Construction of a stable microbial community with high cellulose-degradation ability.

We bred a microbial community capable of degrading rice straw with high efficiency. The microbial community degraded more than 60% of rice straw within 4 days at 50 degrees C. The high stability of the community's degradation ability was demonstrated by its tolerance of being subcultured several times in medium with/without cellulosic material, being heated to 95 degrees C, and freezing at -80 degrees C. The community degraded both nonsterilized and sterilized substrate; and its degradation ability was not affected by pH changes in the medium (initial pH 5-9). PCR-denaturing gradient gel electrophoresis (DGGE) analyses based on 16S rDNA fragments showed that the community structure remained constant after multiple subcultures extending over 2 years. DNA sequence analyses of DGGE bands indicated the coexistence of both aerobic and anaerobic bacteria in the community.