Tj. Boyd et Af. Carlucci, USE OF A H-3 LABELED SUBSTRATE TO MEASURE MICROBIAL BIODEGRADATION INMARINE WATERS, Journal of microbiological methods, 20(1), 1994, pp. 11-22
A method is described in which a high specific activity (SA) H-3-label
ed substrate was used to measure microbial biodegradation of p-cresol
in coastal marine waters. [2,6-H-3]p-cresol with a SA of 11 Ci mmol(-1
) was added to marine waters collected off Southern California. After
short incubations of 12 h, subsamples were filtered to collect bacteri
al cells, respired (H2O)-H-3 and H-3-labeled biodegradation intermedia
tes were collected, and residual [2,6-H-3]p-cresol was isolated using
C-18 solid phase extraction columns. Activity in each of these fractio
ns was used to calculate biodegradation kinetics. Filter effects, subs
trate adsorption, and extraction efficiency were determined with forma
lin treated abiotic controls. The method has broad applicability and s
ince H-3-labeled substrates are commercially available with about thre
e orders of magnitude greater SA than for C-14-labeled compounds, the
method can detect biodegradation rates at extremely low levels of targ
et organics. Also, the method allows for use of smaller sample volumes
and, as a result, smaller amounts of radioactive waste are produced.
In environments where contamination is present and its concentration c
an be determined, isotopic dilution can be calculated and radioactivit
y can be related to total contaminant concentration. The method has br
oad applicability for assessing the kinetics of p-cresol (and other H-
3-labeled phenols) biodegradation in areas of contamination.