Morphology and eicosapentaenoic acid production by Monodus subterraneus UTEX 151

The optimum culture conditions of Monodus subterraneus UTEX 151 for eicosapentaenoic acid (EPA) production were at 25 °C, initial pH 7.0 and continuous illumination at 10 Klux light. The gas chromatographic data indicated that the fatty acid composition 20:5n-3 was predominant, at approximately 31%. In addition, 16:1, was the major monounsaturated fatty acid, while the 22:6n-3 was absent. Cultivation in 20 mM sodium acetate slightly enhanced the content of EPA from 31% up to 34% of the total fatty acids. Light micrographs of M. subterraneus UTEX 151 showed that the cell shape changed from spherical to ellipsoidal, as cell maturity was achieved. When the cells were in stationary phase, these became elongated spindle-shaped ellipses. TEM data demonstrated lipid body formation occurring in the thylakoid space of the chloroplast. Lipid body size varied with growth phase stage and they finally formed round clusters. The ultrastructure of M. subterraneus UTEX 151 vegetative cells of early and stationary growth stage showed the presence of chloroplasts, with many lipid bodies in the cell. Starch granules and lipid bodies occupied an-equal volume in the cell.