Production of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) by Ralstonia eutropha in high cell density palm oil fermentations

• Published in: Biotechnology and bioengineering Vol. 109; no. 1; pp. 74 - 83
• Main Authors: Riedel, Sebastian L., Bader, Johannes, Brigham, Christopher J., Budde, Charles F., Yusof, Zainal Abidin Mohd, Rha, ChoKyun, Sinskey, Anthony J.
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc., A Wiley Company 01-01-2012; Wiley Subscription Services, Inc
• Subjects: 3-Hydroxybutyric Acid - metabolism; Biomass; Bioreactors - microbiology; Caproates - metabolism; Culture; Culture Media - chemistry; Cupriavidus necator - growth & development; Cupriavidus necator - metabolism; Density; Fermentation; Gram-negative bacteria; high cell density fermentation; Nitrogen - metabolism; Oils & fats; Palm Oil; plant oil; Plant Oils - metabolism; Poly(hydroxybutyrate-co-hydroxyhexanoate); Polyhydroxyalkanoate; Polymers; Ralstonia eutropha; Recombinant; Strain; Strategy
• ISSN: 0006-3592; 1097-0290; 1097-0290
• DOI: 10.1002/bit.23283

Improved production costs will accelerate commercialization of polyhydroxyalkanoate (PHA) polymer and PHA‐based products. Plant oils are considered favorable feedstocks, due to their high carbon content and relatively low price compared to sugars and other refined carbon feedstocks. Different PHA production strategies were compared using a recombinant strain of Ralstonia eutropha that produces high amounts of P(HB‐co‐HHx) when grown on plant oils. This R. eutropha strain was grown to high cell densities using batch, extended batch, and fed batch fermentation strategies, in which PHA accumulation was triggered by nitrogen limitation. While extended batch culture produced more biomass and PHA than batch culture, fed batch cultivation was shown to produce the highest levels of biomass and PHA. The highest titer achieved was over 139 g/L cell dry weight (CDW) of biomass with 74% of CDW as PHA containing 19mol% HHx. Our data suggest that the fermentation process is scalable with a space time yield (STY) better than 1 g PHA/L/h. The achieved biomass concentration and PHA yield are among the highest reported for the fermentation of recombinant R. eutropha strains producing P(HB‐co‐HHx). Biotechnol. Bioeng. 2012;109: 74–83. © 2011 Wiley Periodicals, Inc.