[Show abstract][Hide abstract] ABSTRACT: Development in the strain and the fermentation process of Hansenula polymorpha was implemented for the production of gamma-linolenic acid (GLA, C18:3 delta 6,9,12), which is an n-6 polyunsaturated fatty acid (PUFA) and has been reported to possess a number of health benefits. The mutated delta 6-desaturase (S213A) gene of Mucor rouxii was expressed in H. polymorpha under the control of the methanol oxidase (MOX) promoter. Without utilization of methanol a high cell-density culture of the yeast recombinant carrying the delta 6-desaturase gene was achieved by fed-batch fermentation using glycerol-limited conditions. The delta 6-desaturated products, octadecadienoic acid (C18:2 delta6,9), GLA and stearidonic acid (C18:4 delta6,9,12,15), accumulated at high levels under the derepression condition. The GLA production was also optimized by adjusting specific growth rates. The results show that the specific growth rate affected both lipid content and fatty acid composition of the GLA-producing recombinant. Among the various specific growth rates studied, the highest GLA concentration, which was at of 697 mg/l, was obtained in the culture with the specific growth rate of 0.08 /h. Interestingly, the fatty acid profile of the yeast recombinant bearing the Mucor delta 6-desaturase gene was similar to that of blackcurrant oil with both containing similar proportions of n-3 and n-6 essential fatty acids.
Preview · Article · Nov 2010 · Journal of Microbiology and Biotechnology
[Show abstract][Hide abstract] ABSTRACT: Gamma-linolenic acid (GLA, C18:3Δ6,9,12) is an n-6 polyunsaturated fatty acid (PUFA) that has been used for the alleviation and treatment of a number of symptoms and diseases.
Increasing GLA demand has led to a search for alternative producers and potential strategies for GLA production. Based on
the successful performance of Hansenula polymorpha, a methylotrophic yeast, as a “cell factory” for the production of valuable bioproducts, a bioprocess development approach
was implemented for GLA production in the recombinant yeast carrying the mutated Δ6-desaturase gene of Mucor rouxii. Using a substrate-feeding strategy under glycerol-limited conditions, the physical-chemical variables during the fed-batch
fermentation of the recombinant H. polymorpha were optimised for GLA production through response surface methodology using a Box-Behnken design. The medium composition,
including yeast extract and trace elements, and dissolved oxygen tension (DOT) were targeted. We found that DOT was the most
effective variable for enhancing GLA yield. These results also suggest that the optimum conditions for GLA production are
28 % saturation of DOT, 1 g L−1 of yeast extract and 3.6 mL L−1 of the Pichia trace metals 1 (PTM1).
–medium composition–dissolved oxygen tension–response surface methodology
Preview · Article · Apr 2010 · Chemical Papers- Slovak Academy of Sciences