Biodegradation of used engine oil by novel strains of Ochrobactrum anthropi HM-1 and Citrobacter freundii HM-2 isolated from oil-contaminated soil

Abstract

Used engine oil (UEO) constitutes a serious environmental problem due to the difficulty of disposal off or reuse. Ten bacterial strains with biodegradation potential were isolated from UEO-contaminated soil sample using enrichment technique. Two strains which exhibited the highest degradation %, 51 ± 1.2 and 48 ± 1.5, respectively, were selected. Based on the morphological, biochemical characteristics and 16S rRNA sequence analysis, they were identified as Ochrobactrum anthropi HM-1 (accession no: KR360745) and Citrobacter freundii HM-2 (accession no: KR360746). The different conditions which may influence their biodegradation activity, including UEO concentration (1–6 %, v/v), inoculum size (0.5–4 %, v/v), initial pH (6–8), incubation temperature (25–45 °C), and rotation speed (0–200 rpm), were evaluated. The optimum conditions were found to be 2 % UEO, 2 % inoculum size, pH 7.5, incubation temperature 37 °C, and 150 rpm. Under the optimized conditions, strains HM-1, HM-2, and their mixture efficiently degraded UEO, they achieved 65 ± 2.2, 58 ± 2.1, and 80 ± 1.9 %, respectively, after 21 days of incubation. Biodegradation of UEO was confirmed by employing gas chromatography analysis. Gamma radiation (1.5 kGy) enhanced the degradation efficiency of irradiated bacterial mixture (95 ± 2.1 %) as compared to non-irradiated (79 ± 1.6 %). Therefore, strains HM-1 and HM-2 can be employed to develop a cost-effective method for bioremediation of used engine-oil-polluted soil.

Effects of cadmium and lead on the biodegradation of diesel-contaminated soil

“…Heavy metal tolerance test during biodegradation of crude oil investigated by Tiku et al [8] showed that some crude oil degraders were tolerant to cadmium at concentrations of 20, 100, 200, 250, and 300 µg/ml. The presence of lead and cadmium in the concentration ranges of 0.21-0.15 mg/kg and 2.10-1.2 mg/kg respectively were also reported by Ibrahim [34] in the biodegradation of used engine oil by novel strains of Ochrobactrum anthropi HM-1 and Citrobacter freundii HM-2.…”

Isolation, identification, and characterization of diesel‐oil‐degrading bacterial strains indigenous to Changqing oil field, China

“…All of the strains were capable of using diesel oil as the sole carbon source. Compared with previous investigations , for example, Hong reported that there were nine strains isolated from the oil‐contaminated soil in Korea; and Ibrahim reported that ten strains were isolated from oil‐contaminated soil; Saadoun reported that there were five strains isolated from the soil samples that had been exposed to the crude petroleum oil spills; Kumar reported that there were four fluoranthene degrading strains isolated from the petroleum sludge. In addition, there were 12 strians isolated on this study, so the isolation efficency is relatively higher.…”

Isolation and Screening of Diesel Degrading Bacteria from Ship Dismantling Facility at Tanjungjati, Madura, Indonesia

“…Olawale, et al [8] state that bioremediation has many advantages for detoxification of toxic substances because it is an environmentally friendly and simple method. Bioremediation depends on the ability of microorganisms to degrade diesel pollutants [9]. Some bacteria isolated from diesel contaminated areas have the ability to produce enzymes for degrading and utilizing diesel as carbon and energy source [10].…”