Effects of culture conditions on the production of polyhydroxyalkanoates by Azotobacter chroococcum H23 in media containing a high concentration of alpechı́n (wastewater from olive oil mills) as primary carbon source

Abstract

Large amounts of homopolymers containing β-hydroxybutyrate (PHB) and copolymers containing β-hydroxyvalerate (P[HB-co-HV]) are produced by Azotobacter chroococcum strain H23 when growing in culture media amended with alpechı́n (wastewater from olive oil mills) as the sole carbon source. Copolymer was formed when valerate (pentanoate) was added as a precursor to the alpechı́n medium, but it was not formed with the addition of propionate as a precursor. A. chroococcum formed homo- and copolymers of polyhydroxyalkanoates (PHAs) up to 80% of the cell dry weight, when grown on NH 4 +-medium supplemented with 60% (v/v) alpechı́n, after 48 h of incubation at 100 rev min −1 and 30 °C. Production of PHAs by strain H23 using alpechı́n looks promising, as the use of a cheap substrate for the production of these materials is essential if bioplastics are to become competitive products.