Production of Biosurfactants by Hydrocarbons Degrading Bacteria Isolated from Soummam Watershed Sediments of Bejaia in Algeria

摘要

Hydrocarbons degrading bacteria were isolated from sediments of the Soummam watershed of Bejaia (Algeria). Eleven bacteria strains were isolated using an enrichment technique, method in mineral salt medium, with various hydrocarbons as the sole carbon source. The biodegradation confirmation of various hydrocarbons by these isolates was tested by hole-plate diffusion technique. Out of eleven cultures, nine had shown the growth around the holes. The isolates were screened for biosurfactant producing using oil spreading test and emulsification activity. The value of emul-sification activity varied from 55.7 ± 1.1 to 78.5 ± 0.5%. The diameter of clear zone obtained varied between 20.7 ± 1.2 mm and 33-7 ± 1.2 mm, it was hence important compared to the negative control. Five bacterial strains were identified as Alcaligenes faecalis, Ochrobactrum, Cellulosimi-crobium, Pseudomonas stutzeri, and Rhodococcus ruber by using physiochemical characterization and MALDI-TOF mass spectrometry tools. The best production of crude biosurfactant by the identified bacterial strains was found in R. ruber which produced 6.7 ±0.1 g/L of the crude biosurfactant after 168 h incubation in mineral salt medium (MSM) supplemented with 2% of glucose and 0.1 g/L of yeast extract. The biosurfactant produced by all bacterial strains showed a high emulsification index (E_24). where P. stutzeri revealed the highest one (92.2 ± 1.1%).