الفهرس 
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Abstract
Abstract
Lipid production in terms of oil percentage and fatty acid
composition of Nostoc paludosum, Anabaena torulosa and Phormidium
ambiguum, which were identified morphologically by light microscope and
genetically via 16S rRNA gene sequence amplifications were studied in the
control state and in response to 4 different stress factors. Salinity stress ranging
from 50 to 250mM NaCl, nitrogen and phosphorus stress regimes (50% NO3-
N, 50% PO4-P of BG11 media) and lastly the collective effect of all the 3
stressors combined. The results indicated that there were changes in the
physiological behavior under all these different kinds of stress which are also
illustrated genetically. Oil extraction by Hexane-isopropanol method was
performed for analysis of lipid content. The results revealed that the optimum
lipid production for N. paludosum, A. torulosa and P. ambiguum was
observed at 250mM NaCl stress, 50% phosphorus and at 100mM NaCl stress,
respectively. Gas chromatography mass spectrometry (GC/MS) analysis of
fatty acid composition revealed that the main constituent of these fatty acids
was classified as suitable for biodiesel due to their long methyl ester chains.
These results were explained genetically using RAPD-PCR technique which
revealed the appearance and disappearance of some bands. Subsequently, this
led to change in DNA sequence which in turn led to DNA polymorphism
recording 47.06%, 41.25% and 57.89% for N. paludosum, A. torulosa and P.
ambiguum respectively. These 4 treatments generated some genetic mutations
which induced changes in the DNA sequence which showed physiologically
in the lipid profiles of the 3 species. Nostoc paludosum and P. ambiguum had
higher SFAs, while A. torulosa had higher PUFAs values. The DNA banding
pattern indicated that stress of nitrogen, phosphorus, salinity and combined
stress caused more changes compared to control. Thus, the stress changes that
were observed in the physiological studies were confirmed genetically.