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Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) production from engineered Ralstonia eutropha using synthetic and anaerobically digested food waste derived volatile fatty acids

Bhatia, Shashi Kant, Gurav, Ranjit, Choi, Tae-Rim, Jung, Hye-Rim, Yang, Soo-Yeon, Song, Hun-Suk, Jeon, Jong-Min, Kim, Jae-Seok, Lee, Yoo-Kyung, Yang, Yung-Hun
International journal of biological macromolecules 2019 v.133 pp. 1-10
Cupriavidus necator, acetates, butyrates, composite polymers, food waste, lactic acid, nitrogen, polyhydroxyalkanoates, volatile fatty acids
Ralstonia eutropha Re2133/pCB81 is able to utilize various volatile fatty acids (VFAs) (acetate, butyrate, lactate, and propionate) for polyhydroxyalkanoates (PHAs) production. Acetate and lactate resulted in poly(3-hydroxybutyrate) P(3HB) production, butyrate in poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) P(3HB-co-3HHx), and propionate in poly(3-hydroxybutyrate-co-3-hydroxyvalerate) P(3-HB-co-3HV). Various biomass yields i.e. (Yx/s, 0.131 ± 0.02 g/g acetate, 0.221 ± 0.02 g/g butyrate, 0.222 ± 0.05 g/g lactate, and 0.225 ± 0.04 g/g propionate) and PHA yields (Yp/s, 0.01 ± 0.001 g/g acetate, 0.11 ± 0.004 g/g butyrate, 0.03 ± 0.001 g/g lactate, and 0.18 ± 0.005 g/g propionate) were observed with the different organic acids. When all the organic acids were mixed together R. eutropha Re2133/pCB81 had the following order of preference; lactate > butyrate > propionate > acetate. A response surface design study showed that in mixtures butyrate is the main organic acid involved in PHA production and acts as a precursor for HHx monomer units to produce copolymer P(3HB-co-3HHx). Food waste ferment (FWF) without any additional nitrogen source and precursors resulted in P(3HB-co-3HHx) accumulation (52 ± 4% w/w with 18.5 ± 3% HHx fraction).