True and Apparent Yields and Maintenance Coefficient and Their Significance on Fermentation Kinetics

Abstract

Yield based on substrate (Y_x/s) or oxygen consumption (Y_x/o) is a very important parameter. This parameter indicates how efficient a fermentation is. At the same time it is very closely related with the maintenance coefficient (m). By means of yield and maintenance coefficient it is possible to estimate the proportion of energy that cells consume in biomass and metabolites synthesis and the proportion of energy that allows the cells to maintain their capability for their biological performance. Unfortunately the maintenance coefficient is not normally considered due to difficulties in its estimation and therefore the assessment yield could be disturbed. A method for the estimation of the former parameters is proposed in this work. The method was applied to a submerged fermentation with Lactobacillus rhamnosus and compared with results previously obtained for solid state fermentation of sugar cane and citrus residues with Candida utilis and Aspergillus niger respectively.