Growth condition optimization for docosahexaenoic acid (DHA) production by Moritella marina MP-1

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2013-01-01
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Kautharapu, Kumar
Rathmacher, John
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Jarboe, Laura
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Chemical and Biological Engineering

The function of the Department of Chemical and Biological Engineering has been to prepare students for the study and application of chemistry in industry. This focus has included preparation for employment in various industries as well as the development, design, and operation of equipment and processes within industry.Through the CBE Department, Iowa State University is nationally recognized for its initiatives in bioinformatics, biomaterials, bioproducts, metabolic/tissue engineering, multiphase computational fluid dynamics, advanced polymeric materials and nanostructured materials.

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The Department of Chemical Engineering was founded in 1913 under the Department of Physics and Illuminating Engineering. From 1915 to 1931 it was jointly administered by the Divisions of Industrial Science and Engineering, and from 1931 onward it has been under the Division/College of Engineering. In 1928 it merged with Mining Engineering, and from 1973–1979 it merged with Nuclear Engineering. It became Chemical and Biological Engineering in 2005.

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1913 - present

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  • Department of Chemical Engineering (1913–1928)
  • Department of Chemical and Mining Engineering (1928–1957)
  • Department of Chemical Engineering (1957–1973, 1979–2005)
    • Department of Chemical and Biological Engineering (2005–present)

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The marine organism Moritella marina MP-1 produces the polyunsaturated fatty acid docosahexaenoic acid (DHA). While the basic metabolic pathway for DHA production in this organism has been identified, the impact of growth conditions on DHA production is largely unknown. This study examines the effect of supplemental carbon, nitrogen and salts, growth temperature and media composition and pH on DHA and biomass production and the fatty acid profile. The addition of supplemental nitrogen significantly increased the overall DHA titer via an increase in biomass production. Supplemental glucose or glycerol increased biomass production, but decreased the amount of DHA per biomass, resulting in no net change in the DHA titer. Acidification of the baseline media pH to 6.0 increased DHA per biomass. Changes in growth temperature or provision of supplemental sodium or magnesium chloride did not increase DHA titer. This organism was also shown to grow on defined minimal media. For both media types, glycerol enabled more DHA production per biomass than glucose. Combination of these growth findings into marine broth supplemented with glycerol, yeast extract, and tryptone at pH 6.0 resulted in a final titer of 82 ± 5 mg/L, a nearly eightfold increase relative to the titer of 11 ± 1 mg/L seen in the unsupplemented marine broth. The relative distribution of other fatty acids was relatively robust to growth condition, but the presence of glycerol resulted in a significant increase in myristic acid (C14:0) and decrease in palmitic acid (C16:0). In summary, DHA production by M. marina MP-1 can be increased more than fivefold by changing the growth media. Metabolic engineering of this organism to increase the amount of DHA produced per biomass could result in additional increases in titer.

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This is a manuscript of an article from Applied Microbiology and Biotechnology 97 (2013):2859, doi: 10.1007/s00253-012-4529-7. Posted with permission. The final publication is available at Springer -Verlag Berlin Heidelberg via http://dx.doi.org/10.1007/s00253-012-4529-7.

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Sun Jan 01 00:00:00 UTC 2012
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