Abstract: A group of cellulose degrading microbial flora (Xc) was screened from sullage,forest soil,cow manure and composted wheat straws with the technology of regularly altering the regeneration method during incubation on the modified PCS culture medium.The flora showed a stable and strong capability of degrading cellulose.About 81%,41%,25% and 40% of the cellulose in filter paper,absorbent cotton,wheat straw and cow manure,respectively,was degraded with 100 mL of Xc at 37 ℃ in 120 hours under static culture.In decomposing filter paper,its CMC enzyme activity peaked up to 104.5 and 95.3 U·mL^-1,on D5 and D7,at 37 and 28 ℃,respectively.Xc could be inoculated into culture media ranging in pH from 5 to 9,however,in the end of incubation the final pH of the medium tended to be neutral.The Xc cellulose-decomposing activity may last more than 22 days as long as supply of substrates continues.Xc is very stable in structure.Its main DNA bands remained unchanged as is demonstrated by comparison of 16S rDNA with the DGGE method of Xc from different time periods of the culture.

Key words: cellulose degradation, microbial flora, constant temperature, screening20