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Mass Spectrometry Feedback Control for Synthesis of Polyhydroxyalkanoate Granule Microstructures in Ralstonia eutropha
Author(s) -
Pederson Erik N.,
Srienc Friedrich
Publication year - 2004
Publication title -
macromolecular bioscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.924
H-Index - 105
eISSN - 1616-5195
pISSN - 1616-5187
DOI - 10.1002/mabi.200300137
Subject(s) - ralstonia , polyhydroxyalkanoates , granule (geology) , cupriavidus necator , chemistry , mass spectrometry , biochemistry , chromatography , materials science , biology , bacteria , enzyme , genetics , composite material
Summary: Polyhydroxyalkanoate (PHA) granules with core‐shell layered microstructure were synthesized in Ralstonia eutropha using periodic feeding of valeric acid into a growth medium containing excess fructose. The O 2 consumption and CO 2 evolution rates, determined by off‐gas mass spectrometry, have been used as sensitive measures to indicate the type of nutrients utilized by R. eutropha during PHA synthesis. Domains of poly‐3‐hydroxybutyrate (PHB) were formed during polymer storage conditions when only fructose was present. Feeding of valeric acid (pentanoic acid) resulted in the synthesis of hydroxyvalerate (HV) monomers, forming a poly‐3‐hydroxybutyrate‐ co ‐valerate (PHBV) copolymer. The synthesis of desired polymer microstructures was monitored and controlled using online mass spectrometry (MS). The respiratory quotient (RQ) was unique to the type of polymer being synthesized due to increased O 2 consumption during PHBV synthesis. MS data was used as the control signal for nutrient feeding strategies in the bioreactor. The core‐shell structures synthesized were verified in cells using transmission electron microscopy after thin sectioning and staining with RuO 4 . It was demonstrated that the synthesis of core‐shell microstructures can be precisely controlled utilizing a MS feedback control system.Monitoring of R. eutropha growth and PHA synthesis in a batch reactor (oxygen uptake rate: OUR; carbon dioxide evolution rate: CER; respiratory quotient: RQ).