After five cycles of enrichment, 1 ml of the culture broth was serially diluted and plated on 1.5% agar MBSM plates, and incubated for 7 d. Four hundred microliters of diesel oil were sprayed on the surface of each plate (20 ml MBSM) to obtain a thin layer. Each colony with a different morphology was characterized for petroleum hydrocarbon degradation in MBSM supplemented with 2% diesel oil as the carbon source.