Abstract Members of the
Sphingomonas genus are often isolated from
petroleum-contaminated
soils due to their unique
abilities to degrade
polycyclic aromatic hydrocarbons (PAHs), which are important for in situ
bioremediation. In this study, a combined phenotypic and genotypic approach using
streptomycin-containing medium and
Sphingomonas -specific
PCR was developed to isolate and identify culturable
Sphingomonas strains present in
petroleum-contaminated
soils in the Shenfu
wastewater irrigation zone. Of the 15
soil samples examined, 12
soils yielded yellow
streptomycin-resistant colonies. The largest number of yellow
colony-forming units (CFUs) could reach 105 CFUs g-1
soil. The number of yellow CFUs had a significant positive correlation (p < 0.05) with the ratio of PAHs to total
petroleum hydrocarbons (TPH), indicating that
Sphingomonas may
play a key
role in degrading the PAH fraction of the
petroleum contaminants at this site. Sixty yellow colonies were selected randomly and analyzed by colony
PCR using
Sphingomonas -specific primers, out of which 48 isolates had
PCR-positive signals. The 48 positive amplicons generated 8 distinct
restriction fragment length polymorphism (
RFLP) patterns, and 7 out of 8 phylotypes were identified as
Sphingomonas by
16S rRNA gene sequencing of the representative
strains. Within these 7
Sphingomonas strains, 6
strains were capable of using fluorene as the sole
carbon source, while 2
strains were phenanthrene-degrading
Sphingomonas. To the best of our
knowledge, this is the first
report to evaluate the relationship between PAHs
contamination levels and culturable
Sphingomonas in environmental samples.