Biodegradation of Normal-Hexadecane in Soil by Pseudomonas and Selected Native Bacteria from Crud Oil Contaminated Regions

The biodegradation of normal-hexadecane by bacteria is one of the important aspects of bioremediation. The aim of this study was to investigate degradation of normal hexadacane (with level of contamination، 2500 mg. kg-1) by Pseudomonas aeruginosa، Pseudomonas putida and native bacteria of contaminated regions in the presence of NPK (three types of fertilizer: urea with 46% nitrogen، ammonium phosphate with 21% nitrogen and 46% phosphor and potassium sulphate with 40% potassium) as nutritious source. The experiment was carried out as a completely randomized design (CRD) with factorial arrangement in three replications. Experimental factors included six levels of bacteria (Pseudomonas aeruginosa، Pseudomonas putida، three strains from contaminated regions Ahvaz، Sarakhs and Tehran and control)، three levels of fertilizers treatment (0 and 2 ton. ha-1 of NPK) and two levels of soil condition (sterile and non-sterile) at two times (30 and 60 days). Then، soil total organic carbon (TOC) as index for the degradation of normal hexadacane in samples was measured. The results showed that degradation of normal hexadecane in sterilized soil samples were higher than non sterilized soil samples. the highest degradation of normal hexadecane was observed in the presence of Sarakhs strain. The amount of degradation by this strain with nutritious source was 45% whereas this value was lower (one third) in the absence of NPK. Moreover، the results indicated that the amount of degradation by the bacteria increased with time. Biodegradation value in the presence of NPK was 4-fold higher compared to no-NPK treatment after 60 days.