Abstract
Soil pollution, particularly of petroleum hydrocarbons and lead contamination, has become increasingly concerned due to rapid urbanization and industrial development. Bioremediation of petroleum hydrocarbon pollution using microorganisms is a promising solution due to the absence of secondary contamination. In this study, two bacterial isolates (B-7 and B-10), with distinctive colony characteristics, were screened from petroleum contaminated soil collected in Zhuhai, Guangdong Province, China. Using 16S rRNA sequencing technique and biochemical analyses, B-7 and B-10 were identified to be closely related to Achromobacter denitrificans, and Mycolicibacterium phocaicum N4, respectively. Petrol degrading rates of the two isolates were determined by UV-visible spectrophotometer in this study. With consideration of recovery rate and background evaporation rate, in the absence of lead, in a five-day interval study, the petrol degradation rate of B-7 and B-10 was observed at approximately 2.4g petrol/L for both isolates. Co-contamination with lead at 1, 5, 10 and 20ppm significantly inhibited petrol degrading potential of both isolates, with B-10 demonstrated significantly higher lead tolerance. Future studies are needed to evaluate the effects of other abiotic factors, such as pH, temperature, nutrient contents and concomitant exposure to other pollutants and biotic factors, such as microbial community, on the petroleum hydrocarbons degrading efficiency of these isolates.
Highlights
Due to rapid development of the economy, the demand of petrol has been increasing steadily in the past few decades
By 16S rRNA sequencing and biochemical analyses, B-7 was found to show the highest homology to Achromobacter denitrificans; while B-10 was found to have 99.71% sequence homology to Mycolicibacterium phocaicum N4
Significant inhibition in growth and petrol degradation rate was observed in B-7 and B-10 at 1ppm and 5ppm lead, respectively, indicating B-10 exhibited higher tolerance to lead exposure
Summary
Due to rapid development of the economy, the demand of petrol has been increasing steadily in the past few decades. It was estimated that more than 600,000 tons of petrol are released to the environment, threatening health of humans and our ecosystems [3,4]. Yu et al [5] and Shen [6] reported that in each year, an additional 100,000 tons of soils in China are polluted by petrol. Once soils are polluted by petroleum hydrocarbons, the efficiency on nutrient absorption by the root system of plants will be affected, inhibiting the growth of vegetation, thereby resulting in a reduction of crop yield, which significantly affects the livelihood of farmers [7,8]. Oil contamination may spread as petroleum hydrocarbons infiltrate into underground water systems or transfer with
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