Gilbert Mille

Biodegradation of hydrocarbons by an extremely halophilic archaebacterium

An archaebacterium (strain EH4) able to biodegrade saturated and aromatic hydrocarbons has been isolated from a sail‐marsh. Maximum growth on eicosane (62% of biodegradation, 10 h generation time) was reached in a medium prepared with a natural hypersaline water collected from a salt‐marsh (3.5 mol/1 NaCl concentration). No growth on hydrocarbons was observed for NaCl concentration lower than 1.8 mol/1.

Hydrocarbon balance of a site which had been highly and chronically contaminated by petroleum wastes of a refinery (from 1956 to 1992)

Petroleum hydrocarbon pollution in the Gulf of Fos (South France) was studied following the cessation of petroleum waste discharge from an oil refinery in the Lavera area. Sediments were collected in core samples of 30 cm at eight stations along a radial from the refinery to the open sea. Petroleum contamination has been detected up to the beginning of the open sea but decreased gradually (from 40 to 3 g kg−1 sediment dry wt). GC profiles (aliphatics and aromatics) are characteristic of petroleum. They reveal the disappearance of short chain n-alkanes (up to C25) and of one and two aromatic ring compounds, the increase and the modification of the UCM depends on the depth and the situation, resulting from weathering processes. Biomarkers and three to five aromatic ring compounds are unaltered whatever the depth and the location. If some petroleum hydrocarbons are present for the open sea stations (perhaps from other sources), natural and pyrolytic hydrocarbons are also detected. Sediments from the open sea could be considered to be unpolluted (less than 0.1 g kg−1), and unaffected by the refinery wastes two years after the end of overspills.

Changes in the chemical structure of low rank coal after low temperature oxidation or demineralization by acid treatment: Analysis by FT-i.r. and u.v. fluorescence☆

The studies have been conducted on low rank coal: Flambant de Provence, France, PRV=0.44 FTIR and UV synchronous fluorescence spectroscopy are used to study structural changes in low rank coal after natural oxidation or acid (HCl/HF) demineralization. The observed variations deal mainly with a decrease in aliphatic structures and an increase in the oxygenated species. A quantitative oxidation study of the effect of temperature, time, mineral matter and oxygen concentrations has been conducted by FTIR. An attempt to describe the oxygenated species by FTIR and to compare their evolution has been conducted. Various oxidation mechanisms are proposed according to the results.

Long term evolution of petroleum biomarkers in mangrove soil (Guadeloupe)

Abstract In March 1986, plots of a peaty mangrove were delimited and polluted by Arabian Light crude oil. Superficial sediments were sampled (0–5; 5–10 and 10–20 cm core section) in 1987, 1990, 1994 and petroleum hydrocarbons were analysed by FID-GC, high resolution GC-MS and MRM GC-MS. One year later, no significant evolution of the petroleum chemical composition was noted. Four years later, n -alkanes had strongly decreased and isoprenoids were predominant. Eight years later, isoprenoids were severely degraded and biomarkers were more or less altered as follows in the declining order of importance: steranes > hopanes > bicyclic terpanes > triand tetracyclic terpanes > diasteranes > norhopanes and triaromatic steroids > C-ring monoaromatic steroids. For steranes, the following order of degradation can be proposed C 26 > C 27 > C 28 > C 29 > C 30 with the stereochemical degradation sequence aaa 20R > αββ 20(R + S) > ααα 20S. Regarding pentacyclic terpanes, a decreasing removal is observed in the order C 35 > C 34 > C 33 > C 32 > C 31 with a preferential degradation of the 22R epimers compared to the 22S epimers. The C 30 -17α(H), 21β(H)-hopane appears more sensitive to weathering than its higher homologues. We also observed that there was selective degradation with drimanes/homodrimanes, diasteranes/steranes and norhopanes/hopanes. A light depletion of the C 20 –C 21 triaromatic steroids can be noted whereas no degradation of C-ring monoaromatic steroids is observed. Biomarkers, widely used in geochemistry, can be also used to follow the weathering of petroleum in natural conditions and can be considered as environmental markers.

Subfractionation, characterization and photooxidation of crude oil resins

Resins of five crude oils were obtained using SARA fractionation. The maltenic fraction of Blend Arabian Light, was further separated into six polar fractions. These fractions which are the constituents of the resins were analysed by FTIR spectroscopy. They appeared to be more oxidized, more aliphatic and less aromatic than asphaltenes. Photooxidation of resins showed that they are easily oxidizable and much more influenced by photooxidation than asphaltenes. The principal effect of photooxidation are: (i) increase of carbonyl group amounts and particularly formation of carboxylic groups, (ii) oxidation of sulfoxide in sulfone group, (iii) oxidation of alkyl chains and of aromatic rings (quinone structures).

The origins of hydrocarbons trapped in the lake of berre sediments

Abstract For decades, the Lake of Berre (France) - a heavily contaminated ecosystem - has received hudge amounts of hydrocarbons from refineries, petrochemical plants, transportation systems, in addition to those originating from marine and terrestrial biogenic inputs. The purpose of this work was to identify the sources of hydrocarbons trapped in the sediment, using characterization indices, based on n-alkane and isoprenoid abundance ratios obtained from GC/MS analysis. The upper sediment was sampled from 5 widely-separated stations. In each station, the subsurface (0–10 cm) and the underlaying (10–20 cm) sediment were separately analyzed by gravimetry, GC/FID and GC/MS. Total hydrocarbon contents ranged from 63 to more than 6100 mg.kg −1 1 of dry sediment. Qualitative analysis of the saturated hydrocarbon fraction demonstrated the presence of weathered petroleum residues of mixed geochemical origins, as evidenced by the presence of different cyclic alkanes known as biomarkers. Total polyaromatic hydrocarbon contents ranged from 29 to more than 2300 mg.kg −1 1 of dry sediment, associated with molecular indexes suggesting the occurence of combustion processes prior to sedimentation. Petrogenic, pyrolitic, and biogenic sources were discriminated, with reference to previous surveys of the same area or of adjacent areas. With regard to biogenic hydrocarbons, terrestrial sources seem generally predominate, except in the Northwestern area where n-alkane and isoprenoid abundance ratios are more characteristical of organic matter from a marine origin.

In vitro photooxidation of crude oil maltenic fractions : Evolution of fossil biomarkers and polycyclic aromatic hydrocarbons

Abstract Photooxidation is an important transformation pathway for petroleum spilled in the marine environment. The maltenic fraction of ten crude oils was exposed to sunlight. Acidic and non-acidic photoproducts were analysed by FTIR spectroscopy and by GC/MS. A formation of carboxylic acids, straight-chain ketones and alcohols was observed. The GC/MS analyses of residual alkanes showed a preferential alteration of branched alkanes. The analyses of biomarkers such as drimanes, hopanes and steranes indicated that the GC/MS indices widely used in geochemistry, presented a great stability after photooxidation except for the Tm (Tm+Ts) ratio. Concerning the polycyclic aromatic hydrocarbons (PAHs), naphthalene and its derivatives were severely altered by photooxidation whereas, phenanthrene, dibenzothiophene and their derivatives were more recalcitrant. Methyl derivatives were more degraded than their parent molecules and in the case of methyl phenanthrenes, the 2-methyl phenanthrene had a great stability. The following sequence of increasing photodegradability of mono methylated phenanthrenes (MP) can be proposed: 2-MP

Hydrocarbon biodegradation and hydrocarbonoclastic bacterial communities composition grown in seawater as a function of sodium chloride concentration

Bacterial strains have been enriched and isolated from marine sediment of an oil-contaminated area and grown in a culture medium prepared with synthetic seawater (0.4 M NaCl) and containing crude oil (EH1 community) or an hydrocarbon mixture (EH2 community) as sole energy and carbon source. The strains isolated from crude oil were code named EH1 community; those from the mixture EH2 community. Hydrocarbon biodegradation in enrichment culture was maximum for 0.4 M NaCl and decreased for NaCl concentrations above or below this value. However, the effect of NaCl concentration depended somewhat on the nature of the substrate supplied for growth. With 2 M NaCl, the saturated fraction of crude oil was the only one significantly biodegraded (27%). In contrast, the level of biodegradation remains rather high for the standard hydrocarbon mixture: 80–95% for saturated hydrocarbons, 17–34% for aromatics. Few phenotypic differences were noted between strains growing on crude oil (EH1) and/or mixture of hydro-carbons (EH2). The clustering of the strains isolated after enrichment at various NaCl concentrations (from 0 to 2 M NaCl) demonstrated the presence of ecotypes of similar bacterial species. From initial enrichments most of the strains were Gram-negative, aerobic rods, possessing few exoenzymes and using mostly fatty acids and organic acids as carbon and energy sources.

The potential application of biosurfactants in combatting hydrocarbon pollution in marine environments.

During growth on specific substrates, a large variety of microorganisms synthesize compounds with tensio-active properties called biosurfactants (Cooper, t986; Haferburg et el., 1986; Reiser et aL, 1989; Rosenberg, 1986). Such molecules are extraeellular or localized on the cell surface. The chemical composition of biosurfaetants is very variable: fatty acids, phospholipids, glycolipids, !ipopeptides, l ipopro te ius , po lysaceha r ide l ip id complex , polysaecbaride-protein complex. It depends on strains, substrates and growth conditions. Biusurfaetams are amphipathie molecules, a property that enables them to concentrate at the interface and reduce surface and interface tensions. They are often very good emulsifiers, frequently producing emulsions much more stable than those obtained with chemical surfactants. The existence of this property in a microorganism is essential when considering the application of a biological treatment to pollution by hydrocarbons. It is worth noting that the diversity of the techniques used to measure the emulsifying activity on crude or purified material makes it difficult to compare the hydrocarbon emulsifying capacity of a given biosurfactant (table 1).

Anaerobic oxidation of 1-n-heptadecene by a marine denitrifying bacterium

SummaryA denitrifying bacterium showing typical characteristics of Pseudomonas sp. (Al1) capable of growth on 1-heptadecene as the sole source of carbon and energy has been isolated from a hydrocarbon-polluted marine sediment by using classical enrichment techniques. The generation time for anaerobic growth on 1-heptadecene was 24 h, and the percentage of hydrocarbon degradation under anaerobic conditions ranged from 19 to 23%. The emulsifying capacity was observed and suggested that Al1 cultivated anaerobically on heptadecene produced surface-active agents.