Open AccessNew Recombinant Escherichia coli Strain Tailored for the Production of Poly(3-Hydroxybutyrate) from Agroindustrial By-Products
Author(s) -
Pablo I. Nikel,
Alejandra de Almeida,
Evelia C. Melillo,
Miguel A. Galvagno,
M. Julia Pettinari
Publication year - 2006
Publication title -
applied and environmental microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.552
H-Index - 324
eISSN - 1070-6291
pISSN - 0099-2240
DOI - 10.1128/aem.00044-06
Subject(s) - cupriavidus necator , strain (injury) , lactose , lac repressor , escherichia coli , bioplastic , food science , corn steep liquor , azotobacter , bioreactor , bacteria , chemistry , recombinant dna , biochemistry , fermentation , microbiology and biotechnology , biology , polyhydroxyalkanoates , lac operon , gene , organic chemistry , ecology , genetics , anatomy
A recombinantE. coli strain (K24K) was constructed and evaluated for poly(3-hydroxybutyrate) (PHB) production from whey and corn steep liquor as main carbon and nitrogen sources. This strain bears thepha biosynthetic genes fromAzotobacter sp. strain FA8 expressed from a T5 promoter under the control of the lactose operator. K24K does not produce the lactose repressor, ensuring constitutive expression of genes involved in lactose transport and utilization. PHB was efficiently produced by the recombinant strain grown aerobically in fed-batch cultures in a laboratory scale bioreactor on a semisynthetic medium supplemented with the agroindustrial by-products. After 24 h, cells accumulated PHB to 72.9% of their cell dry weight, reaching a volumetric productivity of 2.13 g PHB per liter per hour. Physical analysis of PHB recovered from the recombinants showed that its molecular weight was similar to that of PHB produced byAzotobacter sp. strain FA8 and higher than that of the polymer fromCupriavidus necator and that its glass transition temperature was approximately 20°C higher than those of PHBs from the natural producer strains.