TUBERCULOSTEARIC ACID AS A MEANS OF ESTIMATING THE RECOVERY (USING DISPERSION AND DIFFERENTIAL CENTRIFUGATION) OF ACTINOMYCETES FROM SOIL

A dispersion/differential centrifugation (DDC) procedure was used to recover actinomycetes from a sandy soil. The efficiency of the procedure in recovering actinomycetes was monitored using tuberculostearic acid (TBSA). To measure TBSA in soils and in the DDC extracts, an acid methanolysis procedure, used routinely for the extraction of fatty acid methyl esters from pure cultures, was modified to include a preliminary wash in chloroform:methanol. The modified methanolysis procedure extracted 104% of the TBSA from biomass added to soil. The recovery of actinomycetes, estimated from the recovery of TBSA (10-methyloctadecanoic acid) in the soil extract, was 41+/-1.5% of that present in the whole soil. This compares favourably with values obtained for the recovery from sandy soils of biomarkers representative of the total biomass, namely phospholipid and adenosine triphosphate. The techniques outlined in this paper demonstrate the usefulness of the DDC procedure in enhancing the recovery of TBSA containing actinomycete propagules from soil and provides a simple chemical analysis by which different recovery procedures can be compared.