Growth characteristics and oxidative capacity of Acetobacter aceti IFO 3281: implications for L-ribulose production.
We studied the growth characteristics and oxidative capacities of Acetobacter aceti IFO 3281 in batch and chemostat cultures. In batch culture, glycerol was the best growth substrate and growth on ethanol occurred only after 6 days delay, although ethanol was rapidly oxidized to acetic acid. In continuous culture, both glycerol and ethanol were good growth substrates with similar characteristics. Resting cells in a bioreactor oxidized ribitol to L-ribulose with a maximal specific rate of 1.2 g g(-1) h(-1)). The oxidation of ribitol was inhibited by ethanol but not by glycerol. Biomass yield (Y(SX); C-mmol/C-mmol) on ethanol and glycerol was low (0.21 and 0.17, respectively). In the presence of ribitol the yield was somewhat higher (0.25) with ethanol but lower (0.13) with glycerol, with respectively lower and higher CO(2) production. In chemostat cultures the oxidation rate of ribitol was unaffected by ethanol or glycerol. Cell-free extract oxidized ethanol very slowly but not ribitol; the oxidative activity was located in the cell membrane fraction. Enzymatic activities of some key metabolic enzymes were determined from steady-state chemostat with ethanol, glycerol, or ethanol/glycerol mixture as a growth limiting substrate. Based on the measured enzyme activities, metabolic pathways are proposed for ethanol and glycerol metabolism.
Kylmä
A K
AK
Laboratory of Bioprocess Engineering, Department of Chemical Technology, Helsinki University of Technology, PO Box 6100, 02015 HUT, Finland.
Granström
T
T
Leisola
M
M
D019342:Acetic Acid / Q000378:metabolism; D000091:Acetobacter / Q000201:enzymology / Q000254:growth & development* / Q000378:metabolism*; D018533:Biomass; D019149:Bioreactors; D001711:Biotransformation; D002245:Carbon Dioxide / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D002474:Cell-Free System / Q000378:metabolism; D003470:Culture Media / Q000737:chemistry; D004798:Enzymes / Q000378:metabolism; D000431:Ethanol / Q000378:metabolism; D005990:Glycerol / Q000378:metabolism; D007700:Kinetics; D010084:Oxidation-Reduction; D010101:Oxygen Consumption; D010429:Pentoses / Q000378:metabolism*; D012255:Ribitol / Q000378:metabolism*; D019802:Succinic Acid / Q000378:metabolism
D003470:Culture Media; D004798:Enzymes; D010429:Pentoses; D002245:Carbon Dioxide; D000431:Ethanol; D012255:Ribitol; C100182:ribulose; D019802:Succinic Acid; D005990:Glycerol; D019342:Acetic Acid