A SPECTROFLUOROMETRIC METHOD FOR THE DETERMINATION OF TOTAL BACTERIALCOUNTS IN ENVIRONMENTAL-SAMPLES

We propose a spectrofluorimetric method for the determination of the c ounts and biomass of microbial cells in natural water, mud and soil sa mples. The method is based on the use of the fluorescent dye, fluoresc amine, which reacts specifically with proteins and amine acids of micr obial cells. The method allows the determination of cell numbers in th e range 10(6) cells/ml. At lower cell counts (below 10(6) cells/ml) of bacteria in oligotrophic waters, the samples had to be concentrated 2 0 to 50 fold. Heterogenous materials (bottom deposits, soil) required preliminary processing, such as sonication, dilution and filtration. M odel experiments with cell suspensions from a pure culture demonstrate d a strong relationship between fluorescence intensity and cell concen tration. A comparison of the results of direct counts with those obtai ned by the spectrofluorimetric method showed good correlation between the two. The proposed method has the advantage of rapidity and of the absence of subjective factors.