摘要:

Hydrocarbon‐degrading bacteria in freshly collected petroleum‐rich Guaymas Basin sediments were enumerated on mineral base media separately containing naphthalene, biphenyl, or the aromatic carboxylic acids benzoate, p‐hydroxy‐benzoate, mandelate, salicylate, phenylacetate, phthalate, or hydrocinnamate. The total numbers of bacteria were about 2 orders of magnitude higher on the carboxylic acid media than on the two aromatic hydrocarbons, averaging 105versus 103bacteria per gram of sediment. Of 151 isolates of aerobic, mesophilic marine bacteria, 124 grew exclusively on one or more of the aromatic carboxylic acids. The remaining 27 isolates used either naphthalene, biphenyl, dibenzofuran, toluene, or phenanthrene and various combinations of aromatic carboxylic acids. A similarity analysis of 135 of the isolates on the basis of substrate use, sodium chloride requirement, and growth on complex organic marine media identified 91 metabolically different bacterial strains: 21 belonging to the group of aromatic hydrocarbon utilizers and 70 to the group of carboxylic acid utilizers. Since compounds utilized by organisms of the first group represent end products of petroleum catagenesis, we expected these organisms to predominate. Our results indicate, however, that in Guaymas Basin sediments the majority of hydrocarbon‐degrading bacteria, numerically and metabolically, appear to be determined by the presence of significant quantities of aromatic carboxylic acids.

ISSN:0149-0451    

DOI:10.1080/01490459309377928

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The ecological and physiological factors governing microbial activity in the Southeast Vassar Vertz Sand Unit (SEWSU), Payne County, OK, an oil reservoir selected for a microbially enhanced oil recovery field pilot, were studied. Analysis of the brines from the reservoir showed that the SEWSU reservoir is a hypersaline environment rich in calcium and magnesium cations, and contains most of the inorganic nutrients required for microbial growth. Substantial amounts of sulfate and sulfide were detected in the brines, indicating a potential for sulfate reduction activity. Of the various carbohydrate‐based nutrients tested, a molasses‐ammonium nitrate nutrient mixture best stimulated the metabolism and growth of the microbial communities in the brines. Sulfide was not detected in any brine samples that received high levels of nitrate, even when additional carbon sources such as molasses were added. The addition of nitrate also resulted in shorter lag times, higher maximum turbidities, and larger pressure increases due to gas production. Aerobic heterotrophic bacteria, anaerobic heterotrophic bacteria, anaerobic molasses nitrate‐using bacteria, sulfate‐reducing bacteria, and methanogenic bacteria capable of growing at high salt concentrations were detected in all the brines. Several bacterial strains were isolated, five of which were further characterized. All five isolates were strictly anaerobic and obligately halophilic, requiring a minimum of 6–9% NaCl (w/v) for growth in complex medium. Glucose was fermented to HvCO2, ethanol, and acetate by all the five strains. In spite of the high salinity, the SEWSU reservoir contains an active microbial community whose metabolism and growth can be stimulated by the addition of carbohydrate‐based nutrients.

ISSN:0149-0451    

DOI:10.1080/01490459309377929

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Laboratory columns under continuous flow were packed with peat from the catotelm of an ombrotrophic bog to simulate the natural environment. Methane concentration increased from 1.4 to 47.8 μmol ml−1due to anaerobic microbial degradation of the peat, while at the same time the water flow rate decreased from log ‐1.39 to ‐3.03 cm3s−1and the moisture content decreased from 85.7 to 56.6%. A control column sterilized by irradiation produced carbon dioxide, but, as the flow of water washed this soluble gas out of the column, the hydraulic conductivity and moisture content increased. These two results suggest that it is the volume of the gas (in the gas phase within the bog) that controls the hydraulic conductivity of peat bogs. Volume accounting at the end of the experiment showed no gas in the sterilized column but 17% gas by volume in the microbially active column. We suggest that as gas bubbles occlude the interstitial pores of the peat the water flow is impeded, reducing both the hydraulic conductivity and the water saturation. The difficulty experienced in draining peat bogs is due to this occlusion, which is also responsible for the heightened water table found in raised bogs. Although methane is produced in bogs, only very low levels of methane emission have been reported. Thus the methane released from northern areas will only significantly contribute to increasing radiative gases in the atmosphere if the bogs themselves are disturbed, for example by mining, when the entrapped methane is released, the water table falls, and the bog dries out.

ISSN:0149-0451    

DOI:10.1080/01490459309377930

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The potential utility of55Fe as a tracer for Fe(III) reduction in aquatic sediments was evaluated using freshwater sediments from the Potomac River, Md, in which Fe(III) reduction was the predominant terminal electron accepting process. In laboratory incubations of sediments amended with poorly crystalline55Fe(III) oxide, the accumulation of55Fe in Fe(II) over time paralleled Fe(II) production. However, within 1 h of addition of55Fe(III) oxide, significant quantities of55Fe were recovered in extractable (1 M sodium acetate, pH 5) and soluble Fe(II) pools. There was proportionately more55Fe(II) activity in sediments with higher Fe(II) concentrations. These results suggest that there was rapid isotopic exchange between55Fe in poorly crystalline Fe(III) oxide and the Fe(II) pools. Because of this exchange,55Fe could not be used to trace Fe(III) reduction in sediments in the manner that35SO42−is used to trace sulfate reduction. Although accumulation of55Fe in Fe(II) pools paralleled unla‐beled Fe(II) production, given the relative ease with which Fe(II) pools in sediments can be measured there is no apparent advantage to using55Fe to follow Fe(III) reduction.

ISSN:0149-0451    

DOI:10.1080/01490459309377931

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Three different strains ofThiobacillus ferooxidanswere grown in aqueous ferrous sulfate solutions at 30.5°C and at pH 2.0 in a bioreactor. Their specific growth rate followed Monod kinetics. Their maximum specific growth rate (μm)was between 0.138 and 0.148 h−1and their saturation constant (Ks) was in the range from 0.338 to 0.479 g Fe2+/L. Comparing our data with other data from the literature, we concluded that the kinetics of ferrous iron oxidation is independent of the strain used. A good approximation of the growth kinetics on ferrous iron ofThiobacillus ferrooxidansbetween 20 and 32°C and pH 2.0–2.5 is obtained by using μm= 0.14 h−1Ks= 0.4 g Fe2+/L

ISSN:0149-0451    

DOI:10.1080/01490459309377932

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

ISSN:0149-0451    

DOI:10.1080/01490459309377933

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

ISSN:0149-0451    

DOI:10.1080/01490459309377927

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor