Measurement of carbon and nitrogen biomass, and biovolume from naturally derived marine bacterioplankton

摘要

Bacterial production often needs to be presented in carbon or nitrogen biomass. Conversions to such universal units are particularly necessary to interpret the data in terms of energy or material flow in relation to other trophic groups of organisms. For field applications, bacterial biomass is routinely estimated from cell concentrations or cell volumes (biovolume) with appropriate conversion factors. For the direct determination of a conversion factor, in principle, three independent parameters are measured; number of cells, biovolume of the cells, and biomass. Current methods for all of those three are subject to potential errors. Described here is a method that combines the acridine orange (AO) direct count method for cell enumeration, AO epifluorescence photomicrography for the biovolume measurement, and CHN analysis for C and N biomass. This method offers several improvements including bacterial cells are derived from natural seawater and grown in unsupplemented natural seawater; corrections are made for the bacterial cells passing through glass fiber GF/F filters; and biovolume measurement is calibrated with fluorescent microspheres of known diameters.