Efficiency of the dispersion and differential centrifugation technique in the isolation of chitinolytic actinomycetes from soil

Actinomycetes were isolated from an acidic Brazilian soil under cerrado (savanna) vegetation, previously amended with chitin. The efficiency of two isolation techniques, the conventional dilution plate and the dispersion and differential centrifugation (DDC) procedures, were compared and a mathematical computer analysis of the results was made. The DDC technique gave counts about nine times greater than the conventional one. Analysis of the derivative curves suggested the presence of two distinct groups of actinomycetes on the isolation plates, one able to induce chitinolytic enzymes during amendment and the other whose initial activity was delayed. Major differences in results with different isolation procedures suggest a more subtle ecological role for these microbes in terms of their location in the soil environment.