Fatty acid metabolism in a flexibacterium and its role in crustacean nutrition

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Documents

  • Pablo Intriago

    Research areas

  • PhD, Marine Science

Abstract

The total fatty acid content of an estuarine Flexibacter trip and the relative proportion of the constituent fatty acids were affected by growth temperature, aeration ( and salinity. The proportion of Cl6:lw5 the main fatty acid, did not change with temperature, but was produced in higher concentrations in
xhe aiMOu*t o{ shaking cultures. In contrast, the amount of both linoleic and linolenic acids varied with temperature and aeration. The concentration of Cl6:lw5 per mg of protein changed with temperature, whereas the concentrations of both polyunsaturates were relatively constant. Both the proportion and concentration of the polyunsaturates were markedly stimulated by increases in salinity, although total fatty acid per mg protein decreased with it. The highest concentration of fatty acid per mg of protein did not coincide with the highest percentage of polyunsaturated fatty acids (PUFAs), when Inp was grown in different carbon sources. Inp growing in glucose had the highest concentration of PUFAs per mg of protein.
Radio labelled acetate and palmitate were differentially incorporated into the fatty acids of Inp2 a variant of Inp. Addition of cAMP inhibited the incorporation of radioactive precursors into PUFAs. In contrast the antibiotic cerulenin inhibited the incorporation of radio labelled substrate acetate and variant into C16:1. This strongly suggests that lnp2 posseses both the anaerobic and aerobic pathway for UFAs synthesis. Whilst PUFAs were absent when another variant lnp3 was grown in media with an osmotic strength close to that of seawater, PUFAs were produced when Inp3 was grown in a high osmotic strength medium. Addition of cAMP to the high osmotic strength medium prevented PUFAs synthesis.
Artemia salina was grown to adulthood on diets consisting of bacteria, bacteria plus algae and algae only. Generally, there were no differences in survival between the diets. However, different diets reflected differences in the total dry weight. Addition of algae to the Inp3 diet increased PUFAs concentration per animal dry weight. It is suggested that Inp3 may be able to provide both PUFAs and exoenzymes, which assist in the digestion of algae.

Details

Original languageEnglish
Awarding Institution
  • University College of North Wales
Supervisors/Advisors
  • G Floodgate (External person) (Supervisor)
Thesis sponsors
  • British Council
Award date1990