Microbial biodegradation potential of petroleum-and nature oils by indigenous hydrocarbon degrading bacteria isolated from petro-contaminated sites

الملخص EN

The study was carried out as an effort at developing active natural petroleum hydrocarbon degraders that could be of relevance of bioremoval of petro-and non-petro oil pollutants from contaminated sites, a collection of ١٠ bacterial isolates as well as ٣ yeast strains and Enterobacter clocace spp.

disssolvens strain as efficient petro-hydrocarbon degraders were employed in this study to reach to this target.

These bacterial isolates were identified to genus and species level using matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALD-TOF-MS) with high degree of precision (٢.١١١-٣.٣٦١) as an efficient approach for unambiguous identification process in real sample within minutes.

Two experimental techniques, namely respirometric method (CO٢ production) and the redox indicator ٢,٦-dichlorophenol indophenol (DCPIP) test were carried out to evaluate the capacity of the tested organisms to utilize monoaromatic hydrocacbons (BTEXmixture) and/or n-hexadecane as an excellent substrates in the study of hydrocarbon biodegradation in the tested media, individual and/or mixed bacterial and yeast consortium.

The results indicated that the tested organisms showed different rate and extent of growth as well as mixed bacterial–or yeast consortium showed more growth and degradation.

Also, some growth condition factors that affect the success of biodegradation were determined, and obtained results revealed that pH (٧.٠), temperature (٣٠-٣٥°C), salinity (٠.٠% and ٠.٥% NaCl) and incubation period (١١ days) were suitable for the most tested bacteria.

The results showed also that only five bacterial strains out of ١٠ strains namely: Sphingobacterium thalpophilum QBII-٦, Pseudomonas nitroreducens RdI-١٤, Bacillus subtilis ssp subtilis GH-٥, B.

atrophaeus GH-٦ and B.

licheniformis RdI-١٧ as well as Ent.

clocace spp.

disssolvens exhibited the highest capability to metabolize a diverse range petroleum oils (crude oil, diesel oil, engine oil, used engine oil) and natural oils (corn oil, used corn oil, sunflower oil and used sunflower oil), and these five bacterial types could be applicable in bioremediation process of pollutants after carrying out future studies in field condition as a final goal.