66] Geosmin production

Abstract

This chapter describes the open-loop stripping system (OLSA) method for the determination of geosmin in cyanobacterial cultures. Geosmin (trans-l,l0-dimethyl-trans-2-decalol) is an earthy smelling substance produced by actinomycetes and cyanobacteria. The method widely used for geosmin determination is the closed-loop stripping analysis (CLSA) system developed for analysis of trace organics in water. The selection of appropriate equipment materials is of primary importance in avoiding contamination. The materials recommended are glassware, polytetrafluoroethylene (PTFE), and stainless steel. All the materials must be thoroughly washed with appropriate solvents before building the system. Between each run the sintered glass filter must be cleaned with chromic acid. The stripping conditions described are found to be optimal for determining the total amount of geosmin in a cyanobacterial culture. Because geosmin is present both in the culture medium and in the cells, stripping of the whole culture is required to determine the total concentration of the compound. The results so far indicate that the OLSA method at 60° is adequate for determining the total amount of geosmin in cyanobacterial cultures.