Thermophilic enrichment of microbial communities in the presence of the ionic liquid 1‐ethyl‐3‐methylimidazolium acetate

Aims

The aim of the study was to develop an approach to enrich ionic liquid tolerant micro‐organisms that efficiently decompose lignocellulose in a thermophilic and high‐solids environment.

Methods and Results

High‐solids incubations were conducted, using compost as an inoculum source, to enrich for thermophilic communities that decompose switchgrass in the presence of the ionic liquid 1‐ethyl‐3‐methylimidazolium acetate (C2mim]OAc]). Ionic liquid levels were increased from 0 to 6% on a total weight basis incrementally. Successful enrichment of a community that decomposed lignocellulose at 55°C in the presence of 6% C2mim]OAc] was achieved, when the C2mim]OAc] level was increased stepwise from 2% to 4% to 5% to 6%. Pyrosequencing results revealed a shift in the community and a sharp decrease in richness, when thermophilic conditions were applied.

Conclusions

A community tolerant to a thermophilic, high‐solids environment containing 6% C2mim]OAc] was enriched from compost. Gradually increasing C2mim]OAc] concentrations allowed the community to adapt to C2mim]OAc].

Significance and Impact of the Study

A successful approach to enrich communities that decompose lignocellulose under thermophilic high‐solids conditions in the presence of elevated levels of C2mim]OAc] has been developed. Communities yielded from this approach will provide resources for the discovery of enzymes and metabolic pathways relevant to biomass pretreatment and fuel production.