Optimization of Polyhydroxyalkanoate Production by Recombinant E. coli Supplemented with Different Plant By-ProductsAuthor(s): Mezzolla V, DUrso OF and Poltronieri P
Polyhydroxyalkanoates (PHAs) are biodegradable polymers synthesized in cytoplasmic granules in bacteria, such as Cupriavidus necator (Ralstonia eutropha), and several other bacteria. PHAs accumulation occurs in response to stress conditions, i.e. under high carbon and low nitrogen (24:1 ratio). In this study, E. coli was genetically modified for PHA production in biofermentors. PHA was synthesized in bacteria transformed with the operon phbA/phbB/phbC. The bacteria were fed using a basal medium supplemented with three different plant by-products, potato tuber skin hydrolysate, corn hydrolysate, and banana juice supplement. The growth in biofermentor was monitored through the evaluation of consumption of sugars and quantification of PHA synthesis. A microarray scanner was used to read fluorescence intensity of Nile Blue stained bacteria. PHA production by E. coli fed on a banana juice supplement outperformed all the other fermentation media, with highest amount of PHA per dry cell weight.