- Abstract Cell lines of Spirulina platensis and Porphyridium cruentum resistant to growth inhibition by the herbicide SAN 9785 had a significantly higher growth rate than their respective wild-type strains. These lines were also shown to overproduce γ-linolenic acid (GLA) and eicosapentaenoic acid (EPA), respectively, in the presence and absence of the inhibitor, as compared with wild-type cultures under similar conditions. The effect was most conspicuous in polar lipids. Thus, the proportion of GLA in the galactolipid (GL) fraction of the SAN 9785-resistant strain of S. platensis, SRS-1, increased in the absence of the inhibitor from 33.3% in the wild-type to 39.0%. Similarly, the proportion of EPA in the GL fraction of the resistant strain of P. cruentum, SRP, increased in the presence of the inhibitor from 29.1 to 45.4%.