The celular concentration (X) of Aspergillus awamori NRRL 3112 in 4 batch cultivation with different concentrations of the carbon source, is directly relacionated with the mass of the 2 N sodium hidroxide (M) consumed on order to maintain the pH 5. It was determined a linear correlation between the log of the 2 variables, log X = -0,79 + 0,67 log M, with r = 0,997, which permit a imediate approach of X on a basis of M, in a course of a fermentation.