Bioaugmentation of the thermophilic anaerobic biodegradation of cellulose and corn stover

- Two mixed, stable thermophilic cellulolytic consortia were enriched.
- The consortia enhanced the methane yield by 22-24%.
- Predominant orders were Thermoanaerobacterales and Clostridiales.
- The 4 most abundant strains contributed to only half of the augmentation.
- Strains in low abundance play significant role.

Two stable, thermophilic mixed cellulolytic consortia were enriched from an industrial scale biogas fermenter. The two consortia, marked as AD1 and AD2, were used for bioaugmentation in laboratory scale batch reactors. They enhanced the methane yield by 22-24%. Next generation sequencing method revealed the main orders being Thermoanaerobacterales and Clostridiales and the predominant strains were Thermoanaerobacterium thermosaccharolyticum, Caldanaerobacter subterraneus, Thermoanaerobacter pseudethanolicus and Clostridium cellulolyticum. The effect of these strains, cultivated in pure cultures, was investigated with the aim of reconstructing the defined cellulolytic consortium. The addition of the four bacterial strains and their mixture to the biogas fermenters enhanced the methane yield by 10-11% but it was not as efficient as the original communities indicating the significant contribution by members of the enriched communities present in low abundance.