Heteroduplex resolution using T7 endonuclease I in microbial community analyses

Area of Science:

• Molecular biology
• Microbial ecology
• Genomics

Background:

• Molecular techniques like PCR are crucial for studying unculturable microbes in ecological systems.
• PCR amplification of mixed DNA communities can generate artifacts, primarily heteroduplexes.
• Heteroduplexes can compromise the accuracy of microbial community structure analysis and genomic library construction.

Purpose of the Study:

• To evaluate the efficacy of T7 endonuclease I in resolving heteroduplexes formed during PCR amplification of microbial DNA.
• To improve the accuracy of microbial community analysis by preventing artifacts in genomic library construction.

Main Methods:

• Amplification of the 18S rDNA gene from soil microbial community DNA using PCR.
• Digestion of PCR products with T7 endonuclease I.
• Comparison of digested and undigested PCR products for heteroduplex formation before cloning.

Main Results:

• T7 endonuclease I digestion (10 U/microgram DNA) effectively eliminated heteroduplexes from amplified 18S rDNA.
• Approximately 10% of screened recombinants contained heteroduplexes without T7 endonuclease I treatment.
• The inclusion of T7 endonuclease I digestion ensured the generation of desired clones only.

Conclusions:

• T7 endonuclease I is a valuable tool for removing heteroduplex artifacts from PCR products of microbial communities.
• This digestion step significantly enhances the reliability of genomic library construction for microbial community analysis.
• Implementing T7 endonuclease I treatment is recommended to ensure accurate downstream molecular analyses.