الفهرس 
Review of LiteratureOnly 14 pages are availabe for public view
Abstract
Development of novel technologies for the remediation
of industrial and hazardous wastes is increasing rapidly.
Particular attention is being focused upon the usage of
biological treatment systems. Aerobic and anaerobic
microbial treatment processes have been successfully
employed in the destruction and/or removal of organic
compounds, inorganics and metals.
Cyanide is a known toxic chemical produced through
anthropogenic activities and industries that use ore leaching,
electroplating, steal production, plastics, and synthetic fibers.
In this study, the cyanobacterial cyanase enzyme was
targeted to cytosol and overexpressed in Chlamydomonas
reinhardtii via Agrobacterium tumefaciens mediated coculivation transformation method in order to establish a
synthetic pathway for cyanide degradation. Transgenic C.
reinhardtii algae containing the necessary genes for the novel
pathway were generated. Variable amounts of RNA were
detected by qRT-PCR. Simultaneous over-expression of
cyanase would ultimately result in the formation of CO2 and
NH3 from cyanide.
Summary
133
Biochemical and physiological analyses were performed
under cyanide stress conditions using C. reinhardtii
transgenic for evaluating the impact of the novel pathway in
algae:
A) CYN-overexpressor and wild type C. reinhardtii
were allowed to grow under different
concentrations of cyanide (25, 50, 100,150 and 200
mg/L). CYN transgenic strain showed the specific
activity of cyanase enzyme, which was obviously
more than their corresponding activities in wild
species. The study demonstrated that the ability of
Cr.CYN genetically modified strains to grow at
high concentrations of cyanide compared to the
unmodified strain, especially at 150 and 200 mg/L.
B) The study showed that cyanide had an inhibitory
effect on mean growth rate, relative growth rate,
generation time and number of recycling of both
wild and transgenic samples as compared to the
control.
C) To evaluate the percentage of removal of cyanide
in both microalgae, transgenic type and wild type
was treated with different concentration of cyanide
(25, 50, 100, 150 and 200 mg/L), the modified
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134
Cr.CYN strains showed high cyanide removal
efficiency compared to the unmodified strain. At
the lowest concentration of cyanide 25 mg/L, the
percentage of cyanide removal was reached 100%
after 24 hours for the genetically modified alga,
compared to the wild type reached 100% after 48
hours. The non-modified alga was unable to grow
under high concentration of cyanide 200 mg/L.
D) The study showed the ability of genetically
modified alga to produce high level of ammonia
compared to wild type.
E) In addition to the decrease in the pigment content
of the wild type was highly observed as compared
with the genetically modified organism. The
percentage of reduction in chlorophyll a was
reached to 37.3% in the transgenic alga compared
to 75.82% in the non-transgenic alga. Also, the
percentage of reduction in chlorophyll b was
reached 35.75% in the transgenic alga compared to
81.36% in the wild type.
F) The study showed increases in cyanase activity as
concentration of cyanide increase especially, in
case of transgenic type. The maximum activity was
indicated in presence of 100 mg/l cyanide it
Summary
135
reached eight folds more than wild type activity at
the same cyanide concentration.
G) Also, some factors are taken in consideration like
different pH, contact time. Moreover, percentage of
cyanide removal by transgenic type two folds more
than wild type at awide range of pH.
Results of this study provide an effective eco-friendly
phycoremediation system for cyanide detoxification using
transgenic micro algae.