Degradation properties of Rhizobium petrolearium on different concentrations of crude oil and its derivative fuels

The degradative efficiency of the recently identified species, Rhizobium petrolearium, on crude oil, diesel, petrol and kerosene was analysed in this study in order to assess its potential as a bioresource in environmental remediation and to investigate the effect of pollutant concentration on degradation efficiency. The identity of the isolate was confirmed by 16S rRNA sequencing and the variation in crude oil and fuel concentration during the biodegradation assay were measured using gas chromatography. Crude oil and the fuels were readily biodegradable at both single and tenfold concentrations, with petrol being the most degraded by the end of the study. Pollutant concentration was shown to affect degradation properties. At 1% concentration, the hydrocarbon compounds were almost completely degraded (99.3 to 99.6%) by day 5, but at the 10% concentration, the degradation level ranged from 31.8 to 63.8% on day 21. Crude oil and diesel oil showed the lowest biodegradation rates at 1% concentration and had half-lives of 0.68 and 0.64 days, respectively. Crude oil and kerosene were the most poorly degraded at 10% concentration with half-lives of 39.61 and 19.80 days, respectively. The C9 – C17 aliphatic fractions were generally the most readily utilised. This study presents a description of the biodegradation capabilities of R. petrolearium against crude oil and its derivative fuels and provides data regarding the possible role of this isolate in the development of bioaugmentation-focused bioremediation systems.