Determination of the Monod substrate saturation constant for microbial growth

Abstract

Methods used to determine the Monod substrate saturation constant for microbial growth are surveyed. The preferred and most accurate method is to assay the concentrations of growth rate-limiting nutrients in steady-state continuous cultures. But, this is not always possible due to the lack of sufficiently sensitive assay methods or due to high nutrient fluxes in rapidly growing cultures. It is suggested that an acceptable and simple alternative method for aerobic microorganisms is to measure initial oxygen uptake rates during growth in the presence of different initial concentrations of growth rate-limiting nutrient. It is important in this method that the microbial cells are taken from rapidly growing cultures and are suspended in a medium permitting growth.