Environmental Engineering Reference
In-Depth Information
used subject for phytoremediation experiments due to easy growing and dense root
system (Binet et al.
2000
), so we chose it as a subject for this study. Some herba-
ceous species such as clover, alfalfa also have relatively dense root systems, and
are often used in phytoremediation studies, so that our second experimental plant
pattern became alfalfa (
Medicago caucasica
L.).
In addition, the plant must be suitable for soil and climatic conditions at the site
and must be able to tolerate the contaminant. This was the reason for choosing the
third object—wormwood (
Artemizia fragrans
L.), which is one of the widespread
inhabitants of petroleum contaminated Absheron soils.
Plants were propagated different ways based on their peculiarities. Perennial
ryegrass was propagated from seeds germinated in the dark at room temperature
on a sterile filter paper soaked in 5 ml of sterilized deionized water. Germination
occurred after 4 days.
Alfalfa and wormwood were propagated vegetatively as shoots from a grown
plant. Propagation had been carried out via hydroponics until seedlings emerged the
roots, and then replanted to experimental pots.
2.3 Microorganisms
The soil microbial inoculum was obtained from the consortia of hydrocarbon-de-
grading bacteria maintained in Azerbaijan Culture Collection (AZCC). Consortia
include
Rhodobacter fascians
AZCC 1501,
Alcaligenes feacalis
AZCC 1164,
A.
feacalis
AZCC 1165,
A. eutrophus
AZCC 1171,
Bacillus subtilis
AZCC 1288 and
B.
subtilis
AZCC 1289. All these strains were selected as high hydrocarbon degrading
strains with an ability to synthesize biosurfactants. Biosurfactants were isolated by
acid precipitation following Das et al. (
2008
)
3
Results and Discussion
The Absheron oil composition is specific compard to other types of petroleum. The
C/H ratio is 84/12 which means a large amount of non-saturated hydrocarbons.
It has much of cycloparaphines, and less alkanes and aromatic compounds which
might influence on its utilization by microbes and plants. First, we analyzed the
fraction content of the petroleum used in our study. The sample we selected was
received from Bibi-Eybat terrestrial oil field, which is characterized as light petro-
leum with priority of light short-chained fractions (Table
7.1
).
Selected microorganisms stored in AZCC were initially isolated from the typical
Absheron petroleum contaminated soil and proved highly adaptive to such type of
petroleum hydrocarbons to utilize.
Three different plants (ryegrass, alfalfa and Artemisia), a microbial inoculant
containing the association of hydrocarbon degrading and biosurfactant producing
