Thermophilic enrichment of microbial communities in the presence of tetrabutylphosphonium chloride and tributylethylphosphonium diethylphosphate ionic liquids

Ionic liquids have been used as a pretreatment technique for efficient lignin removal from renewable lignocellulosic feedstock to expedite processing time for biomass based biofuels.  The aim for this study was to identify thermophilic microbial communities tolerant to tetrabutylphosphonium chloride (tetra butyl) and tributylethylphosphonium diethylphosphate (diethyl) ionic liquids (ILs) that can efficiently decompose lignocellulose in a high-solids environment.  High-solids incubations were conducted with green waste as a feedstock and using compost as an initial inoculum to enrich for communities capable of growing in the presence of tetra butyl and diethyl ionic liquids.  Respiration rates were measured to determine community tolerance to a maximum IL concentration up to 75 mM.  Enriched communities were sequenced to determine the impact of IL concentration on the diversity of the communities and to identify microorganisms capable of tolerating high levels of IL for potential industrial relevance. 16S rRNA gene sequencing revealed a shift in community structure when subjected to thermophilic conditions and increased IL concentration.  Enriched communities were stored using cryogenic preservation and plating techniques and revived to test the viability of stored communities and continual tolerance to ILs.