Isolation of alkane-degrading bacteria from deep-sea Mediterranean sediments.

AIMS: To isolate and identify alkane-degrading bacteria from deep-sea superficial sediments sampled at a north-western Mediterranean station. METHODS AND RESULTS: Sediments from the water/sediment interface at a 2400 m depth were sampled with a multicorer at the ANTARES site off the French Mediterranean coast and were promptly enriched with Maya crude oil as the sole source of carbon and energy. Alkane-degrading bacteria belonging to the genera Alcanivorax, Pseudomonas, Marinobacter, Rhodococcus and Clavibacter-like were isolated, indicating that the same groups were potentially involved in hydrocarbon biodegradation in deep sea as in coastal waters. CONCLUSIONS: These results confirm that members of Alcanivorax are important obligate alkane degraders in deep-sea environments and coexist with other degrading bacteria inhabiting the deep-subsurface sediment of the Mediterranean. SIGNIFICANCE AND IMPACT OF THE STUDY: The results suggest that the isolates obtained have potential applications in bioremediation strategies in deep-sea environments and highlight the need to identify specific piezophilic hydrocarbon-degrading bacteria (HCB) from these environments.

Management of osteoradionecrosis of the jaws: an analysis of evidence.

AIM: To review and discuss the management of jaw bone osteoradionecrosis (JORN) based on levels of evidence. METHODS: The Medline/PUBMED and Cochrane search was performed to identify all studies on the management of JORN, published in English, French, and German during January 1975-October 2007. Only clinical researches were identified and classified into four levels of evidence before being examined. All references of the retrieved articles were analysed. FINDINGS: Seventy three articles and their additional 45 citations were evaluated. Most of the eligible literature provided observational evidence. Hyperbaric oxygen therapy (HBOT) is an adjunct; however, its clinical usefulness remains controversial. A conservative approach should be limited to early-onset JORN, while radical surgery is indicated for an advanced or refractory lesion. Free tissue transfer is the reconstruction of choice for large defects without the need of HBOT. Some new technologies have also been studied, including ultrasound, biological molecules, distraction osteogenesis and antioxidant agents. CONCLUSIONS: Most of the reports on the treatment of JORN offer weak evidence. Current information seems insufficient for establishing the definite treatment guideline; thus, well-designed studies with long-term clinical data are encouraged.

Effects of crude oil on phospholipid fatty acid compositions of marine hydrocarbon degraders: estimation of the bacterial membrane fluidity.

In this study, we investigated, in vitro, the effects of petroleum hydrocarbons on the phospholipid ester-linked fatty acid composition of Corynebacterium sp. Strain 8. The usual ratio of monounsaturated fatty acids E/Z (or trans/cis) was calculated. This ratio led to unexpected results because we found similar values for growths on either a hydrophobic substrate (crude oil) or a soluble carbon source (rich medium). The use of such an indicator seemed limited for monitoring an environmental stress, so we proposed an index based on the homeoviscous adaptation theory. A membrane viscosity index was defined and applied to Corynebacterium sp. Strain 8 (in vitro growth) and to a sedimentary community (in situ experiment). The results allowed us to estimate the membrane fluidity of both an isolated strain and a bacterial community in accordance with the medium hydrophobicity.

Burial, exportation and degradation of acyclic petroleum hydrocarbons following a simulated oil spill in bioturbated Mediterranean coastal sediments.

A field study was conducted in a French Mediterranean littoral (Gulf of Fos) in order to determine the role of bioturbation processes during the bioremediation of oil-contaminated sediments. Inert particulate tracers (luminophores) and Arabian light crude oil were deposited at the surface of sediment cores incubated in situ for 2, 6 and 12 months. After incubation, luminophores and hydrocarbons presented roughly similar depth distributions in the sediment, showing a continuous burial of material until 55 mm depth. Short-chain (< or = n-C25) n-alkanes were totally removed from the sedimentary column after 6 months, whereas approximately 20% of heavier n-alkanes (e.g. n-C30) and of isoprenoid hydrocarbons (pristane (Pr) and phytane (Ph)) remained at the end of the experiment. The determination of the degradation constant and the turn-over rate of individual hydrocarbon indicated that C17-25 n-alkanes were degraded two to three times faster than longer homologues and than pristane and phytane. Using the 17alpha,21beta-C30-hopane as an internal inert reference, we could demonstrate that, after 12 months of in situ incubation, 55% of the losses of the n-alkanes < or = C25 and 35% of the losses of the heavier n-alkanes and of Pr and Ph were due to biodegradation processes. These results demonstrate that the activity of benthic organisms can have a significant influence on the qualitative and quantitative fate of acyclic hydrocarbons following a petroleum contamination in marine coastal sediments.

Influence of n-alkanes and petroleum on fatty acid composition of a hydrocarbonoclastic bacterium: Marinobacter hydrocarbonoclasticus strain 617.

This study concerns the effects of various long-chain n-alkanes, n-alkane mixtures and Arabian Light crude oil on the fatty acid (FA) composition of a sedimentary marine bacteria (Marinobacter hydrocarbonoclasticus strain 617), growing under aerobic conditions. The cultures with n-alkanes, as compared with soluble carbon sources, led to greater amounts of saturated and methyl branched FA (mainly belonging to a delta10 series). We observed the appearance or increase of saturated and unsaturated FA with the same carbon chain length (CCL) as the n-alkane carbon source (maximum for n-alkane CCL corresponding to the 'range' of the de novo synthesized fatty acids). We also observed a strong control of the oddness/evenness of the CCL of the FA by the oddness/evenness of the n-alkane. A n-alkane utilization index, (saturated + branched)/monounsaturated fatty acids (SAFA + BFA/MUFA) enabled discriminating between soluble carbon sources and hydrocarbons.

Controlled marine ecosystems in the investigation of oil biodegradation at sea.

In the marine environment, petroleum is subject to the action of physico-chemical weathering and microbial biodegradation. Experimental controlled ecosystems have provided essential information about the fate of petroleum at sea.

Adjvant treatment of tongue and floor of the mouth cancers.

Since January 1974, 95 patients with anterior tongue and floor of the mouth cancers were included in a randomized trial. After stratification according to staging and initial treatment, one-third of the patients received chemotherapy for 2 years (methotrexate 400 mg followed by citrovorum factor 100 mg + bleomycin 60 mg/week, during the first 15 weeks), one-third of the patients received immunotherapy with weekly C. parvum injections during 2 years, while the remaining third did not receive any treatment. If adjuvant treatment seems to delay recurrence it did not significantly decrease the recurrence rate. Survival is also not signigicantly modified by adjuvant treatment and was better for patients with small tumors. Patients who previously received radiotherapy did not benefit from adjuvant therapy.