The production of poly(3-hydroxybutyrate) by thermophilic Caldimonas manganoxidans from glycerol

Glycerol is an abundant and inexpensive raw material, suitable for the use in fermentation as value adding to agricultural waste. To fully understand how to convert both pure and refined glycerol into Poly(3-hydroxybutyrate) (PHB) using thermophilic Caldimonas manganoxidans. A high PHB concentration can be obtained by using the following fermentation conditions: unbuffered initial pH of 7 and 50 degrees C. The preset fermentation conditions with initial glycerol concentration of 50 g/Lyielded a PHB concentration of 8.4 +/- 1.5 g/L, PHB content of 71 +/- 7 wt%, and an average molecular weight of 123 kDa. The average molecular weight of PHB as produced can be controlled by the initial glycerol concentration whereas a trade-off between the initial glycerol concentration and the average molecular weight was reported. The feasibility of using refined glycerol as carbon source for PHB production has been demonstrated. It is tunable to produce different Mw of PHB using glycerol, while biodiesel-derived glycerol can be used as carbon source.