Total heat balance study of anaerobiosis inTubifex tubifex (M�ller)

Abstract

1. Simultaneous measurement of rates of heat production, oxygen uptake and release of volatile fatty acids (VFA), acetic and propionic acid, byTubifex tubifex (Muller) showed that the steady-state anaerobic heat production as calculated from the release of anaerobic end-products, acetic and propionic acid, is similar to the direct measured anaerobic heat production under oxic as well as anoxic conditions. 2. The anaerobic heat production of lowPO2 acclimated animals amounts to 20–30% of the steady-state total aerobic plus anaerobic heat production measured on highPO2 acclimated animals under air saturated conditions. 3. The agreement between the observed and calculated rates of anaerobic heat production suggest that no anaerobic endproducts are accumulated in the animals under steady-state conditions and further that acetic and propionic acid are the only anaerobic end-products of quantitative importance. 4. The production and subsequent release of all anaerobic end-products is interpreted as representing a mechanism by whichTubifex and other facultative anaerobes maintain steady-state anaerobiosis and a simultaneous high calorific efficiency in milieus where extended periods of environmental anoxia are frequently experienced.