Diesel Oil Concentration Research Articles

Isolation and characterization of marine diesel oil-degrading Acinetobacter sp. strain Y2

The marine diesel oil-degrading bacterium Acinetobacter sp. strain Y2 was isolated from oil-polluted seawater sampled from Dinghai port, Zhoushan City, Zhejiang Province, China. The isolated bacterium was identified as Acinetobacter sp. based on its 16S rDNA gene sequence as well as various morphological and physiological characteristics. The degradation characteristics of strain Y2 were studied and its parameters for oil degradation optimized. These optimal conditions were determined to be an initial pH of 7.5, an incubation temperature of 30 °C, an initial diesel oil concentration of 2 % (v/v), and an initial inoculating bacteria concentration of 3 × 107 cells/mL. The results from the gas chromatography–mass spectrometry analysis showed that strain Y2 could almost completely degrade all components of diesel oil, with a degradation ratio of up to 80 % after 10 days of incubation at the optimal conditions.

Gill histopathological changes in Great sturgeon after exposure to crude and water soluble fraction of diesel oil

This study was conducted to provide baseline data on the gill tissue lesions in Huso huso under exposure to direct and water-soluble fraction of diesel oil. In both condition, histopathological analyses exhibited many gill lesions, including epithelial lifting, erythrocyte infiltration, lamellar aneurism, hyperplasia, and lamellar fusion. We report here the results on several abnormalities in the gill structure of the studied fish under direct and water-soluble fraction of diesel oil concentrations which could be used as biomarkers of diesel oil pollution.

Isolation, identification and biodegradation ability of diesel oil degrading Pseudomonas sp. strain C7 from bilge water.

Some highly efficient diesel oil-degrading bacteria were isolated from bilge water. One isolated strain C7 was identified as Pseudomonas sp. based on its 16S rDNA gene sequence as well as various morphological, physiological and phylogenetic characteristics. The biodegradation potential and characteristics of strain C7 in various conditions were analyzed. GC-MS analysis showed that this strain could degrade most components of diesel oil, and the degradation rate was up to 75.9% after ten days incubation at the optimal condition which included a temperature of 30°C, a pH level of 7.0, initial diesel oil concentrations of 3% (v/v) and initial bacteria concentrations of 4 × 107cells/ml. Key word: Bilge water, biodegradation, diesel oil and Pseudomonas sp.

4种绿化树种盆栽土壤微生物对柴油污染响应及对PAHs的修复

PDF HTML阅读 XML下载 导出引用 引用提醒 4种绿化树种盆栽土壤微生物对柴油污染响应及对PAHs的修复 DOI: 10.5846/stxb201103250383 作者: 作者单位: 南方林业生态应用技术国家工程实验室;中南林业科技大学,中南林业科技大学,湖南会同杉木林生态系统国家野外科学观测研究站;中南林业科技大学,城市森林生态湖南省重点实验室;中南林业科技大学,城市森林生态湖南省重点实验室;中南林业科技大学,城市森林生态湖南省重点实验室;中南林业科技大学,中南林业科技大学 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金资助项目(31070410, 30870455, 30571487, 30771700);教育部新世纪优秀人才支持计划(NCET-10-0151) Remediation of soils contaminated with polycyclic aromatic hydrocarbons (PAHs) using four greening tree species Author: Affiliation: National Engineering Laboratory for Applied Technology of Forestry Ecology in South China,Changsha;Central South University of Forestry and Technology,Central South University of Forestry and Technology,Central South University of Forestry and Technology,Key laboratory of urban forest ecology of Hunan Province;Central South University of Forestry and Technology,Key laboratory of urban forest ecology of Hunan Province;Central South University of Forestry and Technology,Key laboratory of urban forest ecology of Hunan Province;Central South University of Forestry and Technology,Central South University of Forestry and Technology Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:采用室内盆栽实验,利用柴油按不同比例混合土壤0 g/kg(CK),2 g/kg(L1),10 g/kg(L2)和50 g/kg(L3)制备了含不同浓度PAHs的污染土样,选择1年生樟树(Cinnamomum camphora)、广玉兰(Magnolia grandiflora)、栾树(Koelreuteria bipinnata)、马褂木(Liriodendron chinense)幼苗为供试植物,进行了土壤微生物对柴油的响应及对PAHs的修复研究。结果表明:(1)4个树种土壤微生物区系组成以细菌占优势,放线菌次之,真菌最少。(2)在各测定时间树种间土壤微生物总数对污染处理响应差异较大。栾树各污染处理组土壤微生物总数均高于对照组;樟树各污染处理土壤微生物在实验前期低于对照;广玉兰为污染处理组在4月份显著低于对照,而在其他月份多高于对照;马褂木在4月份均低于对照,其他月份为L1处理低于对照,L2、L3处理高于对照(1月L2除外)。(3)4个树种对照土壤中微生物总数随时间的变化都是从10月逐渐增加至翌年4月,然后不断减少至10月;污染处理土壤微生物总数呈现峰值提前或滞后现象,主要出现在1月或7月。真菌是控制PAHs降解的重要因素。(4)经过1a实验,各树种L1、L2处理土壤中的PAHs浓度已与对照土壤相当;L3处理各树种土壤中PAHs含量为马褂木>栾树>广玉兰>樟树。 Abstract:Polycyclic aromatic hydrocarbons (PAHs) are an important group of persistent organic pollutants that are widespread in environment. With rapid growth of population, sustained industrial development and urbanization, PAHs have become a growing concern and received much attention. The reason is that PAHs have toxicity to humans and their possible harmful effect on animals, plants and microbes in aquatic and terrestrial ecosystems. In order to reveal the responses of tree species to PAHs and to examine the remediation methods of diesel-oil contaminated soils using higher plants, a pot experiment was conducted to compare degradation of PAH concentrations in diesel-oil contaminated soils under four tree species, and to investigate how soil microbial flora make contributions on such degradation. One-year old seedlings of four tree species, Cinnamomum camphora, Magnolia grandiflora, Koelreuteria bipinnat, and Liriodendron chinense were selected and planted in PAH contaminated soils with different diesel-oil (0g/kg (control), 2g/kg (L1), 10g/kg (L2) and 50g/kg soil (L3)). The composition, abundance and dynamics of soil microbes in the four groups of soils were measured to provide theoretic evidences for assessing and selecting tree species for remediation of PAHs contamination. The results showed that (1) bacteria were the most dominant group in soil microbial flora in the four tree species, and accounted for 69.70%-93.87% of the total microorganism. The percentage of bacteria usually increased with increasing of diesel-oil concentration levels. Compared with in control treatments, the proportion of bacteria in soil microorganisms in PAH treatments were inhibited by diesel-oil concentrations, except in soil of Koelreuteria bipinnat. Actinomyces accounted for 2.71%-25.29% of total microbeorganisms, and the percentage decreased with the increases of diesel-oil concentrations in all treatments. For Koelreuteria bipinnat species, the percentages of Actinomyces in total soil microbial flora were smaller in contaminated treatments than in control. But the situation was opposite for Cinnamomum camphora species. The proportion of fungi in total soil microorganisms was 0.88%-5.83%, and the values were relatively promoted in low and medium diesel-oil concentration treated soils. (2) The microorganisms in the studied tree species soils exhibited different seasonal patterns to response to PAHs treatments. In Koelreuteria bipinnat soils, the number of total microbes was higher in contaminated treatments than in control; In Cinnamomum camphora soils, only at the early stage were the total microbes high in polluted treatments than in control. For Magnolia grandiflora species, the abundance of total microorganisms was higher in all diesel-oil treated soils than in control soils for the studied period, except in the month of April, when the number of microbes was higher in control than in other treatment soils. The total microbes were lower in polluted treatments than in control in Liriodendron chinense soils in April. But in other months, all treatment soils had higher microbes than in control except in L1 treatment. (3) In control soils, the quantity of total microbes gradually increased at the early stage of the study (from October, 2009), reaching the peaking value in April, 2010, and then decreased until in October, 2010. PAHs contaminations disturbed such dynamic patterns of microbial abundance. The maximum values of total microorganisms in were appeared in January or July in the treatments. It was found that fungi played an important role in controlling the degradation of PAHs in this study. One year later of the treatment, PAHs contents were similar in L1, L2 treatments' soils and in control soils for all four tree species plots. PAHs contents in L3 treatment's soils of each tree species were in the order of Liriodendron chinense > Koelreuteria bipinnat> Magnolia grandiflora>Cinnamomum camphora. 参考文献 相似文献 引证文献

Potential of grasses and rhizosphere bacteria for bioremediation of diesel-contaminated soils

The techniques available for the remediation of environmental accidents involving petroleum hydrocarbons are generally high-cost solutions. A cheaper, practical and ecologically relevant alternative is the association of plants with microorganisms that contribute to the degradation and removal of hydrocarbons from the soil. The growth of three tropical grass species (Brachiaria brizantha, Brachiaria decumbens and Paspalum notatum) and the survival of root-associated bacterial communities was evaluated at different diesel oil concentrations. Seeds of three grass species were germinated in greenhouse and at different doses of diesel (0, 2.5, 5 and 10 g kg-1 soil). Plants were grown for 10 weeks with periodic assessment of germination, growth (fresh and dry weight), height, and number of bacteria in the soil (pots with or without plants). Growth and biomass of B. decumbens and P. notatum declined significantly when planted in diesel-oil contaminated soils. The presence of diesel fuel did not affect the growth of B. brizantha, which was highly tolerant to this pollutant. Bacterial growth was significant (p < 0.05) and the increase was directly proportional to the diesel dose. Bacteria growth in diesel-contaminated soils was stimulated up to 5-fold by the presence of grasses, demonstrating the positive interactions between rhizosphere and hydrocarbon-degrading bacteria in the remediation of diesel-contaminated soils.

Impact of hydrocarbon type, concentration and weathering on its biodegradability in soil

The objective of this research was to investigate the impact of the hydrocarbon type and concentration, as well as the total effect of the natural weathering process to hydrocarbon biodegradability in sandy soil and the environment. In this experiment, sandy soil was separately contaminated with 0.5%, 1.0%, 2.0% and 3.5% of diesel and crude oils. Oil contaminated soil was taken from the Oil Refinery dumping sites after 9 years of weathering, and its concentration was adjusted to the above-mentioned levels. The biodegradation process was monitored by measuring CO2, evolution rate, hydrocarbon degradation rate and dehydrogenase activity. The favourable concentration ranges for the soil contaminated with diesel oil were 1.0%, with concentrations at about 2.0% causing slightly adverse effects to CO2 production which was overcome after 2 weeks, and with 3.5% diesel oil causing significant toxicity. For soil contaminated with crude oil, 2.0% was found to be optimum for effective biodegradation, with 3.5% crude oil also causing adverse effects to CO2 production, although less so than the same concentration of diesel oil. No adverse effect was obtained for any concentration of the weathered oil, as after the weathering process, the remaining contaminants in the soil were mostly poorly degradable constituents like asphaltenes, resins etc. It has been proposed that such residual material from oil degradation is analogous to, and can even be regarded as, humic material. Due to its inert characteristics, insolubility and similarity to humic materials it is unlikely to be environmentally hazardous.

Bioremediation of soil polluted with fuels by sequential multiple injection of native microorganisms: Field-scale processes in Poland

Research was conducted to estimate impact of the multiple bioaugmentation on the treatment of soil contaminated by fuels – diesel oil and aircraft fuel. The bacteria used to inoculate the remediation plots were isolated from the polluted soil and proliferated in field conditions. The amount of biomass applied to the polluted soil was set to ensure the total number of bacteria in soil 10 7–10 8 cfu/g d.w. The multiple inoculation of soil with indigenous bacteria active in diesel oil and engine oil (plot A) degradation increased bioremediation effectiveness by 50% in comparison to the non-inoculated control soil and by 30% in comparison to the soil that was inoculated only once. The multiple inoculation of soil with indigenous microorganisms was then applied in bioremediation of the soil polluted with double high concentration of diesel oil (soil B) and in bioremediation of the soil polluted with aircraft fuel (soil C). The process efficiency was 80% and 98% removal of TPH for soil B and C, respectively.

MAP kinase cell signaling pathway as biomarker of environmental pollution in the sponge Suberites domuncula

In the present study, we analyzed the effects of two major pollutants of the environment, tributyltin (TBT) and water-accommodated fraction (WAF) of diesel oil, on MAP kinase activation, apoptosis induction and DNA damage, in the marine sponge Suberites domuncula. Our results clearly demonstrated a differential activation of the MAPKs depending on the chemicals tested. TBT induced the activation of p38 and JNK while diesel oil enhanced activation of both ERK and p38. The activation of MAPKs was observed after 1 h exposure and 6 and 24 h of recovery in seawater. In addition, DNA fragmentation, assessed by two techniques, the Fast micromethod(®) and the TUNEL assay, was detected after sponges were treated with both chemicals. Moreover, the study of caspase 3/7 activity showed that apoptosis was induced and triggered with all concentrations of TBT but only at high diesel oil concentrations. After TBT exposure, a correlation was observed between JNK activation, caspase 3 activity and DNA damage while p38 activation followed the two latter parameters at high concentrations of diesel oil, suggesting that sponges enhanced a specific apoptotic pathway depending on the xenobiotic tested. This study demonstrated a high signal response by the sponge Suberites domuncula to the tested chemicals. Cell signaling pathway studies may thus be of use in water quality biomonitoring programs.

Scale up of diesel oil biodegradation in a baffled roller bioreactor

Diesel oil is a suitable substance to represent petroleum contamination from accidental spills in operating and transportation facilities. Using a microbial culture enriched from a petroleum contaminated soil, biodegradation of diesel oil was carried out in 2.2, 55, and 220 L roller baffled bioreactors. The effects of bioreactor rotation speed (from 5 to 45 rpm) and liquid loading (from 18% to 73% of total volume) on the biodegradation of diesel oil were studied. In the small scale bioreactor (2.2 L), the maximum rotation speed of 45 rpm resulted in the highest biodegradation rate with a first order biodegradation kinetic constant of 0.095 d −1. In the larger scale bioreactors, rotation speed did not affect the biodegradation rate. Liquid loadings higher than 64% resulted in reduced biodegradation rates in the small scale bioreactor; however, in the larger roller bioreactors liquid loading did not affect the biodegradation rate. Biodegradation of diesel oil at 5 rpm and 73% loading is recommended for operating large scale roller baffled bioreactors. Under these conditions, high diesel oil concentrations up to 50 g L −1 can be bioremediated at a rate of 1.61 g L −1 d −1.

Physical and Biological Treatment of Oil-Contaminated Soil in a Baffled Roller Bioreactor

ABSTRACT Physical and biological removal of diesel oil from contaminated soil was studied in a baffled roller bioreactor. Initially, the effects of four factors (soil loading, temperature, pH, and surfactant) on physical removal of diesel oil were investigated. Only the presence of a surfactant (sodium dodecyl sulfate [SDS]) demonstrated a significant effect on diesel oil removal. Diesel oil removal efficiency was increased from 32.0% to 63.9% in the presence of 100 mg/L SDS. Using a microbial culture enriched from contaminated soil, biological treatment of diesel oil polluted soil under different soil loadings (15% to 50%), different diesel oil concentrations (1 to 50 g/L), and different types of soil (sand, silt, and clay) was then investigated in the baffled roller bioreactor. Biodegradation consisted of both fast and slow stages for degradation of light and heavy compounds, respectively. All biodegradation experiments demonstrated significant decreases in diesel oil concentrations (88.3% in 14 days for initial diesel oil concentrations of 1000 mg/L and a wide range of soil loadings). The presence of silty or sandy soils enhanced the biodegradation rate compared to the control bioreactor (without soil). The sandy soil loading had no effect on the biodegradation results. Using the enriched culture, the baffled roller bioreactor was able to biodegrade high diesel concentrations (up to 50 g/L) with biodegradation rates of 112.2 and 39.3 mg/L· h during fast and slow stages, respectively.

Biodegradation of diesel oil in a baffled roller bioreactor

AbstractBACKGROUND: 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 (µmax and YXS) 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

Diesel Pollution Biodegradation: Synergetic Effect of Mycobacterium and Filamentous Fungi

To biodegrade the diesel pollution in aqueous solution inoculated with Mycobacterium and filamentous fungi. Bacteria sampled from petroleum hydrocarbons contaminated sites in Karamay Oilfield were isolated and identified as Mycobacterium hyalinum (MH) and cladosporium. Spectrophotometry and gas chromatography (GC) were used to analyze of the residual concentrations of diesel oil and its biodegradation products. From the GC data, the values of apparent biodegradation ratio of the bacterial strain MH to diesel oil were close to those obtained in the control experiments. Moreover, the number of MH did not increase with degradation time. However, by using n-octadecane instead of diesel oil, the real biotic degradation ratio increased to 20.9% over 5 days of degradation. Cladosporium strongly biodegraded diesel oil with a real degradation ratio of up to 34% after 5 days treatment. When the two strains were used simultaneously, a significant synergistic effect between them resulted in almost complete degradation of diesel oil, achieving a total diesel removal of 99% over 5 days of treatment, in which one part of about 80% and another part of about 19% were attributed to biotic and abiotic processes, respectively. The observed synergistic effect was closely related to the aromatics-degrading ability of Cladosporium, which favored the growth of MH and promoted the bioavailability of diesel oil.

Effect of Ultrasound on Surfactant-Aided Soil Washing

The use of ultrasound as an enhancement mechanism in the surfactant-aided soil-washing process was examined by conducting desoption tests of soils contaminated with naphthalene or diesel-oil. The experiments were conducted to elucidate the effect of ultrasound on the mass transfer from soil to the aqueous phase using naphthalene-contaminated soil. In addition, the use of ultrasound for the diesel-oil-contaminated soil was investigated under a range of conditions of surfactant concentration, sonication power, duration, soil/liquid ratio, particle size and initial diesel-oil concentration. The ultrasound used in the soil-washing process significantly enhanced the mass transfer rate from the solid phase to the aqueous phase. The removal efficiency of diesel-oil from the soil phase generally increased with longer sonication time, higher power intensity, and large particle size.

Degradation of diesel oil in soil using a food waste composting process

We investigated the simultaneous degradation of diesel oil in soil and the organic matter in food waste by composting in 8 l reactors. Using a 0.5 l/min air flow rate, and 0.5-1% diesel oil concentrations together with 20% food waste, high composting temperatures (above 60 degrees C) were attained due to the efficient degradation of the food waste. Petroleum hydrocarbons were degraded by 80% after only 15 days composting in the presence of food waste. In a 28 l reactor scale-up experiment using 1% oil, 20% food waste and 79% soil, removal efficiencies of petroleum hydrocarbons and food waste after 15 days were 79% and 77%, respectively.

Moulting frequency and behavioural responses to salinity and diesel oil in Austromegabalanus psittacus (Molina) (Cirripedia: Balanidae)

Moulting frequency and behavioural responses to salinity and diesel oil concentration were studied in specimens of the giant barnacle Austromegabalanus psittacus (Molina). Moulting frequency and frequency and type of cirral beat, in addition to opercular valve closure time, were measured under controlled conditions. A binary factorial experimental design was carried out at salinities of 20 and 30‰ and diesel oil concentrations of 0.1 and 0.5% v/v. Moulting frequency was greater at 30‰ than at 20‰ salinity and at 0.1% oil concentration than at both 0.5% oil concentration and in controls; it is unlikely that this signified variations in growth. Diesel oil provoked lethal effects at 0.5%, with an average lethal time of 8 days; at 0.1%, only sublethal effects were generated. Cirral beat frequency was greater at 0.1 and 0.5% diesel oil concentration than in controls. This was probably associated with an increase in metabolism, since the most frequent cirral beats are associated with respiration and the active capture of plankton. The effects of the contaminant varied with time, as observed at 15 and 60 min. The opercular valve closure time was longer in controls and decreased as diesel oil concentration increased. Results suggest that this species is highly resistant to pollution, although contaminants could provoke changes in the feeding and growth of specimens. Local variations in salinity have only minor effects on barnacle behaviour.

Effect of soil contamination with diesel oil on yellow lupine yield and macroelements content

The study has been undertaken to assay the effect of soil contamination with diesel oil on yellow lupine yield and macroelement contents as well as to examine the relationships between the accumulation of macroelements versus the yellow lupine yielding and some yield quality characteristics. The influence of soil pollution with refinery products depended on the type of soil, diesel oil concentration in soil and mineral fertilisation. Increasing contents of soil pollution with diesel oil promoted higher concentrations of phosphorus, sodium, magnesium and calcium in aboveground parts and roots of yellow lupine. More severe contamination was also responsible for depressed yield of yellow lupine aboveground parts and roots as well as accumulation of nitrogen in aboveground parts and potassium in roots of the crop. The addition of nitrogen to soil diversified the yielding and content of macroelements in yellow lupine. The direction these changes took depended on the plant organ, type of soil and degree of diesel oil contamination.

Hydrocarbon removal in an experimental gravel bed constructed wetland

Two outdoor subsurface flow beds (control and experimental, 10 m x 1 m) were filled with a substrate of pea gravel (3-6 mm) to a depth of 60 cm. The experimental bed or small-scale constructed wetland was originally planted with Typha seedlings at a density of 7.5 plants/m2. Both beds (experimental and control) were treated with the same aqueous concentrations of diesel oil under identical dosing conditions. The average overall hydrocarbon removal efficiencies at the three monitored depths (top, middle and bottom) in the subsurface systems were 80.1 +/- 9.8%, 78.0 +/- 9.1% and 71.6 +/- 10.0% in the experimental bed and 72.3 +/- 11.9%, 69.1 +/- 10.3% and 63.4 +/- 9.4% in the control bed. The differences in the hydrocarbon removal efficiencies between corresponding months in 1999 and 2000 were statistically analysed and are generally not significant. The individual hydrocarbon removal efficiencies exceeded 60% in the top sections of both beds except for C-11 and C-25 with C-23 and C-26 also reduced in the control bed. Overall differences in the removal efficiencies of the planted and the unplanted beds as well as at different depths in both systems, indicate that Typha related removal processes complementing adsorption onto the gravel substrate are occurring.

Quantitative determination of diesel oil in contaminated edible oils using high‐performance liquid chromatography

AbstractA simple and reliable high‐performance liquid chromatography method for the analysis of diesel oil in contaminated edible oils is described. Analysis performed using a diol column with a mobile phase of heptane and isopropanol (94∶6, vol/vol). Although baseline separation between diesel and other background fluorescent components was not achieved, quantitation was still possible using baseline integration. The method is linear over the range of 5–1000 μg/g with a correlation coefficient (r2) of 0.9984. Average recoveries from spiked edible oils were 94.4–101.3%, with a limit of quantitation (LOQ) of 5 μg/g for sunflower oil, palm olein, and groundnut oil. Corn oil has a higher content of ester components, thus, LOQ was slightly worse (40 μg/g). The applicability of the method was confirmed by gas chromatography‐mass spectroscopic detection to show the presence of diesel hydrocarbons in the suspected contaminated crude palm oil. This procedure provides a simple and sensitive method for determining diesel oil concentration in contaminated edible oils without prior sample cleanup or extraction.

Oil Biodegradation Potential in Alpine Habitats

We enriched cold-adapted diesel-oil-degrading microorganisms (inocula) from 29 alpine habitats (soils and glaciers) and evaluated the biodegradation of diesel oil at low temperatures. All microbial inocula tested utilized diesel oil (5000 mg L–1) as the sole carbon source at 4 and 10°C. Not only oil-contaminated samples, but also samples from uncontaminated sites contained efficient biodegraders. Ten inocula were selected to study the effect of diesel oil concentration and incubation time on biodegradation at 10°C. The time course of biodegradation was similar at all three concentrations (500, 1200, 5000 mg L–1) tested. Biodegradation occurred mainly during the first 6 d of incubation. Complete biodegradation of the diesel oil added was not achieved with any of the inocula tested; at least ca. 25% of the initial diesel-oil-concentration remained.

Oil Biodegradation Potential in Alpine Habitats

We enriched cold-adapted diesel-oil-degrading microorganisms (inocula) from 29 alpine habitats (soils and glaciers) and evaluated the biodegradation of diesel oil at low temperatures. All microbial inocula tested utilized diesel oil (5000 mg L-') as the sole carbon source at 4 and 10oC. Not only oil-contaminated samples, but also samples from uncontaminated sites contained efficient biodegraders. Ten inocula were selected to study the effect of diesel oil concentration and incubation time on biodegradation at 100C. The time course of biodegradation was similar at all three concentrations (500, 1200, 5000 mg L-') tested. Biodegradation occurred mainly during the first 6 d of incubation. Complete biodegradation of the diesel oil added was not achieved with any of the inocula tested; at least ca. 25% of the initial diesel-oil-concentration remained.