Natural Pseudomonas sp. strain N3 in artificial soil microcosms

Area of Science:

• Environmental microbiology
• Molecular biology
• Soil science

Background:

• Horizontal gene transfer (HGT) is crucial for microbial evolution and adaptation in soil ecosystems.
• Natural electrotransformation (NET), or lightning transformation, is a proposed HGT mechanism involving electric fields.
• Understanding NET's scope and influencing factors is vital for soil microbial ecology.

Purpose of the Study:

• To quantify the soil volume affected by NET using a laboratory-scale lightning system.
• To investigate the impact of DNA characteristics (amount, size, purity) and soil residence time on NET efficiency.
• To determine the relationship between electrical field gradient and NET frequency.

Main Methods:

• Utilized a laboratory-scale lightning system to apply variable electrical fields to soil.
• Employed Pseudomonas sp. strain N3 as the model organism for electrotransformation studies.
• Assessed NET frequencies under varying conditions of DNA parameters and electrical field strengths.

Main Results:

• NET was estimated to affect soil volumes ranging from 2 to 950 m³ per lightning strike.
• NET frequencies varied significantly based on DNA purity and soil residence time, from 10⁻⁸ to 4 x 10⁻⁷.
• Higher electrical field gradients (2.3–6.5 kV/cm) correlated with increased NET frequencies (1.7 x 10⁻⁴).

Conclusions:

• NET is a plausible horizontal gene transfer mechanism in soil, influenced by electrical field intensity and DNA quality.
• The efficiency of NET is dependent on DNA integrity and its interaction with the soil matrix.
• This research provides quantitative insights into the environmental conditions conducive to NET in soil ecosystems.