Environmental Engineering Reference
In-Depth Information
Chapter 13
Root and Shoot Peroxidase Activity in
Festuca
arundinacea
in Light Oil-Contaminated Soil
Zahra Ghaffari, Sahar Shademan, Zahra Sobhani-Damavandifar
and Dariush Minai-Tehrani
Abstract
Peroxidases are a group of enzymes that occur especially in plant cells.
They are classified as oxido-reductases and are given the official EC number 1.11.1.
For many of these enzymes the optimal substrate is hydrogen peroxide, but others
are more active with organic hydroperoxides such as lipid peroxides. Peroxidases
can contain a heme cofactor in their active sites, or redox-active cysteine or seleno-
cysteine residues. Toxic molecules such as superoxide and hydroxide radicals can
be found in cells due to the presence of oxygen. These are byproducts of aerobic
respiration. They are eliminated by a number of enzymes present inside the cell
such as peroxidases. Some oil-producing countries may encounter the risk of soil
pollution by oil, during transportation, extraction and refining of crude oil. Oil-
contaminated soil can be hazardous to plants and soil microorganisms. Among the
plants, grasses such as
Festuca arundinacea
(Tall fescue) and legumes have high
potential on removal of oil from contaminated soil. In the process of phytoremedia-
tion of crude oil, some morphological, enzymatic and physiological changes were
observed in plants. In this study, the effect of light crude oil (5 % v/w) in soil on the
activity of peroxidase was studied and compared with control. Our results showed
that in both roots and shoots, the K
m
and V
max
of the enzyme were changed. The
contaminated soil caused delay of germination and chlorosis in plants. In the con-
taminated soil, the K
m
of root peroxidase was determined to be about 55.5 µM while
it was 91 µM in control. The V
max
of root's enzyme was 2 and 6 nmol/mg protein/
min in contaminated soil and control, respectively. The K
m
of enzyme in shoots was
determined to be about 36 and 42 µM in contaminated soil and control, respectively,
while the V
max
in control was about 1.4 nmol/mg protein/min and it decreased to
