Hi Reader, can we be more sustainable in sterile environments or S2 environments?
Of course, we all have ideas, but turning them into reality is often more challenging.
Therefore, I want to provide you with some real-life examples.
As an advisor to institutes, universities, and companies, I have seen several examples. Here is one I especially like:
Today's Lesson: Case Report Microbiology
An example of a more sustainable practice
Number Of The Day
According to Campion et al., each of their scientists consumes about 15 kg of plastic waste per year just for cell culture work. Given their 5 scientists, that is over 1.8kg per week! However, it is possible to cut this consumption by a large fraction - without endangering sterility or time-sensitive steps. Therefore, let's see what a microbiology and cell culture lab can do to save resources and work more sustainably.
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An Example To Encourage You
I understand sustainability as an approach to making scientific workflows more efficient without fundamentally changing our science.
The goal is to save resources by rethinking how we conduct our experiments - this graphic should visualize the core principle of how I understand sustainability.
In my work as an advisor/consultant, one particularly strong example that comes to mind is from the Roslin Institute in Edinburgh.
Let’s look at one of their labs (also published here) to discuss in detail what sustainable practice can look like.
Establishing a Baseline
To find out where the biggest opportunities for sustainability lie, the most effective approach is to measure:
In this instance, plastic waste was suspected to be the main culprit. Therefore, a digital weight scale was placed close to the waste bin collection points.
Remember, don’t reinvent the wheel. There are several free resources available, such as guides on how to conduct waste audits, even on a large scale. One example is this guide from Stanford University. The graphic is from Seven Generations Ahead.
What’s more, three whiteboards were provided where people could measure and quantify the number of items they discarded.
However, let’s cut to the chase: after four weeks, 97 kilograms of plastic waste were produced by just seven researchers,
comprising more than 4,000 discarded items.
This enormous number already made it clear that plastic waste was one of the major concerns in this laboratory.
We will talk about take-back programs later, but just to give you a sense of the amount of plastic waste produced by scientists, watch this 4:38 min report about a colleague of mine - and note that they only accept certain types of plastic.
Of note, in companies this could easily be energy consumption or, especially in chemistry labs, reagents and chemicals.
What Can Be Done?
So what can be changed in an S2 environment that requires precision? Let’s start with my favorite example:
The first step was to distinguish which work really needed to be sterile and which did not, because much of the bacterial work did not have to be.
As a result, options for reuse were identified:
Petri dishes, jars and weighing boats reused
Bacterial colony work was changed to toothpicks and reusable inoculation loops
Experimental design was optimized
Conscious choosing of items, e.g., filter tips only when necessary
Conical tubes were washed, autoclaved and reused
Of course, behind the scenes there was more going on. For example, in some instances it was possible to replace non-autoclavable polystyrene plastics with autoclavable 15-milliliter Falcon tubes.
The key is to differentiate, instead of wasting money, time, and resources on unnecessary measures that do not contribute to quality.
Another great change was the introduction of the so-called drop technique.
At the top, traditional streaking is shown. Below, Chen et al. outline their approach. However, in 2015, Thomas et al. described single plate–serial dilution spotting as a similar yet more effective approach.
Instead of streaking bacteria out, one can drop them with a pipette onto the plate, thereby not only reducing plastic waste, but in some cases even enhancing the sensitivity of the assay.
Broader Changes
Two key points are worth highlighting:
A) Take-back programs are a solution that excites many scientists. Here, too, this was an option.
Although we have to be diligent about when these measures really make sense (because education and information about them are still limited) a program for uncontaminated plastic bottles and tip boxes was established. You can read more about others available here.
One question I get asked frequently when consulting: Yes, even though one works in an S2 environment, non-contaminated plastic items such as media bottles can often be recycled.
B) Upstream opportunities, for example, the reorganization of procurement. In other words, decentralized procuring helped promote bulk ordering and reduce shipments.
A very important point here is that companies differ in the amount of packaging waste and delivery habits, which can significantly reduce overall footprints.
The Results
All in all, in just four weeks, 43 kilograms of plastic waste were reduced. Extrapolated to a year, this would mean that 560 kilograms of plastic waste were saved.
This image is provided as an illustrative example of moving from streaking to drop plating for six conditions, each with six plated serial dilutions—reducing the setup from 36 agar Petri dishes, 36 spreaders, and numerous tubes and tips to just one Petri dish, one 96-well plate, and 36 tips. What went along with all of these changes, of course, was a heightened sensitivity of each individual scientist toward sustainability. This is why other apparently trivial measures, such as reusing items or switching to wooden toothpicks and metal inoculation loops, were implemented.
Over 1,300 plastic inoculation loops were saved. Similarly, more than 1,670 plastic tubes were saved, which altogether amounted to more than 1,500 pounds in savings.
This example clearly shows that even in environments labeled safety level 2, we can work more sustainably without compromising scientific precision.
Applying The Knowledge
Change is possible everywhere. Sometimes it just needs some expertise and encouragement.
Please note that waste production was monitored over several weeks. This is important - we do not perform the same experiments every week. A sufficiently long measuring interval is therefore necessary to properly trace changes.
What was needed for all of this, of course, was education and coordination.
From my own experience, I cannot emphasize this often enough:
Many people have concerns because they believe sustainability is a black-and-white change.
However, it's a process that happens stepwise in order to ensure safety.
Another point important to notice, however, is that sustainability savings are often greater than originally imagined.
Not only was plastic waste reduced, but since the waste was no longer autoclaved, common practice in safety level-2 environments, a significant amount of energy was saved as well.
The major challenge was the need for coordination, education, and the time investment for the sessions and cleaning of items.
However, some of that time was made up for through quicker practices such as the drop technique, as well as through reduced autoclaving of waste overall.
Again, sustainability incentivizes the optimization of workflows to save money and enhance the robustness of our work in the long run.
How We Feel Today
References
Campion, C., et al., 2025. Towards greener and more sustainable pre-clinical oncology research. BJC Reports, 3, Article 4. doi:10.1038/s44276-024-00115-0.
Alves, J., et al., 2020. A case report: insights into reducing plastic waste in a microbiology laboratory. Access Microbiology, 3(3), Article 000173. doi:10.1099/acmi.0.000173.
Penndorf, P., 2024. Reducing plastic waste in scientific protocols by 65% – practical steps for sustainable research. FEBS Letters, 598(11), pp. 1331–1334. doi:10.1002/1873-3468.14909.
Chen, C.Y., et al., 2003. A 6 × 6 drop plate method for simultaneous colony counting and MPN enumeration of Campylobacter jejuni, Listeria monocytogenes, and Escherichia coli. Journal of Microbiological Methods, 55(2), pp. 475–479. doi:10.1016/S0167-7012(03)00194-5.
Thomas, P., et al., 2015. Optimization of single plate–serial dilution spotting (SP-SDS) with sample anchoring as an assured method for bacterial and yeast CFU enumeration and single colony isolation from diverse samples. Biotechnology Reports, 8, pp. 45–55. doi:10.1016/j.btre.2015.08.003.
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