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Biotechnological Studies for the Production of Arachidonic Acid from Mortierella Alpina

Nisha, A. (2009) Biotechnological Studies for the Production of Arachidonic Acid from Mortierella Alpina. PhD thesis, University of Mysore.

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Abstract

Mortierella alpina CBS 528.72, an oleaginous fungus and the most promising source of arachidonic acid (ARA) was exploited for production of this nutraceutically and pharmaceutically important polyunsaturated fatty acid (PUFA). Several physical and chemical factors were investigated for their effect on biomass buildup, oleaginicity and ARA yield. Results of the study indicated that these physical and chemical parameters had a significant effect on biomass, total lipid and ARA yield in this strain. Scale up study was carried out at 15L fermentor level subsequent to optimization under shake flask conditions. One factor at a time (OFAT) and Response surface methodology (RSM) proved to be efficient strategies for maximizing ARA yield in M. alpina. Furthermore the use of corn solids as a cheaper alternative for yeast extract reduced the cost of the process significantly. Lipid extraction efficacy varied considerably with the mode of extraction, solvent used and pretreatment of biomass. Mass transfer in intact cells of M. alpina was hindered by hard natural membrane resulting in reduced lipid extraction. HCl and enzyme pretreatment significantly increased the percentage of ruptured cells thereby improving mass transfer of solutes and lipid extraction. Use of low temperature and 2, 3, 5- Triphenyl tetrazolium chloride enabled the selection of arachidonic acid hyper producers from innumerable putative mutants. In spite of the set backs, random mutagenesis still proved effective in isolating arachidonic acid hyper-producing mutants of M. alpina. The safety of feeding M. alpina biomass was evaluated by acute and subchronic toxicity studies in Wistar rats which indicated a favourable preclinical profile of the biomass in safety evaluation. Cloning, sequencing and phylogenetic analysis of 5 desaturase indicated that M. alpina 5 desaturase was phylogenetically related to algal, slime mould and fungal desaturases with a conserved HPGG motif and three characteristic histidine boxes at the cytochrome b5 region. These 5 desaturases were phylogenetically distinct from the animal 5 desaturases which formed a strong cluster in itself indicating a later divergence than the fungal and plant counterparts. In view of the above facts Mortierella alpina single cell oil can be accepted as a biotechnological product fulfilling the key roles in the supply of nutraceutically and pharmaceutically relevant polyunsaturated fatty acids essential for infant and geriatric nutrition.

Item Type: Thesis (PhD)
Uncontrolled Keywords: polyunsaturated fatty acids, Mortierella alpina, arachidonic acid, nutraceuticals
Subjects: 500 Natural Sciences and Mathematics > 07 Life Sciences > 04 Microbiology > 04 Fungi
600 Technology > 08 Food technology > 18 Processed foods > 04 Functional foods
Divisions: Food Microbiology
Depositing User: Food Sci. & Technol. Information Services
Date Deposited: 01 Mar 2011 11:53
Last Modified: 28 Dec 2011 10:21
URI: http://ir.cftri.com/id/eprint/9961

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