MAINTENANCE REQUIREMENTS IN BACILLUS-SPHAERICUS 1593M UNDER DUAL SUBSTRATE LIMITATIONS ESTIMATED AT ZERO GROWTH-RATE IN A TOTAL CELL RETENTION CULTURE

The maintenance requirement(s) exhibited by Bacillus sphaericus 1593M was clearly established from the data on the steady state continuous c ultures wherein the growth yield was found to be increasing with incre ase in dilution rate (4). In the present study we have attempted to es timate the maintenance coefficient of B. sphaericus 1593M by achieving zero growth rate in a total cell retention culture (TCRC). Zero growt h rate was achieved at a cell density of 5.57 g l(-1) which remained c onstant reflecting a steady state in the TCRC. Based on the substrate flux calculations, maintenance coefficient was found to be 0.087 h(-1) . Further, using this data of maintenance coefficient, steady state ce ll density and substrate profiles in continuous cultures of B. sphaeri cus 1593M were predicted by simulation, which showed a close relations hip to that of the experimental data.