Relic DNA FAQ

Q. Do you have a more detailed Relic DNA protocol?

A: The Relic DNA protocol was developed nearly a decade ago during my postdoctoral training in the Fierer lab. While we no longer develop or use these methods in our current projects, below are some additional details.

Available Resources

  • Published methodology can be found in our papers here and here.

Equipment Notes

  • Light Source: We originally used these specialized lamps (now discontinued):

    • Activator lights from Biotium were also an option (no longer available)

    • When developing an alternative light source, you'll need to validate sufficient PMA activation. Any bright light will likely work.

  • Temperature Control: Critical for process integrity

    • All experiments maintained between 16-23°C

    • I used a cooling incubator to offset heat generated by lamps

Step-by-Step Process

  1. Preparation:

    • All steps performed in darkness until light exposure. I used a red lamp to see in the room as red wavelengths don’t activate PMA.

    • I used these transparent tubes

    • The soil to buffer ratio is crucial - 1% soil worked best for our soils since dense slurries prevent sufficient light contact. You may need to optimize this for your samples.

  2. Processing:

    • Attached tubes to moBio's vortexer adapter for 15 mL tubes

    • Placed vortexer under 650W light

    • Shaken at just over half maximum speed for ~5 minutes in darkness (allows PMA to bind to susceptible cells)

    • Exposed to 5 cycles of 30s light/30s darkness while continuing to shake. Light/dark cycling minimized heat exposure (constant heat will damage equipment)

    • Shaking during exposure ensures even light contact with suspended soil

    • After light activation, the soils are stable and can be frozen or exposed to light with no ill effect.

Additional Considerations:

  • For low biomass samples, optimization will be required

  • Testing is necessary to determine whether you have sufficient biomass

Note: These details are provided for reference purposes only. As our lab has moved on to different projects, we may not be able to provide additional support for this technique.