Premium
Enhancement of L (+)‐lactic acid production using mycelial flocs of Rhizopus oryzae
Author(s) -
Kosakai Yuuko,
Soo Park Yong,
Okabe Mitsuyasu
Publication year - 1997
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/(sici)1097-0290(19970805)55:3<461::aid-bit1>3.0.co;2-a
Subject(s) - mycelium , rhizopus oryzae , fermentation , polyethylene , chemistry , lactic acid , morphology (biology) , food science , pellet , botany , materials science , biology , bacteria , organic chemistry , composite material , genetics
Abstract 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.