Screening of a microbial consortium for selective degradation of lignin from tree trimmings.

To acquire microbial consortia with effectively precedent degradation of lignin, samples obtained from rotten trunks, rotten stumps and soil near it were screened and isolated after generations of subculture. The dynamic change illustrated that their community structures were affected by pH and tended to be stable after 6 days' cultivation. The desired one, named DM-1, was gained through successive cultivation for over 5 generations, whose high selectivity in lignin degradation was observed within 16 days' cultivation (SV = 2.78). Meanwhile, a remarkable reduction in the fiber crystallinity of tree trimmings (10.35%) resulted from the bio-degradation of DM-1, displayed a greater exposure of cellulose by selective removal of lignin. The diversity analysis of DM-1 was investigated by PCR amplification and 16S rDNA sequencing, indicated that mesorhizobium, cellulosimicrobium, pandoraea, achromobacter and stenotrophomones were the predominant genera. Furthermore, fungi (3 strains), bacteria (4 strains) and actinomycetes (5 strains) constituted 12 strains in total were gained by plate isolation from DM-1.