Influence of unusual co-substrates on the biosynthesis of medium-chain-length polyhydroxyalkanoates produced in multistage chemostat

Hanik, Nils (School of Engineering, HES-SO Valais-Wallis, HEI, HES-SO // University of Applied Sciences Western Switzerland) ; Utsunomia, Camila (School of Engineering, HES-SO Valais-Wallis, HEI, HES-SO // University of Applied Sciences Western Switzerland) ; Zinn, Manfred (School of Engineering, HES-SO Valais-Wallis, HEI, HES-SO // University of Applied Sciences Western Switzerland) ; Arai, Shuzo (Graduate School of Chemical Sciences and engineering, Hokkaido University, Sapporo, Japan) ; Matsumoto, Ken'ichiro (Division of Applied Chemistry, Faculty of Engineering, Hokkaido University, Sapporo, Japa)

A two-stage chemostat cultivation was used to investigate the biosynthesis of functionalized medium-chain-length polyhydroxyalkanoate (mcl-PHA) in the β-oxidation weakened strain of Pseudomonas putida KTQQ20. Chemostats were linked in sequence and allowed separation of biomass production in the first stage from the PHA synthesis in the second stage. Four parallel reactors in the second stage provided identical growth conditions and ensured that the only variable was the ratio of decanoic acid (C10) to an unusual PHA monomer precursor, such as 10-undecenoic acid (C11:1) or phenylvaleric acid (PhVA). Obtained PHA content was in the range of 10 to 25 wt%. When different ratios of C10 and C11:1 were fed to P. putida, the produced PHA had a slightly higher molar ratio in favor of C11:1-based 3-hydroxy-10-undecenoate. However, in case of PhVA a significantly lower incorporation of 3-hydroxy-5-phenylvalerate over 3-hydroxydecanoate took place when compared to the ratio of their precursors in the feed medium. A result that is explained by a less efficient uptake of PhVA compared to C10 and a 24% lower yield of polymer from the aromatic fatty acid (yPHA−MPhVA = 0.25). In addition, PHA isolated from cultivations with PhVA resulted in the number average molecular weight Mn two times lower than the PHA produced from C10 alone. Detection of products from PhVA metabolism in the culture supernatant showed that uptaken PhVA was not entirely converted into PHA, thus explaining the difference in the yield polymer from substrate. It was concluded that PhVA or its related metabolites increased the chain transfer rate during PHA biosynthesis in P. putida KTQQ20, resulting in a reduction of the polymer molecular weight.


Keywords:
Article Type:
scientifique
Faculty:
Ingénierie et Architecture
School:
HEI-VS
Institute:
Institut Technologies du vivant
Date:
2019-11
Pagination:
9 p.
Published in:
Frontiers in Bioengineering and Biotechnology
Numeration (vol. no.):
2019, vol. 7, article no. 301
DOI:
ISSN:
2296-4185
Appears in Collection:



 Record created 2020-01-24, last modified 2020-01-24

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