The nematocidic agent Corynebacterium paurometabolum was cultured in autoclaved suspensions of torula yeast. To determine the growth of the microorganism in the suspensions, a standard addition technique was developed; which could discriminate the optical density of the bacterial biomass and the suspended substrate absorbance. Consequently. the correction absorbance curves for each suspension and microorganism growth curves were obtained. The statistical analysis of the humid cell weight variable in the interval studied showed that a torula yeast suspension at 3% (w/v) is the most efficient choice for biomass production. (C) 2000 Elsevier Science Ltd. All rights reserved.