FATTY ACID METHYL ESTER (FAME) ANALYSIS FOR MONITORING NOCARDIA LEVELS IN ACTIVATED SLUDGE

Analysis of fatty acid methyl esters (FAMEs) extracted from cellular membrane lipids presents exciting possibilities for monitoring and quantifying the abundance of NOCARDIA and possibly other organisms in activated sludge. We identified signature fatty acids unique to NOCARDIA by determining fatty acids associated with N. amarae. Two fatty acids (‘C19:1 alcoholω8’ and ‘SF3’) were identified as signature fatty acids for detecting and quantifying NOCARDIA in similar systems. In order to evaluate the ability of FAME technology to selectively quantify Nocardia levels in the mixed liquor samples, we extracted FAMEs from mixed liquor samples from various foaming and non-foaming full-scale treatment plants. Greater amount of the signature fatty acid (19:1 alcohol) was extracted from the mixed liquors containing higher levels of NOCARDIA. The peak areas of signature fatty acid in mixed liquor samples were closely correlated to the conventional filamentous counting technique. FAME profiles from chemostat culture of NOCARDIA showed that the distribution and quantity of the fatty acids were similar for two relatively short mean cell residence times; however the two of the seven fatty acids (16:0 and 19:1 Alcohol) were shifted at the higher cell residence time (4 days). This shift suggested that the FAME profile is dependent on the physiological state of the organism and it may be useful for monitoring the condition of organisms in activated sludge systems.