Particle Counter Determination of Bacterial Biomass in Seawater

The applicability of the Elzone particle counter to the determination of marine bacterial biomass was investigated. The biomass of bacterial pure cultures and a mixed natural population were followed by using the particle counter, a CHN analyzer, and an ATP analyzer. The particle counter showed the precise size distribution of number and volume of submicron-size particles in seawater. For the pure cultured bacterial strains, the conversion factor from volume to carbon is 0.209 mg of C per mm³, and for natural bacterial cells of >0.6 μm in diameter, it is 0.184 mg of C per mm³. It is recommended that 0.2 be used as the conversion factor for both pure cultured marine bacterial cells and natural bacteria from coastal and near-shore marine environments.