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Polyhydroxyalkanoates production with Ralstonia eutropha from low quality waste animal fats

: Riedel, S.L.; Jahns, S.; Koenig, S.; Bock, M.C.E.; Brigham, C.J.; Bader, J.; Stahl, U.


Journal of biotechnology 214 (2015), S.119-127
ISSN: 0168-1656
ISSN: 1389-0352
ISSN: 1873-4863
Fraunhofer IPK ()

Polyhydroxyalkanoates (PHAs) are biodegradable and biocompatible polyesters considered as alternatives to petroleum-based plastics. Ralstonia eutropha is a model organism for PHA production. Utilizing industrially rendered waste animal fats as inexpensive carbon feedstocks for PHA production is demonstrated here. An emulsification strategy, without any mechanical or chemical pre-treatment, was developed to increase the bioavailability of solid, poorly-consumable fats. Wild type R. eutropha strain H16 produced 79–82% (w/w) polyhydroxybutyrate (PHB) per cell dry weight (CDW) when cultivated on various fats. A productivity of 0.3 g PHB/(L × h) with a total PHB production of 24 g/L was achieved using tallow as carbon source. Using a recombinant strain of R. eutropha that produces poly(hydroxybutyrate-co-hydroxyhexanoate) [P(HB-co-HHx)], 49–72% (w/w) of PHA per CDW with a HHx content of 16–27 mol% were produced in shaking flask experiments. The recombinant strain was grown on waste animal fat of the lowest quality available at lab fermenter scale, resulting in 45 g/L CDW with 60% (w/w) PHA per CDW and a productivity of 0.4 g PHA/(L × h). The final HHx content of the polymer was 19 mol%. The use of low quality waste animal fats as an inexpensive carbon feedstock exhibits a high potential to accelerate the commercialization of PHAs.