ARS | Publication request: New bioactive fatty acids from vegetable oils

Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: October 20, 2007
Publication Date: October 26, 2007
Citation: Hou, C.T. 2007. New bioactive fatty acids from vegetable oils. Proceedings of 36th US Japan Natural Resources Food and Agricultural Panel. p. 261-266.

Technical Abstract: Twelve Mortierella species: M. alpina NRRL 6302, M. claussenii NRRL 2760, M. elongata NRRL 5246, M. epigama NRRL 5512, M. humilis NRRL 6369, M. hygrophila NRRL 2591, M. minutissima NRRL 6462, M. multidivaricata NRRL 6456, M. nantahalensis NRRL 5216, M. parvispora NRRL 2941, M. sepedonioides NRRL 6425, and M. zychae NRRL 2592 were screened for their production of arachidonic acid (AA) and dihomo-'-linolenic acid (DGLA). All of the strains tested produced AA and DGLA. The total fatty acid content of 125 mg/g cell dry weight (CDW) and fatty acid composition for AA (19.63%) and DGLA (5.95%) in the mycelia of M. alpina grown on glucose were compatible with those reported earlier by Takeno et al. (2005). The top five AA producers (mg AA/g CDW) were in the following order: M. alpina > M. zychae > M. hygrophila > M. minutissima > M. parvispora. The top five CDW productions were: M. multidivaricata > M. parvispora > M. humilis > M. zychae. And the top five species for total fatty acids production (mg /g CDW) were: M. alpina > M. parvispora > M. hygrophila > M. zychae > M. minutissima > M. epigama. In anticipation of a large excess of co-product glycerol from national biodiesel program, these 12 species were screened for their production of AA and DHLA from glycerol. All species tested grew on glycerol and produced AA and DGLA except M. nantahalensis NRRL 5216, which could not grow on glycerol. The amount of AA and DGLA produced are compatible with those obtained with glucose-grown mycelia. The top five AA producers (mg AA/CDW) from glycerol were in the following order: M. parvispora > M. claussenii > M. alpina > M. zychae > M. minutissima. The top five dry mycelia weights productions were: M. zychae > M. epigama > M. hygrophila > M. humilis > M. minutissima. And the top five species for total fatty acids production (mg /g CDW) were: M. claussenii > M. parvispora > M. minutissima > M. hygrophila > M. maltidivaricata. Judging from their AA production and yields of CDW, and total fatty acids from glycerol, we selected two species, M. alpina and M. zychae for further studies with glycerol substrate. Glycerol concentration of 0.5% to 4% produced the best cells dry weights and AA production for both strains. Higher substrate concentration inhibited the cells growth. The best temperature and rpm for both species on cells growth and AA production were at 28°C and 120 rpm. Effect of pH on the growth and AA content was studied from 5 to 7.5. M. zychae had an optimum pH for both the cell growth and the production of AA at around pH 6.0. At pH higher than 7.0, zychae cells still produce AA however, their mycelia weight were decreased. At lower pH media, the cells grow and produce AA at a slightly reduced value. The effect of pH was not significant with M. alpina at the pH ranges tested. Time course studies showed that the maximum cell growth and AA production for both species were at 6 days of incubation. Therefore, glycerol can be considered for industrial use in the production of AA and DGLA.