ISSN:
0006-3592
Keywords:
mycelial flocs
;
mineral support
;
polyethylene oxide
;
L(+)-lactic acid
;
Rhizopus oryzae
;
Chemistry
;
Biochemistry and Biotechnology
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Biology
,
Process Engineering, Biotechnology, Nutrition Technology
Notes:
L(+)-Lactic acid production was enhanced in the culture of Rhizopus oryzae using mycelial flocs formed by addition of 3 g/L mineral support and 5 ppm polyethylene oxide. By addition of the mineral support, an electrostatic repulsion between mycelia increased by 3.5-fold compared to that of mycelia, which allowed a dispersed growth of R. oryzae in the early growth phase. In conventional culture the morphology of R. oryzae is that of a pellet-like cake, however, when support and polyethylene oxide are added to the culture, the morphology of R. oryzae takes on a cotton-like appearance. The formation of these cotton-like mycelial flocs was induced by the addition of 5 ppm polyethylene oxide into a 14 h culture containing the mineral support before the formation of the conventional pellet morphology. The cotton-like flocs were also formed in cultures grown in a fermentor. This morphology allowed effective mass transfer inside the flocs and effective fluidity of culture broth in the reactor. L(+)-Lactic acid concentration produced by mycelial flocs in fermentor, with the support and polyethylene oxide, was 103.6 g/L with the yield of 0.86 using 120 g/L of glucose as the substrate for this cultures without both, the concentration was 65.2 g/L. It demonstrates that cotton-like mycelial flocs are the optimal morphology in the culture of R. oryzae. © 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 55: 461-470, 1997.
Additional Material:
8 Ill.
Type of Medium:
Electronic Resource
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