ENERGETICS OF PSEUDOMONAS-CEPACIA G4 GROWTH IN A CHEMOSTAT WITH PHENOL LIMITATION

Analysis of the growth of Pseudomonas cepacia G4 on phenol in continuo us culture has been carried out. The data were checked for consistency using both available electron and carbon balances. Coupled with the c ovariate adjustment estimation technique, the best estimates for true biomass energetic yield, eta(max) and maintenance, m(e), were obtained when the carbon dioxide measurements were excluded. However, upon mak ing corrections to the gas measurements, the best estimates were the m aximum likelihood estimates (MLE) based on the complete data. The meth od therefore allows discrimination to be made between data. Also, simi lar estimates were obtained using Pirt's model based on the Monod appr oach and a modified form based on substrate uptake rate being the limi ting factor. For the aerobic growth of P. cepacia G4 on phenol, eta(ma x) = 0.417 and m(e) = 0.0513 h-1 were obtained when the CO2 data were excluded. When corrections were made to the gas measurements to take i nto account the dissolved CO2 and the effect of operating temperature, eta(max) = 0.432 and m(e) = 0-0684 h-1 were obtained. From the 95% co nfidence intervals, a maximum of about 38-47.5% of the energy containe d in phenol is incorporated into the biomass while the balance (52.5-6 2%) is evolved as heat with only a little energy needed for the mainte nance of the organism.