Fatty acid methyl ester (FAME) analysis for monitoring Nocardia levels in activated sludge

The overall goal of this study was to evaluate the ability of fatty acid methyl ester (FAME) technology to quantify Nocardia levels in activated sludge samples. In order to distinguish Nocardia cells in activated sludge, fatty acids associated with N. amarae pure culture were determined and compared to fatty acid profiles of non-foaming activated sludge. Seven fatty acid peaks were observed for N. amarae cells grown in pure culture. Two of these seven peaks appeared to be unique to Nocardia when compared to the FAME profiles for the activated sludge sample and, therefore, can potentially serve as signature fatty acids for detecting and quantifying Nocardia in similar systems. In addition, we performed FAME analysis on mixed liquor samples containing various levels of N. amarae cells. Greater amounts of the signature fatty acids were extracted from the mixed liquors containing higher levels of Nocardia, and these amounts additionally correlated well with the conventional filamentous counting technique.