Abstract:
Polyaromatic hydrocarbonic (PAH) air pollution through vehicular and industrial emission is a
highly concerned great threat in the modern world. The ability of bacteria, highly abundant in the
phyllosphere of polluted and urbanized areas to degrade these deposited PAH pollutants into
non-toxic levels was assessed and analyzed the concentrations of deposited PAH pollutants in
the phyllosphere. Leaf samples of four ornamental plants species (Ixorachinensis,
Evertamiadervaticata, Hibiscus rosa-sinensis and Amaranthus cruentus) were randomly
collected from five polluted and a less polluted area as the control to isolate the PAH degrading
phyllosphere bacterial species. Then plate assays, colorimetric methods and HPLC analysis were
used to determine the best PAH degrading bacteria and subsequently identified them up to
species level using molecular techniques. HPLC results revealed leaf phyllospheres of the
polluted areas had significantly higher phenanthrene and naphthalene concentrations compared
to the control site and phyllosphere bacterial population of the polluted areas were significantly
higher than that in the less polluted site. As per HPLC and colorimetric results, out of twenty
PAH degraders seven bacterial strains (Alcaligenes faecalis, Alcaligenes sp.11SO, Bacillus
cereus, Bacillus methylotrophicus, Serratia marcescens, Alcaligenes sp. BC and Alcaligenes sp.
GC)showed significantly higher PAH degradation abilities. Data indicates that, Alcaligenes
feacalis was the best naphthalene and phenanthrene degrader with 98% and 88 % degradation
abilities respectively. Phenanthrene and naphthalene concentrations high, phyllosphere of
polluted areas had significantly higher PAH degrading bacterial populations compared to the
control site. Out of seven phenanthrene and naphthalene degrading bacteria, Alcaligenes
feacalisis especially an efficient bioremediator, because of its multi PAH degrading ability. The
promising results of the present investigation will broaden the perspective of practical
application of the above bacterial strains at environmental sites where contamination is caused
by PAHs especially, phenanthrene and naphthalene. |
