L(Ο©)-Lactic acid production was enhanced in the are generally spherical in shape. Such pellets are subject culture of Rhizopus oryzae using mycelial flocs formed by to mass transfer limitations which produce solute gradiaddition of 3 g/L mineral support and 5 ppm polyethylene ents through the spheres. Mycelium at the center of the oxide. By addition of the mineral support, an electrostatic pellet become nutrient limited as the pellet increases in repulsion between mycelia increased by 3.5-fold comsize; growth is eventually continued in a shell of limited pared to that of mycelia, which allowed a dispersed growth of R. oryzae in the early growth phase. In conventhickness at the surface of the pellet (Pirt, 1967). In tional culture the morphology of R. oryzae is that of a cases of filaments and pellets, mass transfer limitations pellet-like cake, however, when support and polyethylene are commonly encountered and growth of the mycelium oxide are added to the culture, the morphology of R.
on the impeller or on the electrodes hampers optimal oryzae takes on a cotton-like appearance. The formation control of the process.
of these cotton-like mycelial flocs was induced by the addition of 5 ppm polyethylene oxide into a 14 h culture There has been much progress in the study of mold containing the mineral support before the formation of molecular biology in recent years but the advancements the conventional pellet morphology. The cotton-like flocs in culture techniques of mold has proceeded at a slow were also formed in cultures grown in a fermentor. This pace. The reason for this is that it is difficult to control morphology allowed effective mass transfer inside the the morphology of the mold which will lead to a high flocs and effective fluidity of culture broth in the reactor. L(Ο©)-Lactic acid concentration produced by mycelial flocs reactor performance. Phenomenon of flocculation may in fermentor, with the support and polyethylene oxide, be one of methods to culture mycelia (Mill, 1964). The was 103.6 g/L with the yield of 0.86 using 120 g/L of other method may be a dispersion of mycelia in the glucose as the substrate for this cultures without both, culture broth. We reported that the mineral support the concentration was 65.2 g/L. It demonstrates that cotdispersed mycelial pellets in the culture broth and emulton-like mycelial flocs are the optimal morphology in the culture of R. oryzae.