Acetate production from lactose by Clostridium thermolacticum and hydrogen-scavenging microorganisms in continuous culture--effect of hydrogen partial pressure.
The effect of the addition of hydrogen-consuming microorganisms on the metabolism of Clostridium thermolacticum was studied. By growing this bacterium in continuous culture at 58 degrees C, on 29 mmol lactose l(-1) (10 gl(-1)) in the feed, with the H2-consuming microorganisms Methanothermobacter thermoautotrophicus and Moorella thermoautotrophica, the volumetric productivity of acetate was increased up to 3.9 mmol l(-1)h(-1) at a dilution rate of 0.058 h(-1). This was about three times higher than the maximal acetate volumetric productivity quantified when C. thermolacticum was cultivated alone. In the consortium, C. thermolacticum was the only species able to metabolize lactose; it produced not only acetate, but also hydrogen, carbon dioxide and lactate. The other species of the consortium were growing on these by-products. Meth. thermoautotrophicus played an important role as a very efficient hydrogen scavenger and decreased the hydrogen partial pressure drastically: hydrogen was converted to methane. Moor. thermoautotrophica converted lactate as well as hydrogen and carbon dioxide into acetate. As a consequence, lactose was efficiently consumed and the only organic product in the liquid phase was acetate.
Collet
Christophe
C
Laboratory for Environmental Biotechnology (LBE), Swiss Federal Institute of Technology Lausanne (EPFL), Station 6, CH-1015 Lausanne, Switzerland.
Gaudard
Olivier
O
Péringer
Paul
P
Schwitzguébel
Jean-Paul
JP
D000085:Acetates / Q000378:metabolism*; D001419:Bacteria / Q000378:metabolism*; D001673:Biodegradation, Environmental; D019149:Bioreactors / Q000382:microbiology*; D018929:Cell Culture Techniques / Q000379:methods*; D048013:Acetivibrio thermocellus / Q000378:metabolism*; D018920:Coculture Techniques / Q000379:methods; D019605:Euryarchaeota / Q000378:metabolism*; D006859:Hydrogen / Q000378:metabolism*; D007785:Lactose / Q000378:metabolism*; D011312:Pressure
D000085:Acetates; D006859:Hydrogen; D007785:Lactose