Adaptation of a rapid and economical microcentrifugation method to measurethymidine and leucine incorporation by soil bacteria

A simplified method using centrifugation and microcentrifuge tubes instead of filtration to measure bacterial activity using thymidine or leucine inco rporation, originally used in aquatic habitats, has been adapted for soil. A final step employing hot NaOH to solubilize macromolecules before adding scintillation fluid was necessary to achieve the same incorporation rates a s those in the filtration technique. The microcentrifugation technique has several advantages, including being less costly, less laborious and having lower zero-time controls. The samples could also be stored for at least 2 w eeks after incorporation was stopped by adding TCA. The microcentrifugation technique would therefore be most useful when a large number of samples, s ome with very low incorporation rates, are to be studied, for example, when studying bacterial community tolerance. (C) 2001 Elsevier Science Ltd. All rights reserved.