DH10B are an engineered strain of Escherichia coli (E. coli) that are highly efficient at molecular cloning. DH10B cells are particularly adept at handling large DNA fragments, generating genomic or cDNA libraries, and processing methylated DNA from mammalian cells.

Sometimes it is really helpful to be a specialist. Think about building a house, for example. In addition to a general contractor there are all kinds of specialists involved: framers, plumbers, electricians, painters, etc.

There are also specialists in the molecular world. Bacteria are impressive molecular builders that are leveraged to construct useful biomacromolecules for research and biotechnology purposes. Different strains of bacteria excel at building different types of proteins and nucleic acids.

BL21 cells are great at producing recombinant proteins, whereas DH5a and DH10B strains excel at generating plasmid DNA. Even between DH5a and DH10B, however, they have their own niches in terms of what types of DNA each is really good at crafting.

DH10B are an engineered strain of Escherichia coli (E. coli) that are highly efficient at molecular cloning. DH10B cells are particularly adept at handling large DNA fragments, generating genomic or cDNA libraries, and processing methylated DNA from mammalian cells.

 

Article Contents

Special Features of DH10B cells

What are GB10B^TM cells?

Electrocompetent vs chemically competent cells

Should I use GB10B or GB5-a for my cloning?

Related Resources

References

 

Special Features of DH10B cells

Why are DH10B such a good E. coli strain for DNA cloning? Like DH5a, DH10B cells also have mutations in the genes that encode for the enzymes RecA and EndA (Yale University, 2020). These mutations inactivate the RecA and EndA enzymes, meaning that your plasmid won’t get incorporated into the bacterial genome by RecA or get degraded by EndA (Figure 1).

Figure 1. Mutated EndA nuclease enables DH10B to generate higher plasmid DNA concentrations (right).

 

However, DH10B cells also have an additional mutation that is not found in DH5a. DH10B cells have a deleted hsd operon, meaning they will not restrict nor modify methylated DNA.

Methylated DNA is DNA that has a slight modification. Biologically, this methylation modification is important for gene expression; it helps indicate if a particular gene should be expressed, or not (Figure 2)(Deaton & Bird, 2011).

Figure 2. DNA methylation (pink octagons) typically represses gene expression (Deaton & Bird, 2011).

 

But in the context of cloning, methylated DNA is potentially a nuisance. DH5a cells recognize methylated DNA as being foreign and will degrade the DNA thinking that it belongs to an invading pathogen.

DH10B cells, on the other hand, do not destroy methylated DNA since that hsd operon has been deleted. So, if you’re trying to clone methylated DNA, such as from human or other mammalian cells, then DH10B can use this DNA directly, whereas DH5a will have really low transformation efficiency. We’ll discuss this more in the last section comparing the two strains.

 

What are GB10B^TM cells?

The DH10B strain has that name because it was the 10^th strain engineered by the scientist Douglas Hanahan. As it turns out, that 10^th strain was one of the better ones at producing DNA plasmids, so that is why it is commonly used today (Hanahan, 1985).

GoldBio’s version of DH10B are called GB10B^TM cells, and they have the same mutations that we discussed in the previous section. Importantly, GB10B^TM E. coli cells are equivalent to DH10B. So, if your protocol calls for DH10B, you can confidently use GB10B^TM cells knowing that you are using the right strain at a great price.

 

Electrocompetent vs chemically competent cells

GoldBio sells a few different kinds of GB10B^TM cells. One of the main differences is whether they are electrocompetent or chemically competent. Electrocompetent cells use electroporation to transfer DNA into the cells, whereas chemically competent GB10B^TM use a mild heat shock for the same purpose.

If you want more details about the differences between electrocompetent and chemically competent cells, check out this article. One important difference to highlight is that transformation efficiencies tend to be higher for electroporation compared to chemical transformation (Aune & Aachmann, 2010).

If transformation efficiency is critical for your cloning, then you’ll definitely want to go with GB10B-Pro^TM electrocompetent cells. These have at least a twofold greater transformation efficiency, which can make a big difference for applications such as plasmid library construction.

 

Should I use GB10B or GB5-a for my cloning?

In our article on DH5a cells, we cover several common applications for molecular cloning, including:

• -      standard cloning
• -       blue-white screening
• -       DNA library assembly

GB10B cells can also be used for all of these purposes. And, in fact, GB10B-Pro^TM electrocompetent cells are the best choice for DNA library assembly. That’s because GB10B-Pro^TM have about a two-times higher transformation efficiency compared to GB5-a cells.

For standard cloning, where you’re just trying to get one correct plasmid, that two-fold difference usually won’t matter. But when constructing a DNA library, that increased efficiency means you will have roughly twice the number of different plasmids in your library (Figure 3).  

Figure 3. Low transformational efficiency is not crucial when cloning a single plasmid (left), but limits the diversity of constructs in a plasmid library (right).

 

Another difference between DH10B and DH5-alpha is that DH10B are better when you’re cloning large plasmids. DH5a will work fine when cloning regular sized plasmids, up to roughly 10 to 15 kilobases in length. If you’re cloning plasmids larger than that, then you’ll definitely want to go with DH10B cells which can clone plasmids that are hundreds of kilobases long.

Lastly, as mentioned in the DH10B section, these cells are capable of transforming methylated DNA such as from human and other mammalian cells (Grant et al, 1990). DH5a cells, on the other hand, will have really low efficiency with methylated DNA, and need another strain (like DH10B) to handle the methylated DNA first.

See Table 1 for a summary of the differences between DH10B and DH5a  cells.

Table 1. DH5a vs DH10B

	DH5a	DH10B
Standard Cloning	Yes	Yes
Plasmid Library		Yes
Large Plasmid		Yes
Methylated DNA		Yes

 

In summary, DH10B are a great choice for DNA cloning, especially when transformation efficiency is critical, or if you’re working with methylated DNA or large inserts.  GB10B^TM are the same as DH10B, so if you’re ready to start cloning, check out our reliable products below to help get you started in the lab. Alternatively, if you are still at the learning and planning stage, check out some of our related resources to learn more about competent cells, DNA plasmids, and blue-white screening.

 

Related Resources

Introduction to Competent Cells

Understanding Competent Cells for Bacterial Transformation

5 Key Features of Plasmids Explained

3 Methods for Verifying Your DNA Plasmids

Explain Alpha-Complementation and Blue-White Screening To Me Like I’m 10

How to Choose Competent Cells

What Are DH5a Competent Cells?

What Are BL21 Competent Cells?

 

References

Aune, T. E. V., & Aachmann, F. L. (2009). Methodologies to increase the transformation efficiencies and the range of bacteria that can be transformed. Applied Microbiology and Biotechnology, 85(5), 1301–1313. https://doi.org/10.1007/s00253-009-2349-1.

Deaton, A. M., & Bird, A. (2011). CpG islands and the regulation of transcription. Genes & development, 25(10), 1010–1022. https://doi.org/10.1101/gad.2037511

Durfee, T., Nelson, R., Baldwin, S., Plunkett, G., 3rd, Burland, V., Mau, B., Petrosino, J. F., Qin, X., Muzny, D. M., Ayele, M., Gibbs, R. A., Csörgo, B., Pósfai, G., Weinstock, G. M., & Blattner, F. R. (2008). The complete genome sequence of Escherichia coli DH10B: insights into the biology of a laboratory workhorse. Journal of bacteriology, 190(7), 2597–2606. https://doi.org/10.1128/JB.01695-07

Grant, S. G., Jessee, J., Bloom, F. R., & Hanahan, D. (1990). Differential plasmid rescue from transgenic mouse DNAs into Escherichia coli methylation-restriction mutants. Proceedings of the National Academy of Sciences of the United States of America, 87(12), 4645–4649. https://doi.org/10.1073/pnas.87.12.4645

Hanahan, D. (1985) in DNA cloning: a practical approach (Glover, D. M. ed.), pp. 109-135, Oxford University Press.

National Library of Medicine. What are genomic-clone libraries and how are they made? Accessed September 16, 2025. https://support.nlm.nih.gov/kbArticle/?pn=KA-05211

Nishiga, M., Qi, L. S., & Wu, J. C. (2021). CRISPRi/a Screening with Human iPSCs. Methods in molecular biology (Clifton, N.J.), 2320, 261–281. https://doi.org/10.1007/978-1-0716-1484-6_23

Oehlmann, N. N., & Rebelein, J. G. (2025). Generating Site Saturation Mutagenesis Libraries and Transferring Them to Broad Host-Range Plasmids Using Golden Gate Cloning. Methods in molecular biology (Clifton, N.J.), 2850, 251–264. https://doi.org/10.1007/978-1-0716-4220-7_14

Soares, M. B., Bonaldo, M. F., Jelene, P., Su, L., Lawton, L., & Efstratiadis, A. (1994). Construction and characterization of a normalized cDNA library. Proceedings of the National Academy of Sciences of the United States of America, 91(20), 9228–9232. https://doi.org/10.1073/pnas.91.20.9228

Yale University Coli Genetic Stock Center. (2020, July 17). Strain DH5a. https://web.archive.org/web/20200717104111/https://cgsc2.biology.yale.edu/Strain.php?ID=150015

Xiang, X., Corsi, G. I., Anthon, C., Qu, K., Pan, X., Liang, X., Han, P., Dong, Z., Liu, L., Zhong, J., Ma, T., Wang, J., Zhang, X., Jiang, H., Xu, F., Liu, X., Xu, X., Wang, J., Yang, H., Bolund, L., … Luo, Y. (2021). Enhancing CRISPR-Cas9 gRNA efficiency prediction by data integration and deep learning. Nature communications, 12(1), 3238. https://doi.org/10.1038/s41467-021-23576-0

 

 

 

 

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competent cells DH10B Cells Simon Currie

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