Hydrolysis of potato processing waste for the production of poly-beta-hydroxybutyrate

The enzymatic hydrolysis of potato processing wastes has been studied as a possible source of a fermentable substrate for the production of the biopolymer poly-beta-hydroxybutyrate (PHB) from the bacterium Alcaligenes eutrophus. PHB has been proposed as a biodegradable substitute for conventional thermoplastics. The results indicated that potato starch waste could be converted with high yield to a concentrated glucose solution. The most economical process used barley malt as a source of amylase enzyme with an optimal ratio of 10:90 g/g of potato waste. A conversion efficiency of 96% of theoretical was obtained with a final glucose concentration of 208 mg/ml. After dilution and addition of mineral salts the hydrolysate was converted by a batch culture of A. eutrophus to 5.0 g/l of PHB, comprising 77% of the biomass dry weight.