DNA Synthesis as a Measure of Bacterial Productivity in Seagrass Sediments

Abstract

B a c t e r ~a l growth rates In sedlments have been calculated fiom measurements of the rate of lncolporatlon of trltlated thymldlne Into d e o x y r ~b o n u c l e ~c acld (DNA) T h e dllutlon of Isotope In DNA w a s used to estlmate the s u m of the pools of thymldlne In the sedlment and of other cellular precursors of t h y m ~d ~n e In DNA Growth rates of bacterla In the surface zone of seagrass bed sedlrnents v a r ~e d from 3 7 X 10' cell d l v ~s ~o n s h -' g -' dry weight of sediment on a hot autumn day to 3 3 X 10" cell d l v l s ~o n s h -' g ' In w ~n t e r By c o m b ~n ~n g growth rate measurements uslng the ~s o t o p e d ~l u t ~o n procedure with biomass measurements ~t IS now p o s s ~b l e to obtaln redsondbly r e l ~a b l e estimates of b a c t e r ~a l product~vity In sedlments