Raposo, Rodrigo S.Almeida, M. Catarina M. D. deFonseca, M. M. R. daCesário, M. Teresa2019-12-092019-12-092017-12Int J Biol Macromol. 2017 Dec;105(Pt 1):825-833. doi: 10.1016/j.ijbiomac.2017.07.1110141-8130http://hdl.handle.net/10400.26/30414Poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P(3HB-4HB)) co-polymers were produced at bench-scale in fed-batch cultivations by Burkholderia sacchari from glucose (main carbon-source) and gamma-butyrolactone (GBL) as co-substrate. As P(3HB-4HB) properties highly depend on the 4-hydroxybutyrate (4HB) molar fraction, it is advantageous to have a thorough knowledge of the process in order to promote the production of the targeted final product. In this work, polymers with a 4HB molar percentage ranging from 1.5 to 8.4% (mol/mol) were obtained as consequence of a fine tuning of the fed-batch operation conditions, namely regarding the co-substrate feeding rate and its addition time, as GBL is toxic to B. sacchari cells. The best results regarding both the 4HB incorporation (molar%) and the co-polymer productivity (7.1% and 1.1g/(L.h) respectively) were reached when a pulse of GBL (<10g/L) was added early in the accumulation phase followed by a constant GBL addition at a rate similar to that of consumption so that a steady co-substrate concentration in the medium was maintained.engBurkholderia sacchariPoly (3-hydroxybutyrate-co-4-hydroxybutyrate)P(3HB-4HB)Gamma-butyrolactoneBioreactor feeding strategyjournal article10.1016/j.ijbiomac.2017.07.111