Can We Estimate Bacterial Growth Rates from Ribosomal RNA Content?
Molecular Ecology of Aquatic Microbes
Several studies have demonstrated a strong relationship between the quantity of RNA in bacterial cells and their growth rate under laboratory conditions. information on the activity of natural bacterial communities, and in particular on growth rate. interpretable information, the relationship between RNA content and growth rate must be well-understood. In particular, a requisite of such applications is that the relationship must be universal among bacteria, or alternately that the relationship
... t the relationship can be determined and measured for specific bacterial taxa. It may be possible t o use this relationship to provide However, if this approach is to provide reliably The RNA-growth rate relationship has not been used to evaluate bacterial growth in field studies, although rRNA content has been measured in single cells and in bulk extracts of field samples taken from coastal environments. These measurements have been treated as probable indicators of bacterial activity, but have not yet been interpreted as estimators of growth rate. primary obstacle to such interpretations is a lack of information on biological and environmental factors that affect the RNA-growth rate relationship. The In this paper, the available data on the RNA-growth rate relationship in bacteria will be reviewed, including hypotheses regarding the regulation of RNA synthesis and degradation as a function of growth rate and environmental factors; i.e. the basic mechanisms for maintaining RNA content in proportion t o growth rate. An assessment of the published laboratory and field data, the current status of this research area, and some of the remaining questions will be presented.