Analysis of diesel hydrocarbon decomposition using efficient indigenous bacterial isolate: Bacterial growth and biodegradation kinetics

Industrialization and urbanization have increased the demand for petroleum hydrocarbons; hence the likelihood of contamination of air, soil, and water bodies increases. The survival and biodegradation capabilities of fifteen bacterial isolates were tested in a harsh diesel environment. The bacteria were isolated from soil samples and identified by 16S rRNA gene sequencing. The biodegradation capability of isolates was performed in batch experiments, and diesel degradation analyses were conducted on gas chromatography-mass spectroscopy (GC-MS). The results revealed that only two bacterial isolates (A1 and E5) sufficiently consumed diesel hydrocarbons as a carbon-based energy source. 16S rRNA sequencing identified both isolates as Bacillus genera. An average of 60% of 3% (v/v) diesel was degraded in about 16 hours. Bacillus sp. E5 strain could degrade about 72% and 68% heavier compounds of C24 and C26. The Monod kinetic model for Bacillus sp. E5 utilizing diesel as a substrate showed maximum specific bacterial growth rate (μmax) as 0.1131 hr-1 at 1%, while 0.1287 hr-1 for 3% diesel. Results suggest that the isolated bacterial strain Bacillus sp. E5 has bioremediation potential and can be used as an alternative method for cleaning contaminated petroleum hydrocarbon field sites for sustainable development.