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Development of a closed‐loop control system for production of medium‐chain‐length poly(3‐hydroxyalkanoates) (mcl‐PHAs) from bacteria
Author(s) -
Kellerhals Michele B.,
Kessler Birgit,
Witholt Bernard
Publication year - 1999
Publication title -
macromolecular symposia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.257
H-Index - 76
eISSN - 1521-3900
pISSN - 1022-1360
DOI - 10.1002/masy.19991440136
Subject(s) - bacteria , chain (unit) , loop (graph theory) , production (economics) , control (management) , closed loop , chemistry , computer science , biology , control engineering , engineering , mathematics , physics , genetics , combinatorics , economics , macroeconomics , astronomy , artificial intelligence
Large scale availability of bacterial polyhydroxyalkanoates (PHAs) is still limited to a few types of short‐chain‐length PHAs, namely poly(3‐hydroxybutyrate) (PHB) and its copolymer Biopol™, consisting of 3‐hydroxybutyrate and 3‐hydroxyvalerate repeating units. In order to increase the number of available medium‐chain‐length PHA (mcl‐PHA) copolymers a flexible high‐cell‐density fed‐batch process was developed. Continuous process monitoring and substrate control were achieved by coupling on‐line gaschromatography (on‐line GC) to a software‐based Proportional Integral (PI) substrate controller. System development time and continuous system upgrading were considerably shortened by using LABV iew™, a powerful graphical programming environment. The control of octanoic acid and 10‐undecenoic acid at 1.5 and 0.5 gL −1 respectively, enabled the production of high levels of biomass (30 gL −1 ) and mcl‐PHA (10.5 gL −1 ) by avoiding substrate limitations or toxicities. The resulting mcl‐PHA was an amorphous copolyester consisting of 37 mol% unsaturated monomers. The present system represents a valuable tool for the production of tailor‐made mcl‐PHAs, where the desired monomer composition is determined by the ratio of added cosubstrates.