Effect of cellular physiology on PCR amplification efficiency

Area of Science:

• Microbiology
• Molecular Biology
• Biotechnology

Background:

• Cellular physiology, influenced by culture conditions, can introduce bias in polymerase chain reaction (PCR) amplification.
• This bias can lead to non-representative population profiles, hindering accurate molecular analysis.

Purpose of the Study:

• To investigate how different physiological states of cells affect PCR amplification.
• To determine if DNA extraction prior to PCR can mitigate amplification bias in mixed populations.

Main Methods:

• Constructed two Pseudomonas putida nahR alleles differing in a 31-bp inverted segment within pUC19.
• Coamplified whole cells under various conditions (stationary phase, temperature shifts, stress) with a control strain.
• Analyzed PCR products using restriction analysis to assess relative amplifiability.
• Compared results with and without prior plasmid DNA purification.

Main Results:

• Cells in stationary phase showed improved amplifiability.
• Growth at 42°C did not significantly alter amplifiability compared to 37°C.
• Sublethal tetracycline or minimal medium growth reduced PCR target amplifiability.
• Pre-purification of plasmid DNA eliminated coamplification bias.

Conclusions:

• Physiological state significantly impacts PCR amplifiability of whole cells.
• PCR amplification of mixed populations without DNA purification can be unrepresentative.
• Including a DNA extraction step is crucial for accurate representation of mixed microbial populations.