Establishing Best Practices to Minimize Waste in a Conservation Genetics Lab

I am, among other things, a conservation geneticist. What that means is that I use the tools of molecular ecology and population genetics to make observations about species and populations in at-risk ecosystems, assess the status of anthropogenically disturbed populations, and generate data that has direct applications to conservation and management issues. Essentially, the only difference between what I do and what a population geneticist or molecular ecologist does is the motivation—I select systems to work in that have a high conservation priority.

This motivation leads to a constant intellectual conflict at the bench. The tools of molecular ecology—PCR, gene sequencing, and, more frequently, high-throughput sequencing—are waste intensive. In order to avoid cross-contamination and practice precise, clean, technique, we use thousands of tiny plastic consumables every day. These come in the form of pipette tips, sterile packaging material, micro-centrifuge tubes, and numerous other plastic widgets. Often, because of the biohazard potential, these consumable cannot be recycled.

So we have a problem. As a conservation geneticist, we need these tools to produce the data necessary to make wise conservation and management decisions. As a sustainability minded individual, I find the massive daily accumulation of plastic waste inexcusable. Do we just accept this waste as the cost of conservation genetics? I believe that the answer is no. I think we can and should develop best practices to minimize the amount of plastic waste produced by a molecular lab while maintaining good, sterile technique. I would like to propose four guidelines, based off the principles of Reduce, Reuse, and Recycle, for minimizing waste in a conservation genetics lab.

1. Select appropriate  consumables. You can buy pipette tips that come individually racked in their own containers, ready to use right out of the box. You can buy racked tips that require a reusable container. You can buy un-racked tips in a large bag. All of these options have advantages and drawbacks. If you’re only doing a few plates of PCR, a few boxes of tips may be all you need. If you’re stocking an entire lab, you will probably be ordering millions over the years. Pay attention to how your consumables are packaged and what that packaging means for long-term waste reduction. Racking un-racked tips is time consuming but low waste. Pre-racked, already in container, tips are high waste time savers. The same goes for other consumables. Do you 96-well plates come individually wrapped or packed in bulk? Do you need pre-sterilized micro-centrifuge tube right out of the box, or can you autoclave them in bulk when they arrive?

Packaging is, by far, the easiest issue to address. By selecting appropriate, waste-minimizing consumables you can cut out the majority of the excess waste produced in you lab.

2. Audit your workflow. When you sit down at a bench, pay attention to the order in which you do things. Audit your workflow to determine how many consumables you use and how many you actually need. Here’s an example: Let’s say you’re prepping 96 individuals for PCR. You start by transferring DNA template from your sample archive to a 96-well plate—96 pipette tips. Then you prepare you master mix, one fresh tip for every reagent—7 pipette tips. Finally, you add the master mix to you DNA’s, being careful not to cross contaminate your samples—96 pipette tips. In total, you’ve used 199 pipette tips, that’s not a lot, but imagine doing this reaction several times a day, which is exactly what many molecular labs do.

So, in this workflow audit, where is the waste? You need a fresh tip for every DNA, otherwise you’ll contaminate you samples, so those 96 tips are essential. The same goes for the 7 to make the master mix, although you could reduce those to 1 if you pre-aliquot a bulk master mix that includes multiple reagents, which only works if you’re planning on running the same reaction many times. Let’s split the difference and call that 4. That brings us to the final step: adding the master mix to the DNA’s. In the original workflow, this consumed 96 tips. In a reduced waste workflow, this uses 1. How? Do it first. Remember, you’re DNA’s are the potential contaminants. If you pipette your master mix into the 96-well plate first, and then add the DNA’s, you can use  a single tip. That brings us down from 199 tips to 101 tips. 98 may not seem like a lot, but over the course of my thesis, I probably set up this exact reaction 1500 times. That’s over 147,000 pipette tips that didn’t find their way into the trash.

This is just one small example, but by auditing your workflow you can identify major sources of waste. Small, simple changes to the order in which you perform tasks can have make a big difference in the amount of plastic waste generated by your lab.

3. Recognize what can and can’t be reused. Despite what the manufacturers say, many consumables can be reused. A little cleaning goes a long way. If your tips are autoclavable, and you’re not working with hazardous materials, tips can be used and cleaned several times before they begin to break down (although, I’d recommend using reused tips for less precision-intensive set-ups). Spin columns can be acid washed and reused two of three times before the membrane starts to degrade. Even little things help. Can the micro-centrifuge tube be reused? If that falcon tube just held ethanol, do you really need to throw it out? Can you use the plastic re-sealable bags that 96-well plates come in to store other consumables?

Some items can be cleaned, some cannot. Being familiar with your materials and procedures can help you determine what is really waste and what simply needs a good cleaning.

4. Re-purpose used consumables. Finally, just because something has reached the end of its useful life in the lab, doesn’t mean that it is de-facto ready for the trash. Lab member should be encouraged to find creative re-uses for some consumables. From storage containers to art projects, lab consumables can be given a second life. Just make sure there’s no hazardous material risk.

I’m waiting for the day when someone figures out how to turn used pipette tips into raw material for a 3D printer. Then we can leave many of these concerns behind.

I’d like to open this discussion up to anyone working in conservation genetics, molecular ecology, population genetics, and related fields to discuss possible solutions, tips, and techniques that help minimize the amount of waste produced by molecular labs. Consider this a digital workshop on establishing guidelines and best practices for a low-waste genetics lab.