Petroleum is potentially toxic to living organisms,
and there are worldwide efforts to develop methods
for bioremediation of petroleum-contaminated soils. Phytoremediation
is an effective method to reduce the concentration
of petroleum in soils, and plant growthpromoting
rhizobacteria (PGPR) play an important role in
the phytoremediation. Two PGPR,
Pseudomonas aeruginosa
SLC-2 and
Serratia marcescens
BC-3, were isolated
from the rhizophere of
Echinochloa
grown in petroleumcontaminated
soil. These isolates showed capacities for
1-aminocyclopropane-1-carboxylate (ACC) deaminase activity,
indole acetic acid production, siderophore synthesis,
and the degradation of petroleum. The ACC deaminase
activity of SLC-2 and BC-3 was 2.52 ± 0.03 µmol α-KA
(mg Pr∙h)
-1 and 38.52 ± 0.37 µmol α-KA (mg Pr∙h)
-1,
respectively. On the other hand, when the concentration of
L-Trp increased, the IAA synthesis of BC-3 also increased,
while the synthesis of SLC-2 did not change significantly.
The ability of synthesized siderophore of SLC-2 was much
higher than that of BC-3. The petroleum degradations of
SLC-2 and BC-3 increased 4.78 and 7.36 %, respectively.
The pot experiment of oat was performed to evaluate the
plant growth-promoting abilities of SLC-2 and BC-3.
Compared with non-inoculated controls, the height and
fresh weight of stems increased (23.64 and 42.57) % and
(16.98 and 28.3) %, respectively, whereas the length and
fresh weight of roots also increased (10.34 and 20.84) and
(24.13 and 43.11) %, respectively, when inoculated with
SLC-2 and BC-3. The results indicated that
P. aeruginosa
SLC-2 and
S. marcescens BC-3 can serve as promising
microbes for increasing plant growth in petroleum-contaminated
soil to improve the phytoremediation efficiency.
