High cell density culture of metabolically engineered Escherichia coli for the production of poly(3‐hydroxybutyrate) in a defined medium

Abstract

A recombinant Escherichia coli strain XL1-Blue harboring a stable high-copy-number plasmid pSYL107 containing the Alcaligenes eutrophus polyhydroxyalkanoate biosynthesis genes and the Escherichia coli ftsZ gene was employed for the production of poly(3-hydroxybutyrate) (PHB) by fed-batch culture in a defined medium. Suppression of filamentation by overexpressing the cell division protein FtsZ allowed production of PHB to a high concentration (77 g/L) with high productivity (2 g/L/h) in a defined medium, which was not possible with the recombinant E. coli that underwent filamentation. Further optimization of fed-batch culture condition resulted in PHB concentration of 104 g/L in a defined medium, which was the highest value reported to date by employing recombinant E. coli.

Mutations Derived from the Thermophilic Polyhydroxyalkanoate Synthase PhaC Enhance the Thermostability and Activity of PhaC from Cupriavidus necator H16

“…3A). At a temperature of 30°C, highcell-density fermentation for the mass production of PHB was reported (49,50). At this temperature, chimeric PhaC H16␤ has a higher specific activity than those of its parental enzymes PhaC Csp and PhaC H16 .…”

“…This study employed E. coli XL1-Blue, a strain commonly used for PHA fermentation (4,49,50), as the host cell line for the PHA accumulation experiment. Fotadar et al and Hoffman et al reported previously that E. coli DH5␣ is capable of growth at temperatures of up to 49°C, although growth is prohibitive beyond 40°C (8,15).…”

“…PHAs have been intensively studied since Lemoigne discovered poly(␤-hydroxybutyrate) (PHB) in the bacterium Bacillus megaterium in 1926 (2,19,21,22). Bacterial fermentation is a method commonly used for the mass production of PHA (49,50). Numerous bacteria, such as Cupriavidus necator H16 (formerly Ralstonia eutropha H16) (46), Alcaligenes latus, Methylobacterium organophilum, and recombinant Escherichia coli, have been studied for the production of PHA to a high concentration with a high level of productivity (6).…”

PHB Production in Biofermentors Assisted through Biosensor Applications

“…Today, costs of production of PHAs is high, around US$ 4-6/ kg, including also costs for polymer extraction and recovery [28,50]. PHB granules being cytosolic, mechanical or chemical methods are required for cell disruption.…”

“…Recombinant E. coli producing PHB grow rapidly, accumulate PHB for about 50% of dry weight [28][29][30][31][32], and are able to exploit various carbohydrates [33,34]. Several factors (i.e., type of feed, aeration conditions) influence the biomass growth rate and PHB production and molecular weight size.…”