Production of nitrogen-based platform chemical: cyanophycin biosynthesis using recombinantEscherichia coliand renewable media substitutes

Abstract

Background Cyanophycin (CGP) is a sustainable polymer that can be converted to a derivative with reduced arginine content, or to completely biodegradable poly-aspartic acid, which can substitute for non-biodegradable polyacrylates. In nature, it is produced by most cyanobacteria; however, these microbes are not suitable for large-scale production due to slow growth and low polymer content. Results Cyanophycin synthetase gene (cphA) from Anabaena variabilis ATCC 29413 was PCR amplified and cloned into Escherichia coli. Different renewable media components, such as soybean meal, potato wastes and corn-derived zein hydrolysate, were evaluated for their feasibility for CGP production at shake flask level. The optimized conditions were then tested in a 7 L bioreactor; a maximum cell weight of 10.2 g L-1 was obtained. CGP comprised 23 g g-1 of cell dry matter (CDM) with molecular weight between 21.5 and 31 kDa and was composed of aspartic acid, arginine and lysine in the ratio of 1.05:1:0.2 (mass basis). Conclusion The efficient use of renewable biomass for cyanophycin production could achieve competitive price, and in return, promote the use of this platform chemical to produce innovative polymers and materials.© 2012 Society of Chemical Industry