Recombinant Escherichia coli strains with inducible Campylobacter jejuni single domain hemoglobin CHb expression exhibited improved cell growth in bioreactor culture

PLoS One. 2015 Mar 6;10(3):e0116503. doi: 10.1371/journal.pone.0116503. eCollection 2015.

Abstract

Maintaining an appropriate concentration of dissolved oxygen in aqueous solution is critical for efficient operation of a bioreactor, requiring sophisticated engineering design and a system of regulation to maximize oxygen transfer from the injected air bubbles to the cells. Bacterial hemoglobins are oxygen-binding proteins that transfer oxygen from the environment to metabolic processes and allow bacteria to grow even under microaerophilic conditions. To improve the oxygen utilization efficiency of cells and overcome the oxygen shortage in bioreactors, the gene coding for the Campylobacter jejuni single domain hemoglobin (CHb) gene was artificially synthesized and functionally expressed under the control of inducible expression promoters PT7 and Pvgh in Escherichia coli. The effects of the recombinants PT7-CHb and Pvgh-CHb on cell growth were evaluated in aerobic shake flasks, anaerobic capped bottles and a 5-L bioreactor, and a pronounced improvement in cell biomass was observed for CHb-expressing cells. To determine the growth curves, CHb gene expression, and CHb oxygen-binding capacity of specific recombinants with different promoters, we determined the time course of CHb gene expression in the two recombinants by semi-quantitative RT-PCR and CO differential spectrum assays. Based on the growth patterns of the two recombinants in the bioreactor, we proposed different recombinant types with optimal performance under specific culture conditions.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bioreactors*
  • Campylobacter jejuni / genetics*
  • Campylobacter jejuni / growth & development
  • Campylobacter jejuni / metabolism
  • Escherichia coli / genetics*
  • Escherichia coli / growth & development
  • Genes, Bacterial
  • Hemoglobins / genetics
  • Hemoglobins / metabolism*
  • Recombination, Genetic*
  • Reverse Transcriptase Polymerase Chain Reaction

Substances

  • Hemoglobins

Grants and funding

Science and Technology Supporting Program of Hubei Province (2014), Key Project of Science and Technology Research Program of the Education Department of Hubei Province (no. D20131703), the Key Project of Chinese Ministry of Education (no. 212118).