Starch based polyhydroxybutyrate production in engineered Escherichia coli

Abstract

Every year, the amount of chemosynthetic plastic accumulating in the environment is increasing, and significant time is required for decomposition. Bio-based, biodegradable plastic is a promising alternative, but its production is not yet a cost effective process. Decreasing the production cost of polyhydroxyalkanoate by utilizing renewable carbon sources for biosynthesis is an important aspect of commercializing this biodegradable polymer. An <em>Escherichia coli</em> strain that expresses a functional amylase and accumulate polyhydroxybutyrate (PHB), was constructed using different plasmids containing the amylase gene of <em>Panibacillus</em> sp. and PHB synthesis genes from<em> Ralstonia eutropha.</em> This engineered strain can utilize starch as the sole carbon source. The maximum PHB production (1.24 g/L) was obtained with 2 % (w/v) starch in M9 media containing 0.15 % (w/v) yeast extract and 10 mM glycine betaine. The engineered<em> E. coli </em>SKB99 strain can accumulate intracellular PHB up to 57.4 % of cell dry mass.