خيارات البحث
النتائج 1 - 10 من 17
Fungal hyphae stimulate bacterial degradation of 2,6-dichlorobenzamide (BAM)
2013
Knudsen, Berith Elkær | Ellegaard-Jensen, Lea | Albers, Christian Nyrop | Rosendahl, Søren | Aamand, Jens
Introduction of specific degrading microorganisms into polluted soil or aquifers is a promising remediation technology provided that the organisms survive and spread in the environment. We suggest that consortia, rather than single strains, may be better suited to overcome these challenges.Here we introduced a fungal–bacterial consortium consisting of Mortierella sp. LEJ702 and the 2,6-dichlorobenzamide (BAM)-degrading Aminobacter sp. MSH1 into small sand columns. A more rapid mineralisation of BAM was obtained by the consortium compared to MSH1 alone especially at lower moisture contents. Results from quantitative real-time polymerase chain reaction (qPCR) demonstrated better spreading of Aminobacter when Mortierella was present suggesting that fungal hyphae may stimulate bacterial dispersal. Extraction and analysis of BAM indicated that translocation of the compound was also affected by the fungal hyphae in the sand. This suggests that fungal–bacterial consortia are promising for successful bioremediation of pesticide contamination.
اظهر المزيد [+] اقل [-]Experimental increase in availability of a PAH complex organic contamination from an aged contaminated soil: Consequences on biodegradation
2013
Cébron, Aurélie | Faure, Pierre | Lorgeoux, Catherine | Ouvrard, Stéphanie | Leyval, Corinne
Although high PAH content and detection of PAH-degraders, the PAH biodegradation is limited in aged-contaminated soils due to low PAH availability (i.e., 1%). Here, we tried to experimentally increase the soil PAH availability by keeping both soil properties and contamination composition. Organic extract was first removed and then re-incorporated in the raw soil as fresh contaminants. Though drastic, this procedure only allowed a 6-time increase in the PAH availability suggesting that the organic constituents more than ageing were responsible for low availability. In the re-contaminated soil, the mineralization rate was twice more important, the proportion of 5–6 cycles PAH was higher indicating a preferential degradation of lower molecular weight PAH. The extraction treatment induced bacterial and fungal community structures modifications, Pseudomonas and Fusarium solani species were favoured, and the relative quantity of fungi increased. In re-contaminated soil the percentage of PAH-dioxygenase gene increased, with 10 times more Gram negative representatives.
اظهر المزيد [+] اقل [-]Thorium(IV) removal from aqueous medium by citric acid treated mangrove endophytic fungus Fusarium sp. #ZZF51
2013
Yang, S.K. | Tan, N. | Yan, X.M. | Chen, F. | Long, W. | Lin, Y.C.
Thorium(IV) biosorption is investigated by citric acid treated mangrove endophytic fungus Fussarium sp. #ZZF51 (CA-ZZF51) from South China Sea. The biosorption process was optimized at pH 4.5, equilibrium time 90min, initial thorium(IV) concentration 50mgL−1 and adsorbent dose 0.6gL−1 with 90.87% of removal efficiency and 75.47mgg−1 of adsorption capacity, which is obviously greater than that (11.35mgg−1) of the untreated fungus Fussarium sp. #ZZF51 for thorium(IV) biosorption under the condition of optimization. The experimental data are analyzed by using isotherm and kinetic models. Kinetic data follow the pseudo-second-order model and equilibrium data agree very well with the Langmuir model. In addition, FTIR analysis indicates that hydroxyl, amino, and carbonyl groups act as the important roles in the adsorption process.
اظهر المزيد [+] اقل [-]Natural antifouling compounds produced by a novel fungus Aureobasidium pullulans HN isolated from marine biofilm
2013
Gao, Min | Su, Rongguo | Wang, Ke | Li, Xuzhao | Lu, Wei
A fungus, Aureobasidium pullulans, was isolated from marine biofilm and identified. A bioassay-guided fractionation procedure was developed to isolate and purify antifouling compounds from A. pullulans HN. The procedure was: fermentation broth—aeration and addition of sodium thiosulfate–graduated pH and liquid–liquid extraction—SPE purification—GC–MS analysis. Firstly, the fermentation broth was tested for its toxicity. Then it was treated with aeration and addition of sodium thiosulfate, and its toxicity was almost not changed. Lastly, antifouling compounds were extracted at different pH, the extract had high toxicity at pH 2 but almost no toxicity at pH 10, which suggested the toxicants should be fatty acids. The EC50 of the extract against Skeletonema costatum was 90.9μgml−1, and its LC50 against Balanus amphitrete larvae was 22.2μgml−1. After purified by HLB SPE column, the EC50 of the extract against S. costatum was 49.4μgml−1. The myristic and palmitic acids were found as the main toxicants by GC–MS.
اظهر المزيد [+] اقل [-]Toxicity of Epoxiconazole to the Marine Diatom Chaetoceros calcitrans: Influence of Growth Conditions and Algal Development Stage
2013
Amara, Anis | Quiniou, Franc̦oise | Durand, Gaël | El Bour, Monia | Boudabous, Abdellatif | Hourmant, Annick
The triazole fungicide epoxiconazole is extensively used to control fungi on crops and may present some potential risk from runoff on coastal ecosystems located close to agricultural areas. Phytotoxicity assessments were conducted on the marine diatom Chaetoceros calcitrans using both the active ingredient and its formulated product (Opus). The 3-day EC₅₀ using cell count was 2.31 mg/L for epoxiconazole active ingredient and 2.9 μg/L for epoxiconazole-formulated. The fungicide produced an increase of cellular volume, pigment (chlorophylls a, c, and carotenoids) content, ATP synthesis, and rates of photosynthesis and respiration. Progressive algal cell recovery from epoxiconazole effects occurred after 3 days, with the increasing cell density. Differences in cell age, light, and nutrient composition induced changes in epoxiconazole sensitivity. Since these parameters affect cellular division rates, the cellular density is an important parameter in toxicity tests.
اظهر المزيد [+] اقل [-]Tolerance of Selected Plant Species to Petrogenic Hydrocarbons and Effect of Plant Rhizosphere on the Microbial Removal of Hydrocarbons in Contaminated Soil
2013
Shahsavari, Esmaeil | Adetutu, Eric M. | Anderson, Peter A. | Ball, A. S.
In this study, 11 plants (legumes, grasses, and crops) were screened for their ability to grow and survive in soil contaminated with 1 % diesel/oil mix (aliphatic hydrocarbons) or 1 % crude oil. Based on emergence, shoot length, root length, and root/shoot biomass ratio in contaminated soil, maize and wheat which showed the highest growth were selected for further investigation: a long-term phytoremediation study to evaluate the effect of maize and wheat on the microbial removal of hydrocarbons (1 % diesel/oil mix). The results showed that the presence of both maize and wheat in hydrocarbon-contaminated soil led to a significant increase in the utilization of total petroleum hydrocarbon (TPH), from 57 % in the control soil to 72 and 66 % in soil planted with maize and wheat, respectively. Microbial community analysis using denaturing gradient gel electrophoresis (DGGE) showed that the presence of a plant rhizosphere resulted in changes in the structure of the soil microbial community. Sequencing of prominent bands revealed the presence of a few hydrocarbonoclastic fungi only in the contaminated soil planted with maize and wheat. In terms of specific hydrocarbonoclastic activity, DGGE analysis based on alkB genes showed that soils with maize and wheat had similar rates of hydrocarbonoclastic activity but distinct microbial communities in some instances. Most probable number quantitative polymerase chain reaction (MPN-qPCR) confirmed that the number of alkB gene copies in soil planted with maize and wheat increased about 20- and 16-fold, respectively, relative to the control soil. This study showed that fungal and alkB bacterial communities contribute to the rhizoremediation of petrogenic hydrocarbons.
اظهر المزيد [+] اقل [-]Biotreatment of Melanoidin-Containing Distillery Spent Wash Effluent by Free and Immobilized Aspergillus oryzae MTCC 7691
2013
Chavan, M. N. | Dandi, N. D. | Kulkarni, M. V. | Chaudhari, A. B.
A total of three fungal isolates from samples collected at spent wash disposal area were screened for their ability to degrade melanoidin. Distillery molasses spent wash was decolorized, and its chemical oxygen demand (COD) was reduced in immobilized fungal bioreactor (IFB) in the absence of carbon and nitrogen source using fungal mycelia of Aspergillus oryzae MTCC 7691. Fungal mycelia immobilized on baggase packed in a glass column under a batch-wise mode (1) effected removal of 75.71 +/- 0.12 % color, 51.0 +/- 0.13 % biological oxygen demand (BOD), 86.19 +/- 2.56 % COD, and 49.0 +/- 0.12 % phenolic pigments of distillery spent wash up to 25 days at 30 degrees C, while free fungal mycelia resulted in removal of 63.1 +/- 0.16 % color, 27.74 +/- 0.14 % BOD, 76.21 +/- 1.62 % COD, and 37.32 +/- 0.17 % phenolic pigments of distillery spent wash using shake flask, (2) manganese peroxidase (MnP) activity was highest (1.55 +/- 0.01 U ml(-1) min(-1)) in immobilized fungi, followed by lignin peroxidase (0.65 +/- 0.01 U ml(-1) min(-1)) and laccase activity (0.9 +/- 0.01 CU ml (1) min (1)), (3) accumulative MnP activity was highly correlated with (r=0.9216) spent wash decolorization and (r=0.7282) reduction of phenolic pigments, suggesting the presence of MnP activities in bioremediation of spent wash and (4) degradation of spent wash was confirmed by high-performance thin layer chromatography and gas chromatography-mass spectrometry analysis. Measurement of chlorophyll a content of Chlorella species cultivated on treated spent wash effluent obtained from immobilized fungal bioreactor was 5.16 +/- 0.71 mu g ml(-1) compared with 1.306 +/- 0.017 +/-mu g ml(-1) obtained with untreated spent wash. Thus, this work may provide a reasonable alternative for cost-effective bioremediation of distillery spent wash using immobilized A. oryzae on baggase fibers.
اظهر المزيد [+] اقل [-]Sequential treatment of olive oil mill wastewater with adsorption and biological and photo-Fenton oxidation
2013
Aytar, Pınar | Gedikli, Serap | Sam, Mesut | Farizoğlu, Burhanettin | Çabuk, Ahmet
Olive oil mill wastewater (OMWW), a recalcitrant pollutant, has features including high phenolic content and dark color; thereby, several chemical or physical treatments or biological processes were not able to remediate it. In this study, the treatment efficiencies of three treatments, including adsorption, biological application, and photo-Fenton oxidation were sequentially evaluated for OMWW. Adsorption, biological treatment, and photo-Fenton caused decreasing phenolic contents of 48.69 %, 59.40 %, and 95 %, respectively. However, after three sequential treatments were performed, higher reduction percentages in phenolic (total 99 %) and organic contents (90 %) were observed. Although the studied fungus has not induced significant color reduction, photo-Fenton oxidation was considered to be an attractive solution, especially for color reduction. Besides, toxicity of OMWW treatment was significantly reduced.
اظهر المزيد [+] اقل [-]Study of microbes having potentiality for biodegradation of plastics
2013
Ghosh, Swapan Kumar | Pal, Sujoy | Ray, Sumanta
Plastic is a broad name given to the different types of organic polymers having high molecular weight and is commonly derived from different petrochemicals. Plastics are generally not biodegradable or few are degradable but in a very slow rate. Day by day, the global demand of these polymers is sharply increasing; however, considering their abundance and potentiality in causing different environmental hazards, there is a great concern in the possible methods of degradation of plastics. Recently, there have been some debates at the world stage about the potential degradation procedures of these synthetic polymers and microbial degradation has emerged as one of the potential alternative ways of degradation of plastics. Alternatively, some scientists have also reported many adverse effects of these polymers in human health, and thus, there is an immediate need of a potential screening of some potential microbes to degrade these synthetic polymers. In this review, we have taken an attempt to accumulate all information regarding the chemical nature along with some potential microbes and their enzymatic nature of biodegradation of plastics along with some key factors that affect their biodegradability.
اظهر المزيد [+] اقل [-]Ligninase-mediated transformation of 4,4′-dibromodiphenyl ether (BDE 15)
2013
Feng, Yiping | Mao, Liang | Chen, Yijun | Gao, Shixiang
The structurally related hydroxylated polybrominated diphenyl ether (PBDE) like hydroxylated 4,4′-dibromodiphenyl ether widely occur in precipitation, surface water, and biotic media. The origins of hydroxylated PBDEs (OH-PBDEs) are of particular interest due to their greater toxic potencies than the corresponding PBDEs. We studied the transformation behavior and products of 4,4′-dibromodiphenyl ether (BDE 15) mediated by lignin peroxidase (LiP), an extracellular enzyme that is produced by certain white rot fungus and is widely present in the natural environment. We found that BDE 15 can be effectively transformed through the reaction mediated by LiP, and two different mono-OH-dibromodiphenyl ethers were identified by using gas chromatography–mass spectrometry (GC-MS) and GC-MS/MS. In particular, we compared the reaction behavior for systems variously containing natural organic matter (NOM) and/or veratryl alcohol (VA), a metabolite that certain fungus produces along with LiP in nature. It was found that the VA’s enhancement effect on LiP performance was impaired by the presence of NOM. The findings in this study provide useful information for better understanding the origins of OH-PBDEs found in the environment.
اظهر المزيد [+] اقل [-]