Biodégradation des hydrocarbures pétroliers par des bactéries marines: Application en traitement des eaux de mer contaminées par le pétrole

Abstract : The aim of this work is to study the hydrocarbon degradation capacities of marine bacteria as well as the production of biosurfactants for bioremediation purpose of crude oil contaminated seawater. Fifteen (15) bacterial strains able to utilize crude oil as sole carbon and energy source and produce biosurfactants were successfully isolated. Based on these results, an isolate designed as strain SdK644 was selected. It was very closely related to Marinobacter hydrocarbonoclasticus with 16S rRNA gene sequence similarity of 97.44 %. Strain Sdk644 could grow on crude oil up to 5% (v/v) in neutral-alkaline conditions and with optimal NaCl concentration of 23 g/L. This strain degraded 83.68% of n-alkanes in crude oil (1%, v/v) over a period of 21 days. SdK644 strain also mineralized hexadecane (41%) and tetracosane (11%) at initial concentration of 1 g/L, as well as 100 mg/L of pyrene (38%) and anthracene (31%) after 20 days of incubation. High production efficiency of biosurfactant from SdK644 was achieved after 3 days of incubation, using waste frying oil (2%, w/v), NH4Cl as nitrogen source, C/N ratio of 50, pH 7.0 and NaCl concentration 23 g/L. The yield of biosurfactant “HF644” obtained was 4.93 g/L. HF644 agent decrease surface tension at 31 mN/m, with critical micelle concentration of 787 mg/L. The biosurfactant activity was stable over a wide range of temperature (-18‒121 °C), pH (2‒10) and salinity (0‒200 g/L). Toxicity bioessai of HF644 biosurfactant showed no significant lethality against Artemia nauplii. Moreover, the results demonstrated that HF644 biosurfactant was 2 times greater than that of a synthetic surfactant Tween 80 in crude oil solubilization. Finally, bioremediation experiments showed that combination of HF644 biosurfactant with SdK644 inoculum leads to maximal crude oil removal in comparison with inorganic nutrient stimulants and seawater indigenous microflora.
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Billal Zenati. Biodégradation des hydrocarbures pétroliers par des bactéries marines: Application en traitement des eaux de mer contaminées par le pétrole. Autre. Université Saad Dahlab Blida 1 (Algérie), 2018. Français. ⟨tel-02173171⟩

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