Growth of Colpidium campylum in monoxenic batch culture

The population growth rate, as measured by changes in cell number or biomass, of Colpidium campylum monoxenically cultured on Aerobacter aerogenes was found to vary significantly among batch cultures using the same medium and temperature. The lowest estimates of cell number growth rate were found in cultures where late exponential phase cells were used as inocula. Under these conditions, biomass growth rate exceeded growth in cell numbers. When stationary phase cells were used as inocula, the opposite was true. Variation in growth rate measurements could be reduced by transferring cultures every 24 h, so that early exponential phase cells were used as inocula. The growth dynamics of Colpidium are discussed in terms of an ecological strategy for dealing with environmental patchiness.