Effect of Various Carboxylic Acids on the Biosynthesis of Polyhydroxyalkanoate in Pseudomonas aeruginosa PA01

      In the present study, four carbon sources were tested for the polyester synthesis of Pseudomonas aeruginosa PA01 which is a ubiquitous environmental bacterium and is one of the top three causes of opportunistic human infections. These included linear C8 to C11 carboxylic acids. Octanoic acid, nonanoic acid, decanoic acid and undecanoic acid were added to M1 minimal medium to final concentrations of 60, 40, 30 and 20 mM, respectively. When P. aeruginosa was cultivated in M1 minimal medium with decanoate and nonanoate as the sole carbon sources, polyhydroxyalka-noate (PHA) was achieved up to 55.75% (w/w) and 24.53% (w/w), respectively. The maximum PHA yield at 30 ºC was obtained when decanoic acid was used as sole carbon source. Use of nonanoic acid as carbon source was resulted in a minimum PHA yield at 30 ºC. An increase in the cultivation temperature from 30 ºC to 37 ºC resulted in decrease of PHA content and cell dried weight as well. Based on the type of carbon source different monomers at the level higher than 1 mol% to 62 mol% were detected which included 3-hydroxyoheptanoic acid (C7), 3-hydroxyoctanoic acid (C8), 3-hydroxynonanoic acid (C9), 3-hydroxydecanoic acid (C10), and 3-hydroxyundecanoic acid (C11).