Optimum growth conditions and pH control solution for PHB biosynthesis in A. eutrophus

Optimum growth conditions and pH control solution were obtained in the biosynthesis of PHB(poly-β-hydroxybutyrate) with Alcaligenes eutrophus. Optimum carbon and nitrogen sources were fructose and (NH₄) ₂SO₄, respectively, and optimum additive was 1:1 mixture of yeast extract and polypeptone. To select the optimum pH control solution, various pH control solutions (NaOH, KOH, Na₂CO₃, and NaOH+KOH) were tested. Na₂CO₃ solution was found to be the best out of the four solutions tested, because CO₂ generated from Na₂CO₃ could be used as a carbon source. Mixture of NaOH and KOH showed better results than the solution of NaOH or KOH alone. This could be due to the balanced amount of cations (Na⁺ and K⁺), which might promote not only the permeation of substrates, but also pumping out Na⁺ ions.