Effect of Trace Metals
Flask cultures were performed using trace metals including Zn2+, Mn2+, and Fe2+ to investigate the effect of each metal on cell growth and pigment production and the results are shown in Fig. 5. Of these three metals, Fe2+ showed the strongest stimulatory effect on red pigment production. In the case of Zn2+, Bau and Wong [19] reported that pigment production by a mutant M. purpureous N11S was promoted by 5 × 10-5 M of zinc while mycelial growth was significantly inhibited. However, its relationship was reversed in our experiment. This result may be attributed to strain specificity .