摘要:

Liquid chromatography/electrospray ionization/mass spectrometry (LC/ESI/MS) was used to determine intact phospholipid profiles for five reference pseudomonad strains harboring different (aerobic) toluene catabolic pathways:Pseudomonas putidamt-2,Pseudomonas putidaF1,Burkholderia cepaciaG4,Burkholderia pickettiiPKO1, andPseudomonas mendocinaKR1. These five strains contained a predominant pool of phosphatidylethanolamines. Other phospholipids identified include phosphatidylglycerol, phosphatidylserine, phosphatidylmethylethanolamine, and phosphatidyldimethylethanolamine. There was a clear separation in phospholipid profiles that allows for the differentiation between thePseudomonasandBurkholderiagenera. Factor analysis of the phospholipid profiles showed thatB. cepaciaG4,P. putidamt-2, andB. pickettiiPKO1 were clearly separated, whileP. putidaF1 andP. mendocinaKR1 were clustered as a group. These results suggest that intact phospholipid profiling could be used to evaluate the relative abundance of specific degraders in bioreactors or in aquifer material. Nevertheless, the usefulness of this technique for taxonomic characterization of such complex samples remains to be demonstrated because of potential confounding effects of overlapping profiles and potential changes in phospholipid composition due to different growth conditions.

ISSN:1088-9868    

DOI:10.1080/10588330008951108

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Assessing petroleum biodegradation rates is an important part of predicting natural attenuation in subsurface sediments. Monitoring carbon dioxide (CO2) and methane (CH4) produced in situ, and their radiocarbon14C), stable carbon (13C) and deuterium (D). signature provide a novel method to assess anaerobic microbial processes. Our objectives were to: (1) estimate the rate of anaerobic petroleum hydrocarbon (PH) mineralization by monitoring the production of soil gas CH4and CO2in the vadose zone of low-permeability sediment, (2) evaluate the dominant microbial processes using δ13C and δD, and (3) determine the proportion of CH4and CO2attributable to anaerobic mineralization of PH using14C analysis. Argon was sparged into the subsurface to dilute existing CO2and CH4concentrations. Vadose zone CO2, CH4, oxygen, total combustible hydrocarbons, and argon concentrations were measured for 75 days. CO2and CH4samples were collected on day 86 and analyzed for14C, δ13C, and δD. Based on CH4soil gas production, the anaerobic biodegradation rate was estimated between 0.017 to 0.055 mg/kg soil-d. CH414C (2.6 pMC), δ13C (-45.64‰), and δD (-316‰) values indicated that fermentation of PH was the sale source of CH4in the vadose zone. CO214C (62 pMC) indicated that approximately 47% of the total CO2was from PH mineralization and 53% from plant root respiration. Although low-permeability sediment increases the difficulty of completely replacing in situ soil gas and assuring anaerobic conditions, this novel respiration method distinguished between anaerobic processes responsible for PH degradation.

ISSN:1088-9868    

DOI:10.1080/10588330008951109

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

In 1996, a controlled crude oil application was conducted at a Texas intertidal, coastal wetland to determine the effectiveness of two biostimulation treatments in these sensitive areas. An inorganic nutrient treatment and inorganic nutrient plus a potential electron acceptor (nitrate) treatment were examined. As part of this research, polycyclic aromatic hydrocarbon (PAH)-degrading, aliphatic-degrading, and total heterotrophic microbial numbers were monitored. Using a randomized, complete block design consisting of 21 plots, microbial data from biostimulation treatment plots were statistically compared to oiled control plots to assess treatment differences. Sediment samples from all plots receiving oil showed exponential increases in the numbers of aliphatic (n-alkane) and PAH-degrading microorganisms. This increase was observed at both 0 to 5 cm and 5 to 10 cm sample depths. Statistical analysis, however, revealed no significant differences in the numbers of aliphatic-degrading or PAH-degrading microorganisms between treatment plots and oiled control plots or between treatments on any sample day. The numbers of PAH- and aliphatic-degrading microorganisms returned to near pre-application levels by the end of the monitoring period. Ratios of hydrocarbon-degrading microbes to total heterotrophs also increased as a result of the oil application and returned to pre-application levels by the end of the monitoring period. Overall, the populations of hydrocarbon-degrading microorganisms illustrated a well-documented response to crude oil. However, the addition of the biostimulation treatments did not significantly increase the numbers of aliphatic-degrading, PAH-degrading, or total heterotrophic microorganisms over populations on control plots.

ISSN:1088-9868    

DOI:10.1080/10588330008951110

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Research was conducted to determine the effect of chemical oxidation on subsurface microbiology and cometabolic biodegradation capacity in a trichloroethene (TCE)/perchloroethene (PCE)-contaminated aquifer previously treated with Fenton's reagent. Groundwater pH declined from 5 to 2.4 immediately after the treatment, and subsequently rose to a range of 3.4 to 4.0 after 17 months. Limited microbial growth and TCE degradation were detected in the treated zone (pH 3.37 and TCE 5 to 21 mg/L) with carbon addition (i.e., methane and phenol). Methane addition resulted in the enrichment of yeast and fungi in microcosms at low pH. In contrast, methane addition to groundwater from the control well (pH 4.9 and TCE ca. 0.7 mg/L) stimulated methanotrophic growth, indicated by methane consumption, fluorescent antibody analysis, phospholipid-based markers, and rDNA probes. TCE degradation was measured in the control microcosms, but only when phenol was added. Although higher TCE concentrations in the treated zone might have inhibited TCE cometabolism, these results also indicate that low groundwater pH resulting from the chemical oxidation process (pH 3.37 versus 4.9) inhibited TCE degradation. Methanotrophic growth and TCE biodegradation may be possible as pH increases both in the treated zone and at the leading edge of plume, as long as the local soil is able to buffer the groundwater pH. Moreover, the Fenton's reagent process could be designed to operate at a higher pH (e.g., ≥ 4.5) and/or lower hydrogen peroxide concentration to minimize detrimental effects, providing an optimal environment to couple advanced oxidation processes with bioremediation technologies.

ISSN:1088-9868    

DOI:10.1080/10588330008951111

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

After the failure of a three-month pump-and-treat exercise to clean up an aquifer contaminated with the pesticides atrazine and fenamiphos, microcosm experiments using14C-labeled compounds were undertaken to determine under what conditions bioremediation would be most effective, and to investigate the prospects for the use of bioaugmentation. The calculated half-lives for atrazine and fenamiphos mineralization to carbon dioxide in unamended, anaerobic aquifer material were 730 and 1,000 years, respectively. Oxygenation, coupled with bioaugmentation with enrichments of atrazine-mineralizing bacteria obtained from the contaminated site or an imported, atrazine-mineralizing pure strain,Pseudomonassp. strain ADP, decreased the half-life of atrazine mineralization, to >20 days. Although strain ADP does not use atrazine as a source of carbon and energy, amendment of the aquifer material with citrate, which strain ADP uses as a source of carbon and energy, did not appreciably stimulate the mineralization rate of atrazine in the microcosms, suggesting that the aquifer contains enough natural organic carbon for atrazine mineralization. Aerobic enrichments of fenamiphos-degrading bacteria were prepared; however, oxygenation and bioaugmentation of aquifer material with these strains did not enhance mineralization of fenamiphos within the time constraints of the experiments. The shortest calculated half-life of fenamiphos mineralization in the microcosms was 6.8 years, which is exceedingly long compared with the half-life of fenamiphos in most surface soils.

ISSN:1088-9868    

DOI:10.1080/10588330008951112

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor