denaturing gradient gel electrophoresis (DGGE) was used to evaluate changes in the pattern of the bacterial community for all experimental conditions tested. The results revealed that the use of urea caused a smaller change in the dominant bacterial community structure than the treatments using nitrate, showing that this analysis can be a useful complementary tool to evaluate the impact of treatment strategies applied to hydrocarbon‐contaminated soil. CONCLUSIONS: These new solid phase bioreactors showed satisfactory results in the tropical soil bioremediation process, proving that the homogenization system interferes with crude oil biodegradation efficiency. This new technology can be used as an isolated treatment as well as in association with other classically employed bioremediation technologies. Copyright © 2010 Society of Chemical Industry     

Production of surface-active sophorolipid biosurfactant and crude oil degradability by novel Rhodotorula mucilaginosa strain SKF2

Biosurfactants are produced by important types of microorganisms such as bacteria, yeast, and filamentous fungi and have been used in a variety of industries. Among the 15 crude oil-degrading fungi, the two molds and one yeast were identified by 18S rDNA sequences as Mucor circinelloides strain SKMC, Fusarium fujikuroi strain DB2, and Rhodotorula mucilaginosa strain SKF2. These strains were isolated from crude oil–contaminated soil, diesel oil–contaminated soil, and activated sludge in the Oil Refinery Plant in Isfahan, Iran, respectively. The yeast strain was identified as a novel crude oil–degrading and biosurfactant-producing fungi in the presence of (1% v/v) Iranian light crude oil in the minimal salt medium (MSM). The highest amount of the dry weight of produced biosurfactant was measured at 6.2 g L⁻¹. Chemical nature of produced biosurfactant was determined as a surface-active sophorolipid biosurfactant compound by thin-layer chromatography, Fourier transform infra-red spectroscopy, and gas chromatography–mass spectrometry (GC–MS) analysis. The residual hydrocarbons in the MSM were analyzed by GC–MS, and it was shown that octadecane and docosane were eliminated by this novel strain completely.     

Biodegradation of High Molecular Weight Polycyclic Aromatic Hydrocarbons Mixture by a Newly Isolated Fusarium sp. and Co-Metabolic Degradation with Starch

One native fungal strain, designated ZH-H2, was isolated from an agricultural soil contaminated by HMW-PAHs in a typical coal mining area of Hebei, China. The filamentous fungus was identified as a Fusarium sp. ZH-H2 was able to survive not only in the presence of the individual HMW-PAHs of Chry, BaA, B(K)F, BaP, DB(a,h)A, InP, InP and B(g,h,i)p but in the presence of a mixture of the above seven HMW-PAHs with a total concentration of up to 10 mg L^?1. Biodegradation experiments demonstrated that Fusarium sp. (ZH-H2) was able to degrade the aforementioned individual HMW-PAHs, with a degradation percentage of 77%, 85%, 91%, 42%, 56%, 42% and 38%, respectively, and degrade the aforementioned seven PAHs mixture with a degradation percentage of 48%. The effect of starch addition on the biodegradation efficiency of the PAH mixture was also investigated. The results showed a significant improvement in the degradation extent of the PAH mixture with the increase of starch concentration. The greatest degradation rate (DR; 89%) in 7 d was obtained when starch was added at 1.0 g L^?1, about 2-fold than was achieved without starch. This study implicates that Fusarium sp. (ZH-H2), a potential biodegrader, is suitable for practical field application in effective bioremediation of soils that have been simultaneously contaminated by several HMW-PAHs for a long time.