Browsing by Author "Duran, Robert"
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Item Open Access Are alkane hydroxylase genes (alkB) relevant to assess petroleum bioremediation processes in chronically polluted coastal sediments?(Springer Science Business Media, 2011-11-30T00:00:00Z) Païssé, Sandrine; Duran, Robert; Coulon, Frederic; Goni-Urriza, MarisolThe diversity of alkB-related alkane hydroxylase sequences and the relationship between alkB gene expres- sion and the hydrocarbon contamination level have been investigated in the chronically polluted Etang-de-Berre sediments. For this purpose, these sediments were main- tained in microcosms and submitted to a controlled oil input miming an oil spill. New degenerated PCR primers targeting alkB-related alkane hydroxylase sequences were designed to explore the diversity and the expression of these genes using terminal restriction fragment length polymorphism fingerprinting and gene library analyses. Induction of alkB genes was detected immediately after oil addition and their expression detected only during 2 days, although the n-alkane degradation was observed throughout the 14 days of incubation. The alkB gene expression within triplicate microcosms was heterogeneous probably due to the low level of alkB transcripts. Moreover, the alkB gene expression of dominant OTUs has been observed in unoiled microcosms indicating that the expression of this gene cannot be directly related to the oil contamination. Although the dominant alkB genes and transcripts detected were closely related to the alkB of Marinobacter aquaeolei isolated from an oil- producing well, and to alkB genes related to the obligate alkanotroph Alcanivorax borkumen- sis, no clear relationship between the oil contamination and the expression of the alkB genes could be established. This finding suggests that in such coastal environments, alkB gene expression is not a function relevant enough to monitor bacterial response to oil contamination.Item Open Access Enhanced pilot bioremediation of oily sludge from petroleum refinery disposal under hot-summer Mediterranean climate(Elsevier, 2021-10-23) Said, Olfa Ben; Cravo-Laureau, Cristiana; Armougom, Fabrice; Cipullo, Sabrina; Khelil, Meriem Ben; Yahiya, Marouen Ben Haj; Douihech, Abdeljabar; Beyrem, Hamouda; Coulon, Frederic; Duran, RobertLarge pilot scale bioremediation approaches were implemented for the treatments of oily sludge (OS) characterised by alkaline pH (pH > 9), high concentration of metals (3% dry weight) and high total petroleum hydrocarbons content (TPH) rangingbetween 22,000 and 67,300 mg kg −1 from a Tunisian petroleum refinery. The treatments included bioaugmentation and biostimulation approaches with autochthonous isolated bacterial strains and consortia. Chemical, microbial, and ecotoxicological analyses were performed over a period of 180 days incubation. The bioremediation treatments favoured the development of Proteobacteria, Firmicutes and Bacteroidetes following an ecological succession of specialist bacterial groups, first associated to hydrocarbon degradation (e.g. Marinobacter and Alcanivorax) that resulted in a greater extent of TPH-degradation (up to 80%), and the selection of metal resistant bacteria including Hyphomonas, Phaeobacter, and Desulfuromusa. The best performances were obtained when bioaugmentation and biostimulation were combined. Over 90% of the TPH initial concentration was degraded over 180 days, which was accompanied with a 3-fold reduction of ecotoxicity. Our study demonstrates the efficacy of large pilot scale bioremediation of highly contaminated oily sludge, providing the evidence that the management of autochthonous microbial communities is of paramount importance for the success of the bioremediation process.