“…Two principal lines of evidence used to support rRNA as an indicator of current activity originate from earlier studies testing how rRNA scales with growth rate. First, total RNA and rRNA content correlate well with growth rate for a handful of microbes in pure culture, over a wide range of growth rates under balanced growth conditions (that is, growing in an unchanging environment) (Schaechter et al, 1958;Neidhardt and Magasanik, 1960;Rosset et al, 1966;Koch, 1970;Kemp et al, 1993;Kerkhof and Ward, 1993;Poulsen et al, 1993;Wagner, 1994;Bremer and Dennis, 1996;Ramos et al, 2000). Second, decreased rRNA content is associated with decreased growth rate for some organisms growing under specific nutrient-limiting conditions (Mandelstam and Halvorson, 1960;Davis et al, 1986;Kramer and Singleton, 1992;Tolker-Nielsen et al, 1997).…”