Assessment of Microbial Fatty Acid Analysis for Quantifying Mixed Culture Biomass During Batch Growth

This paper considers microbial fatty acid (MFA) as a parameter for monitoring kinetics of changing biomass levels in dynamic environmental systems. Although there is no question that MFA and biomass levels are directly linked, the research literature suggests that the proportionality constant is variable. Thus, controlled batch cultivation experiments were performed to test the hypothesis that total MFA (TMFA) is a consistent biomass representation. The hypothesis was tested with measurement comparisons to the more conventional biomass parameters of dry weight and protein production. Experimental results supported the validity of TMFA analysis as a measurement method for assessing biomass growth kinetics under dynamic mixed culture conditions. Although MFA composition did change over the course of batch cultivation, TMFA remained directly proportional to biomass dry weight and protein production. In a comparison of absolute TMFA levels derived from two distinct protocols of MFA extraction, significant differences in the TMFA yield were observed. Therefore, MFA data need to be clearly referenced to the applied method of analysis.