Escherichia coli Fermentation Services

BOC Sciences developed a platform that addresses the advancement of various microbial strains and multiple cell lines. Among these microbial strains, Escherichia coli is the most widely studied and applicable prokaryotic organism, as well as a critical host organism in biotechnology and microbiology. Due to our extensive experience in microbial fermentation, we are capable of utilizing Escherichia coli as a host strain to improve metabolic processes for target compounds production and protein of interest expression. Our Escherichia coli system is an efficient biotechnological tool in a wide range of microbial fermentation projects and provides cost-effective and high-quality solutions to our customers.

Introduction of E. coli

Escherichia coli, abbreviated as E. coli, was first discovered in 1885 as a Gram-negative, facultative anaerobic, rod-shaped, coliform bacterium of the genus Escherichia. The first complete DNA sequence of E. coli genome was published in 1997. This circular DNA molecule has 4.6 million base pairs in length, 4288 annotated protein-coding genes (organized into 2584 operons), seven rRNA operons, and 86 tRNA genes. In addition, the coding density was found to be high, with a mean distance of 118 base pairs between genes.

E. coli can survive on multiple substrates and ferment under anaerobic conditions using mixed acids to produce lactic acid, succinic acid, acetic acid, ethanol and carbon dioxide. Since many pathways in mixed acid fermentation produce hydrogen, these pathways require low hydrogen levels. The optimal growth of E. coli occurs at 37 ℃, but certain laboratory strains can multiply at temperatures upward to 49 ℃.

Advantages of E. coli Fermentation

Genetic engineering technology is an important tool for the rapid development and production of essential biologicals within biotechnology. This type of technology creates more cost-effective methods related to the production process and the marketability of products. Among them, E. coli was most widely used in fermentation production for various primary, secondary metabolites and proteins.

• Due to its simplicity, relatively low cost, and rapid growth, E. coli is a favored expression platform for producing recombinant proteins of interest in controlled laboratory and industrial settings.
• Since E. coli does not naturally export many proteins into the periplasm, the recovery of the protein of interest will occur with minimal contamination of unwanted host cytosolic proteins, DNA, or endotoxins.
• In general, E. coli is a chemoheterotroph whose medium requires a source of carbon as energy. However, E. coli can be constructed and evolved in order to produce all its biomass carbon through CO₂ as the sole carbon source. This heterotroph's metabolism can be altered by heterologous expression within carbon fixation genes to display autotrophic capabilities.

Experience of E. coli Fermentation

BOC Sciences has extensive experience in the strains and fermentation process for protein expression and metabolic engineering in E. coli. We are able to achieve a high-level expression of many proteins in the active form through medium and fermentation process optimization.

• Appropriate control of the rate of fed and specific growth rate, and management of acetic acid amount, a metabolic by-product of the E. coli fermentation process.
• Ensure sufficient dissolved oxygen and strict pH control, including maintaining the rate of acid-base supplementation for as moderate as possible.
• Temperature control of protein expression. Most of the proteins produced at lower fermentation temperatures are active, while proteins produced at higher temperatures are usually in the form of inclusion bodies.
• Maintenance of a reasonable induction time, and generally the induction time is chosen at the late stage of exponential growth.
• Control of carbon-nitrogen ratio in fed-batch fermentation. If the nitrogen source is too high, resulting in high pH, this is not conducive to the accumulation of metabolites. Still, when the nitrogen source is not enough, this leads to less reproduction of the bacterium, thus affecting the yield.

Our Methods for E. coli Fermentation

The process of producing vital biologics using recombinant DNA technology consists of six main aspects:

• Selection of a suitable host.
• Identification of recombinant protein accumulation sites
• Strategy for maximum expression of recombinant genes.
• Optimization of the culture medium and cell growth environment.
• Control of fermentation conditions.
• Development of protein separation and recovery processes.

Project workflow of E. coli Fermentation

• Customer advisory
• Project discussion
• E. coli served as host cell
• Strain improvement and fermentation development
• Novel strain evaluation
• Project delivery

References

1. Isabel G. M., et al. Comparative proteome analysis in an Escherichia coli CyDisCo strain identifies stress responses related to protein production, oxidative stress and accumulation of misfolded protein, Microb Cell Fact, 2019, 18-19.
2. Shmuel G., et al. Conversion of Escherichia coli to Generate All Biomass Carbon from CO₂, Cell, 2019, 179(6): 1255-1263.
3. F R Blattner, et al. The complete genome sequence of Escherichia coli K-12, Science, 1997, 277(5331):1453-62.