Actinomycetes degrade cellulose and solubilize lignin during composting. Changes in the diversity of the actinomycetal communities and the 16S rDNA copy numbers of actinomycetes were monitored by denaturing gradient gel electrophoresis (DGGE) and quantitative PCR (qPCR), respectively, during continuous thermophilic composting (CTC) and traditional composting (TC). qPCR indicated that the copy numbers from the CTC samples were 25-80% higher than those from the TC samples during similar phases of active composting and they were lower than 3 x 10(9) gene copies/g (dry weight) in the mature compost from both runs. DGGE showed a more diverse actinomycetal community in the CTC than in IC, averaging 16 bands as compared to 12 bands, at the post peak temperature phase. The study suggested that temperatures higher than 50 degrees C in CTC benefited the growth of actinomycetes. (C) 2010 Elsevier Ltd. All rights reserved.