Laboratory-scale evidence for lightning-mediated gene transfer in soil

Area of Science:

• Microbiology
• Environmental Science
• Genetics

Background:

• Electrical fields and currents can induce bacterial membrane permeabilization, facilitating DNA uptake.
• Natural environments experience electrical perturbations from phenomena like lightning.
• Bacterial transformation is a key mechanism for genetic diversity and evolution.

Purpose of the Study:

• To investigate the possibility of natural bacterial electrotransformation induced by lightning.
• To determine if lightning-mediated electrical currents can facilitate DNA transfer in soil bacteria.

Main Methods:

• Soil microcosm experiments were conducted using Escherichia coli DH10B as the recipient strain.
• Laboratory-scale lightning was simulated to induce electrical perturbations in the soil.
• Transformation was assessed by the incorporation of antibiotic resistance genes from plasmid pBR328.
• Controls included identical setups without lightning exposure and simulated electrical fields without current.

Main Results:

• Bacterial transformation, evidenced by antibiotic-resistant clones, was observed only after soil exposure to laboratory-scale lightning.
• Lightning-induced electrical field gradients and current densities mimicked those of natural lightning.
• No antibiotic-resistant clones were detected in control groups lacking lightning exposure.
• Simulated storm cloud electrical fields, without current, did not result in detectable transformation.

Conclusions:

• Lightning-mediated electrical current injection can locally enhance bacterial transformation in soil.
• Natural electrotransformation may be a significant mechanism driving bacterial evolution and adaptation.
• This study provides evidence for a novel natural gene transfer mechanism influenced by geophysical electrical events.