Carbon dating of bacteria
It is generally accepted that marine bacteria utilize labile, recently produced components of bulk dissolved organic matter.
This interpretation is based largely on indirect measurements using model compounds and plankton-derived organic matter.
Usually, dilute HCl (10% conc.) is used in this treatment.
It is added to the sample in a beaker which is placed on a hot plate and heated until slowly boiling.
Here, we present an assessment of the relative proportions of modern and older dissolved organic carbon (DOC) utilized by marine bacteria.
Bacterial nucleic acids were collected from both estuarine (Santa Rosa Sound, FL) and open-ocean (eastern North Pacific) sites, and the natural radiocarbon signatures of the nucleic acid carbon in both systems were determined.
Morphologies in the group have remained much the same for billions of years, and they may leave chemical fossils behind as well, in the form of breakdown products from pigments.
But many of these studies relied on only a few different detection methods.
Now, a team of researchers using special equipment at the MAX-lab in Lund, Sweden, has applied more than six different techniques to verify that tissues from inside a Cretaceous mosasaur humerus bone, which was kept in the Royal Institute of Natural Sciences of Belgium "for many years," consist of mosasaur and not microbial molecules. First, the investigators chemically removed the mineral matrix from the mosasaur bone, leaving behind the proteins and other biomolecules.
Bacterial nucleic acids from Santa Rosa Sound were significantly enriched in radiocarbon with respect to the bulk DOC and were similar to the radiocarbon signature of atmospheric CO2 at the time of sampling, indicating that these bacteria exclusively assimilate a modern component of the estuarine bulk DOC.
In contrast, bacterial nucleic acids from the oceanic site were enriched in 14C relative to the bulk DOC but depleted in 14C with respect to modem surface dissolved inorganic carbon (DIC) and suspended particulate organic carbon (POC(susp)).