DETERMINATION OF BACTERIAL BIOVOLUME WITH EPIFLUORESCENCE MICROSCOPY - COMPARISON OF SIZE DISTRIBUTIONS FROM IMAGE-ANALYSIS AND SIZE CLASSIFICATIONS

A microscopic method for the determination of bacterial biovolume is presented using epifluorescence microscopy. The Microvid(R) system (LEITZ Co., Germany) combines direct observations of the microscopic picture with a data processing unit. This method is an easy way to obtain total values of bacterial biovolumes and mean biovolumes by measurements of lengths (diameters) of bacteria. Differentiations of rods into optimal size classes for evaluating bacterial volumes are not necessary. Thus, calculated data show the distribution pattern of bacterial lengths follows a logarithmic distribution function. A transformed function of this pattern is used to estimate the total biovolume. The individual contributions of cocci, rods and other bacteria to the overall biomass are discussed. These methods are used with an example of bacteria from Antarctic soils.