Polyunsaturated Fatty Acids (Pufas) Of Mucor Sp. With Special Reference To Gamma Linolenic Acid (Gla)

Mamatha, S. S. (2009) Polyunsaturated Fatty Acids (Pufas) Of Mucor Sp. With Special Reference To Gamma Linolenic Acid (Gla). PhD thesis, University of Mysore.

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Abstract

Lipids are one of the main classes of macronutrients required for human growth and nourishment. In order to obtain native isolate for GLA production, soil samples were collected from various habitats for screening the Mucor spp. in nutrient rich medium. Based on the external morphology and microscopic observation Mucor spp. were isolated, compared with the standard cultures and comparisons were also made with the Gilman manual of soil fungi These isolates were screened for their oleagenicity both qualitatively and quantitatively, staining with Sudan black-B and gravimetric method respectively. All the selected Mucor spp. and standard cultures were cultivated on submerged fermentation to study the growth characteristics, lipid and GLA contents. The results indicated that the highest biomass, lipid and GLA content were observed in M. rouxii CFR-G15. The presence of GLA in the lipid of this isolate was confirmed by the mass spectrometric method. By using gene specific primers, 18S rRNA and D6 DES genes were amplified by PCR technique. Nucleotide sequences of 18S rRNA and D6 DES genes exhibited 98% homology with M. rouxii ATCC 24905 (accession no.AF117923 and AF296076) respectively, suggesting taxonomic identity. A nucleotide sequences determined in this study was submitted to the GenBank and obtained the accession numbers EU927296 and EU526025 for 18SrRNA and D6 DES genes respectively. Cultivation conditions were selected for GLA production by optimizing appropriate selection of both physical and chemical parameters such as pH, temperature, aeration, inoculum concentration, medium composition, carbon and nitrogen sources, C:N ratio combination, different vegetable oils, and different concentration of minerals in growth media. It was concluded in this study that pH 5.5, temperature at 28±2°C, glucose, yeast extract & ammonium nitrate as carbon and nitrogen sources and C:N ratio of 60 produced maximum biomass, lipid production and GLA content in this strain. A CCR design was used for PDF created with pdfFactory Pro trial version www.pdffactory.com 22 optimizing the levels of carbon and nitrogen sources to maximize the GLA production by RSM. By using different solvent extraction, this study concluded that chloroform and methanol in 2:1 ratio gave maximum recovery of lipid. The M. rouxii CFR-G15 was subjected to mutation through physical and chemical methods (UV, EMS & NTG) and after several screening, a metauxotroph was obtained and this amino acid marker was used for hybridization studies to obtain stable hybrids. Putative hybrids were qualitatively characterized for high lipid and GLA production. Hybrid CFR-HyG 9 showed highest GLA content of 23.34 ±1.23 % in 42.46±2.41% of lipid content which was 1.5 fold higher than the parent culture in basal medium. Thus, the various experiments carried out in this study, ultimately aimed to increase the biomass, total lipid content and maximizing the GLA production. Plants beings the conventional sources of essential fatty acids have some limitations/disadvantages that can be over ruled by microorganisms. Hence microorganisms of GRAS status are now being exploited genetically as sources of PUFAs and tailored for maximum productivity. The potential also exists in selecting the microbial strains producing large proportions of lipid that can meet the present market demand of omega-6 fatty acids, the GLA for nutritional and pharmaceutical supplementation.

Item Type:	Thesis (PhD)
Uncontrolled Keywords:	Lipids, GLA production, microorganisms
Subjects:	600 Technology > 08 Food technology > 19 Lipids-oils/fats 500 Natural Sciences and Mathematics > 07 Life Sciences > 04 Microbiology
Divisions:	Food Microbiology
Depositing User:	Food Sci. & Technol. Information Services
Date Deposited:	01 Mar 2011 09:28
Last Modified:	22 Dec 2016 11:33
URI:	http://ir.cftri.res.in/id/eprint/9949

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