Effect of anaerobic promoters on the microaerobic production of polyhydroxybutyrate (PHB) in recombinant <Emphasis Type="Italic">Escherichia coli</Emphasis> |
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Authors: | Xiao-Xing Wei Zhen-Yu Shi Mei-Qing Yuan Guo-Qiang Chen |
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Institution: | (1) MOE Laboratory for Protein Sciences, Department of Biological Sciences and Biotechnology, Tsinghua University, Beijing, 100084, China;(2) College of Biology Science, China Agricultural University, Beijing, 100094, China;(3) Multidisciplinary Research Center, Shantou University, Guangdong, 515063, China |
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Abstract: | Nine anaerobic promoters were cloned and constructed upstream of PHB synthesis genes phbCAB from Ralstonia eutropha for the micro- or anaerobic PHB production in recombinant Escherichia coli. Among the promoters, the one for alcohol dehydrogenase (P
adhE
) was found most effective. Recombinant E. coli JM 109 (pWCY09) harboring P
adhE
and phbCAB achieved a 48% PHB accumulation in the cell dry weight after 48 h of static culture compared with only 30% PHB production
under its native promoter. Sixty-seven percent PHB was produced in the dry weight (CDW) of an acetate pathway deleted (Δpta deletion) E. coli JW2294 harboring the vector pWCY09. In a batch process conducted in a 5.5-l NBS fermentor containing 3 l glucose LB medium,
E. coli JW2294 (pWCY09) grew to 7.8 g/l CDW containing 64% PHB after 24 h of microaerobic incubation. In addition, molecular weight
of PHB was observed to be much higher under microaerobic culture conditions. The high activity of P
adhE
appeared to be the reason for improved micro- or anaerobic cell growth and PHB production while high molecular weight contributed
to the static culture condition. |
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Keywords: | PHB Polyhydroxyalkanoates Microaerobiosis Anaerobic promoter phbCAB Alcohol dehydrogenase |
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