In order to study the inhibitory effect of the partial pressure of carbon dioxide (pCO(2)) on bacterial cellulose (BC) production by Acetobacter xylinum subsp. sucrofermentans BPR3001A, the BC concentration, oxygen consumption rate, viable cell concentration, and ATP content of the cells were investigated during cultivation in a 50-l jar fermenter sparged with air containing 10% (v/v) CO2. A high pCO(2) (0.15-0.20 atm) reduced the BC yield, BC production rate per unit volume of broth (the volumetric BCPR), and viable cell concentration. However, it enhanced the oxygen consumption rate and the ATP content per viable cell, and consequently the BC production rate per viable cell (the specific BCPR). Thus, a high pCO(2) reduced BC production due to a reduction of cell growth and not by inhibiting BC biosynthesis. A possible reason for the reduction of the BC yield arising from a high pCO(2) is the dissipation of substrate for excess ATP generation.