Lambda (λ) phage based cloning vectors are used commonly in molecular biology. The cloning of single genes (< 2kb) is usually done using plasmids. However, for large DNA molecules can be injected in host bacterial cell by bacteriophages.

Based on size of DNA lambda vectors are divided into two types.

  1. Lambda replacement vectors
  2. Lambda insertion vectors

EMBL4, EMBL3, λ DASH are examples of lambda replacement vectors, whereas, λgt10 and λgt11 are example of insertion vectors.

Advantages of using Lambda Phages

Lambda vectors are one of the most powerful and popular tools for molecular cloning. Following are the reasons that contribute to it:

  • Availability of a wide range of lambda vectors
  • Rapid isolation of lambda DNA
  • High efficiency of commercially available in vitro packaging extracts
  • Efficient  in vitro amplification of DNA via the polymerase chain reaction

Libraries constructed in lambda vectors (Figure 13) are screened easily with antibody or nucleic acid probes since several thousand clones can be plated on a petri dish.

Figure 13. Phage display cycle
Figure 13. Phage display cycle