1-Ethyl-3-methylimidazolium Diethylphosphate Based Extraction of Bioplastic “Polyhydroxyalkanoates” from Bacteria: Green and Sustainable Approach

Abstract

An eco-friendly approach toward downstream processing of bacterial biomass for extraction of an intracellular potential bioplastic material polyhydroxyalkanoates replacing chlorinated organic solvents is reported using ionic liquid (IL) 1-ethyl-3-methylimidazolium diethylphosphate ([C2mim][(C2)2OPO3]) as an extractant. [C2mim][(C2)2OPO3] dissolved wet bacterial biomass of Halomonas hydrothermalis (MTCC accession no. 5445; NCBI Genbank accession no. GU938192), with ease on account of its high hydrogen bond basicity (β = 1.07). The recovered polymer with a yield of 60% ± 2% was characterized using 1H NMR, FT-IR, and TGA techniques and confirmed to be polyhydroxybutyrate (PHB). The properties of PHB were found to be in close proximity to the standard PHB. The [C2mim][(C2)2OPO3] was recovered with 60% yield and retention of chemical structure after two consecutive dissolution cycles, which minimized the cost of developed process. The recovered PHB was used to prepare a bioplastic film, which showed good thermal and mechanical stability, as characterized by FT-IR, DSC, TGA, and DMA techniques.