The time and cost required to make a plasmid

Posted by Jennifer Tsang on Sep 11, 2018 9:48:42 AM


Have you ever wondered how long it takes to make a plasmid? Or have you thought about how much total time you spend in the lab cloning before you can start on your experiment? What about all the reagents you need to order? Sometimes, it feels like an eternity of cloning, waiting, and repeating before you can finally dive deep into experiments.

Since one million plasmids shared is upon us at Addgene, we started wondering, just how much time and money do researchers spend cloning? How much does material sharing speed science?

How much time does it take to make a plasmid?

Figure_1_poll_results-01

This question sparked much debate around the office so we took to social media to see if we could come to a consensus. Though waiting is one of the greatest time sinks in molecular biology (or many other biological experiments, for that matter), we were interested in finding out the total hands-on time for cloning design, PCR, insertion in the backbone, transformation into bacteria, plasmid preps, and sequencing. This “total hands-on time” per plasmid assumes only one plasmid is being made at a time and that the correct clone reveals itself the first time.

We amassed a total of 120 votes on Twitter and also polled our Addgenies and found strikingly similar trends about perceived plasmid cloning times.

At the same time, John Doench, an Addgene Blue Flame depositor, calculated the time to make a plasmid to help us settle the debate. At the Broad Institute, Doench’s lab has created hundreds of thousands of plasmids either en masse for genome wide screens or for the more traditional “one plasmid for one problem” scenario.

He did the math and came to the conclusion that it takes 5 hours of hands-on time to make a plasmid. The breakdown of his calculations are below.

Calculations_table-01

Are you surprised? While the time calculated here is for a simple insertion of a PCR product into a vector, the time it takes to make a plasmid could increase dramatically if you are piecing together several PCR products together.

How much does it cost to make a plasmid?

Doench also calculated the cost of making a plasmid in terms of consumable reagents only. Each plasmid created carries a $115 cost in materials excluding any restriction enzymes or vector purchases (see above). With the addition of the restriction enzyme and a vector purchase, the cost could go up by a few bucks, or a hundred, respectively just for reagents. But if you factor in the cost of personnel and overhead costs, the “true” cost of making a plasmid could more than double.

Five ways to decrease plasmid production time and cost

  1. Obtain your plasmids from a repository such as Addgene. Since we verify deposited plasmids by sequencing at Addgene, you can also be sure that the plasmids you receive are indeed what you think they are. Plasmids also ship within 2-3 business days which ensures you get the correct reagents quickly.
  2. Ask the PI or corresponding author of the published plasmids. This is a great way to network and build collaborations while obtaining the reagents you need. But unfortunately, this method does not have a 100% success rate and may require repeated inquiries.
  3. Think about previously constructed plasmids in your lab. For example, if you’ve cloned your gene of interest in the past for another purpose, see if recycling it for your next construct will save you time.
  4. Consider some alternative cloning strategies over the traditional PCR/digest/ligate methods. While methods such as Gibson assembly can save you time when creating complicated constructs, you may also need to balance speed with cost.
  5. Create several constructs at once. Instead of making one plasmid at a time, try to group the construction of several plasmids in parallel. That way, you can run one PCR, one gel, etc. for all plasmids at once.

We’re very excited to reach one million plasmids shared. Reagent sharing saves both time and money and based on Doench’s calculations, Addgene and the scientist who have deposited their plasmids at Addgene have saved the scientific community over $50 million dollars, at a generous minimum. In terms of total time Addgene has saved thus far, multiply 5 hours per plasmid by a million. Five million hours. According to Doench, "5 million hours, in case you were wondering, is the amount of time between the years 2018 and 1448, which is when the Inca were starting to build Machu Picchu, and Leonardo da Vinci hadn't been born yet." We’re proud to have such a positive impact on the scientific community and are eager to continue accelerating science through the next million plasmids and beyond!

 


Additional Resources on the Addgene Blog

Resources on Addgene.org

Topics: Lab Tips, Plasmid Cloning

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