Microbial production of poly(hydroxyalkanoate)s from waste edible oils

Abstract

The biosynthesis of poly(3-hydroxyalkanoate) (PHA) from waste edible oils and tallow by Ralstonia eutropha was investigated. Waste plant oils as well as waste tallow were assimilated and successfully converted to PHA with relatively high yield by the bacterial fermentation. The waste plant oils usually gave poly(3-hydroxybutyrate) (PHB) while waste tallow gave poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV). The ratio of 3-hydroxyvalerate (3HV) unit in the copolyester was controlled by the addition of sodium propionate to the cultivation medium containing waste plant oils as carbon sources. The ratio of PHA accumulated was also quite high and up to 80% of the cell dry weight. The PHA accumulated was easily isolated by simply mixing the cells in aqueous sodium hypochlorite without using any organic solvents. We propose herein the biorecycling of waste oils as renewable resources for sustainable society.