GROWTH AND ENERGY-CONSERVATION IN BATCH CULTURES OF PYROCOCCUS-FURIOSUS

Growth of Pyrococcus furiosus was studied in batch cultures with cellobiose, maltose and pyruvate as limiting substrates. Fermentation mass balances of all conversions were complete. These data suggested that the pathway for conversion of the disaccharides is essentially the same. The molar growth yields on maltose and cellobiose were about equal (+/-50 g cell dry weight (cdw) per mol disaccharide). The molar growth yield on pyruvate was +/- 6.3 g cdw mol(-1). Growth yields were influenced by the hydrogen partial pressure. When P. furiosus was co-cultured with a methanogen a yield of 56 g cdw mol(-1) disaccharide and 8.6 g cdw mol(-1) pyruvate was obtained. When the data were interpreted according to the proposed pyroglycolytic pathway, the calculated Y-ATP values were different for the various pH(2) conditions, suggesting that an additional energy conserving site may be present in the pathway.