Bacterial production in the Delaware Bay estuary estimated from thymidine and leucine incorporation rates

Abstract

The thymidine and leucine methods were examined and used to estimate bacterial production in the Delaware Estuary. During growth experiments that minimized grazing on bacteria, conversion factors for both thymidine and leucine were initially high and then rapidly decreased to values lower than commonly-used factors (2.0 x 10 super(18) cells mol super(-1) for thymidine). The low thymidine conversion factors may have been due to ( super(3)H)thymidine incorporation into protein, which was 72% of total incorporation in untreated samples from the estuary. Addition of glucose reduced the leucine conversion factor from 7.4 to 3.6 x 10 super(16) cells mol super(-1) and the thymidine conversion factor from 1.53 to 0.68 x 10 super(18) cells mol super(-1). The thymidine and leucine approaches gave similar estimates of bacterial production in the Delaware Bay (20 to 70 x 10 super(6) cells l super(-1)h super(-1)).