Frequency of Dividing Cells as an Estimator of Bacterial Productivity

Abstract

The frequency of dividing bacterial cells (FDC) possibly can be used to predict growth rates of natural aquatic bacterial assemblages. The relationship between FDC and growth rate in bacteria from southern-temperate, coastal marine waters was examined using incubation under conditions of manipulated nutrient availability and exclusion of bacterivores. The regression of the natural logarithm of bacterial instantaneous growth rate (.mu.) on FDC resulted in a better fit than regression of untransformed .mu. on FDC. The regression equation was 1n .mu. = 0.299FDC - 4.961. The coefficient of variation for predicted 1n .mu. at mean FDC was 7%. The range of FDC-estimated bacterial instantaneous generation times for coastal Georgia [USA] waters was 12-68 h, and range of calculated bacterial production rates was 0.6-17.6 mg C .cntdot. m-3 .cntdot. h. Unresolved problems of and suggested improvements on the FDC method of predicting growth rate are discussed.