Using light scatter signal to estimate bacterial biovolume by flow cytometry

Background: In the past decade, flow cytometry has become a useful and prec ise alternative to microscopic bacterial cell counts in aquatic samples. Ho wever, Little evidence of its usefulness for the evaluation of bacterial bi ovolumes has emerged in from the literature. Methods: The light scattering and cell volume of starved bacterial strains and natural bacterial communities from the Black Sea were measured by now c ytometry and epifluorescence microscopy, respectively, in order to establis h a relationship between light scattering and cell volume. Results: With the are-lamp now cytometer, forward angle light scatter (FALS ) was related to cell size in both the starved strains and natural communit ies, although regression parameters differed. We tested the predictive capa city of the FALS verous cell size relationship in a bacterial community fro m the North Sea. That analysis showed that a reliable bacterial biovolume p rediction of a natural bacterial community can be obtained from FALS using a model generated from natural bacterial community data. Conclusions: Bacterial biovolume is likely to be related to FALS measuremen ts. It is possible to establish a generally applicable model derived from n atural bacterial assemblages for flow cytometric estimation of bacterial bi ovolumes by light scatter. (C) 2001 Wiley-Liss, Inc.