Adaptive Laboratory Evolution

     
 
 

Adaptive Laboratory Evolution (ALE) is a frequently used method in biology to study molecular evolution and adaptive changes in microbial populations over a long term period of time and under specific growing conditions. With the recent breakthroughs in next-generation sequencing technologies and associated low-costs in sequencing, ALE is becoming more popular as a tool for biotechnology.

   
 
 

A critical requirement of this method is the aeration of cultures, traditionally done with a magnetic stir bar mixing a flask inside an incubator to generate a vortex on an orbital shaker platform. However, these traditional methods are impracticable for doing in a high-throughput manner for several reasons:

  • Traditional stir plates can only mix one vessel at a time; each additional sample would require its own stir plate.

  • As the cultures must be heated, the stirring needs to be inside an incubator. There would be space constraints especially if each sample needed its own stir plate.

  • The cultures must be sampled regularly (ideally every 10 – 15 minutes) over a period of 24 – 36 hours. When using a laboratory technician, for practical purposes, cultures are sampled once every couple of hours.

  • Orbital shakers are not compatable with Automation Platforms.
   
 
 

By using a robotic liquid handler, the preparation and sampling of the cultures can be automated. However, the aeration of the cultures in a high-throughput manner is still a significant hurdle to overcome, especially when considering the limited space allowed by a liquid handler.

     
 
 

V&P Scientific helped one of our customers develop a high-throughput method for Adaptive Laboratory Evolution. V&P designed and built a combination heater/mixer integrated into the Tecan Evo liquid handler. A graphite heat block, VP 741GZ-64, was used for incubation, allowing for up to 64 tubes (50ml conical bottom) to be used. A Magnetic Tumble Stirrer, VP 710T-SM, was used to stir all 64 samples with a single stirrer unit. Each tube utilized a 24mm diameter stir disc, and when powered by the tumble stirrer, generated a vigorous vortex to the bottom of the tube, thus assuring the maximun transfer of oxygen into the growth medium.

   
 
 

Our customer has written an earlier white paper to report their findings for Adaptive Laboratory Evolution when using V&P’s magnetic tumble stirrer.


Click Here for the report.