Biodegradation Of Diesel And Isomerate By Pseudomonas Aeruginosa And Brevibacillus Laterosporus Isolated From Hydrocarbons Contaminated Soil.

Résumé: Biodegradation of petroleum hydrocarbons is more effective, powerful and economical provident than physical and chemical techniques. The most important process uses newly isolated indigenous microorganisms from contaminated sites. Our study aims to isolate, characterize the diversity of microbial communities specifically involved in the biodegradation of diesel within polluted soil. Two bacterial strains were isolated from hydrocarbons-contaminated soils collected from the refinery of Arzew, Northern Algeria, using the enrichment technique. The morphological characteristics of the colonies, the cell structure, Gram staining and the observation of the bacterial spore were studied, the biochemical characterization were performed by the use of biochemical galleries. The bacterial strains were identified as Pseudomonas aeruginosa (P1) and Brevibacillus laterosporus (B2). The ability of P. aeruginosa (P1) and B. laterosporus (B2) to degrade diesel was performed by measuring the optical density, colony forming unit counts (CFU/ml), gravimetric method. The degradation of Isomerate by the two isolates was analyzed by gas chromatography with flame ionization detector (FID). Results indicated that the isolates can use diesel as sole source of carbon. Biodegradation of diesel by P1 and B2was indicated by an increase in the optical density of culture and colony forming unitcounts (CFU/ml)from 7×104 and 2.3×103 CFU/ml to 5.9×109 CFU/ml and 3.4×108 CFU/ml on day 8 respectively. The biodegradation potential of diesel was 20% (for P1) and51.35% (for B2) during 12 days f ncubation.Isolate P1have the highest capability of diesel degradation, thiswas consistent with the complete degradation in five days of four components of Isomerate(C3, I-C4, 2-3dimethylbutane and toluene) and more than 90% of 8 other components (I-C5, cyclopentane, 2methylpentane, 3methylpentane, hexane, benzene, Et. Benzene and O. Xylene). Isolate B2 completely degraded hexane and more than 80% of C3, I-C4, 2 methylpentane and toluene.

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