Using light scatter signal to estimate bacterial biovolume by flow cytometry.

Background: In the past decade, flow cytometry has become a useful and precise alternative to microscopic bacterial cell counts in aquatic samples. However, little evidence of its usefulness for the evaluation of bacterial biovolumes 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 flow cytometry and epifluorescence microscopy, respectively, in order to establish a relationship between light scattering and cell volume.

Results: With the arc-lamp flow cytometer, forward angle light scatter (FALS) was related to cell size in both the starved strains and natural communities, although regression parameters differed. We tested the predictive capacity of the FALS verous cell size relationship in a bacterial community from the North Sea. That analysis showed that a reliable bacterial biovolume prediction 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 measurements. It is possible to establish a generally applicable model derived from natural bacterial assemblages for flow cytometric estimation of bacterial biovolumes by light scatter.