Comparative Analysis of Yeast and E. coli in Release Testing

In the field of biopharmaceuticals, Escherichia coli (E. coli) and yeast are two widely used microbial expression systems that have addressed significant challenges such as industrialization and batch-to-batch stability of biological products. Leveraging their advantages of clear genetic backgrounds and mature technology, they have been utilized in the production of various preventive or therapeutic biological products, including the 9-valent HPV vaccine, GLP-1, insulin and insulin analogs, interleukin-2, interferon, plasmid DNA in Yaohai Bio-Pharma.

Driven by the need for multi-batch and continuous production, implementing a strain bank management system and establishing reasonable release testing can ensure the uniformity and stability of production strains, thereby guaranteeing consistency and quality of biological products. As E. coli and yeast belong to bacteria and fungi respectively, their molecular construction strategies for engineered strains differ. Specifically, exogenous genes in E. coli predominantly exist as free plasmids, whereas in yeast expression hosts, these genes are typically integrated into the chromosomes. Consequently, these fundamental differences necessitate variations in the testing items and release standards applied to E. coli and yeast cell banks.

Yaohai Bio-Pharma has over a decade of experience constructing microbial cell banks, including those of E. coli and yeast. Leveraging the robust and compliant GMP (Good Manufacturing Practice) system, Yaohai Bio-Pharma has a comprehensive one-stop solution for strain bank construction. and has successfully delivered over a hundred certified and qualified strain banks to clients worldwide. From extensive experience, Yaohai Bio-Pharma has explained the key considerations in the release testing of E. coli and yeast strain banks.

Differences between Bacteria and fungi

E. coli belongs to bacteria, while yeast belongs to fungi. These two organisms exhibit distinct colony morphologies and biochemical characteristics. For example, the Gram staining method is suitable for identifying E. coli but not for identifying yeast. Secondly, at the genetic level, bacteria are characterized by their conserved 16S rRNA sequences, whereas fungi possess 18S rRNA and Internal Transcribed Spacer (ITS) regions. Conducting 16S or 18S combined with ITS sequencing for bacteria or fungi, respectively, can rapidly identify microbial species information. Furthermore, E. coli is susceptible to contamination by bacteriophages (viruses that attack bacteria), so it is recommended to perform bacteriophage detection when releasing E. coli cell banks.

Differences in the existence forms of exogenous genes

The production of recombinant biological products is generally based on engineered bacteria after modification, which are usually microbial strains with exogenous genes. The existence forms of exogenous genes in E. coli and yeast expression systems are different. Exogenous genes usually exist in the form of free plasmids in E. coli, while the yeast expression system integrates the target gene into its chromosome.

Differences in release testing between E. coli and yeast

Based on the previous characteristics, the primary differences in release testing items between E. coli and yeast cell banks lie in colony morphology, biochemical properties, bacteriophage detection, and exogenous gene identification.

Drawing from an in-depth understanding of ICH Q5D, international regulations, as well as pharmacopeia, and over a decade of experience in submissions for both E. coli and yeast, the Yaohai Bio-Pharma QC platform has established comprehensive testing procedures and release standards. Yaohai Bio-Pharma has forged strong partnerships with authoritative institutions internationally, ensuring that our testing methodologies and quality standards align with the submission requirements of FDA, EMA, NMPA, TGA, and other regulations.

Below, Yaohai Bio-Pharma has thoughtfully summarized the specific differences in release testing between E. coli and yeast for your convenience.

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