Effect of centrifugation on ATP content of soil extracts and microbial cell samples

It has been studied the effect of centrifugation as stress agent on measurements of microbial activity in soils and in cultures of Rhizobium hedysari strain. For this reason the ATP content in soil extracts and ATP content, dehydrogenase and urease activities of microbial cultures were measured. Further, the same parameters were monitored during the stationary or exponential phase of cellular cultures. Centrifugation of bacterial suspension, more than soil extracts, decreased the ATP content, the same occur for the dehydrogenase activity whereas increased urease activity in bacterial suspensions. The strongest influence was found on ATP content and urease activity than dehydrogenase activity when cellular suspensions were centrifuged during stationary phase and exponential growth.