Soil Sampling: A bacteriophage is to a tube of dirt as a human being is to ______ _____________.

A student question I received this week by e-mail:

In regards to our soil samples, would it be best to collect them in the morning or can we do it today?

I’ve mapped out all of my places, I just want to get the best quality sample and don’t want to damage any phages that (hopefully) lurk within by collecting too far in advance.

My off-the-cuff-answer:

Great question! 

You can gather your soil sample any time between yesterday and Wednesday. The difference in being in a tube and being in the soil from the perspective of a phage is probably undetectable. It’s like if our solar system is in our galaxy or has been transported to another galaxy! We won’t know the difference.

The student is probably thinking: but, is it REALLY like that? I was wondering several days later as well… is it REALLY like THAT?

A bacteriophage is many orders of times smaller than we are. This sounds a bit abstract but there is a beautiful and fascinating illustration of the scales of nature at I could easily spend an entire day going through this demonstration so do take the time to click on that link and see it.

Let me give you a few examples to illustrate the scale at which a bacteriophage exists and how this differs from our own perceptions. I will use the illustrations I mentioned from Cary and Michael Huang throughout.

This is a bacteriophage and the things that are roughly its size:Scale of Bacteriophage

A particle of clay is slightly larger than this scale. A tube of dirt is very literally, an immense landscape. In fact, just to imagine how big that is, we can compare the tube of dirt to a ruler. A ruler is 6 orders of magnitude larger than the bacteriophage. That is, if the bacteriophage is = 1, the tube of dirt is 10x10x10x10x10x10 larger or : 1,000,000 times larger. For comparisons sake, we can ask “What is 6 orders of magnitude larger than a human being? New Zealand is just about 6 orders of magnitude bigger than a person.

Scale of 0 human

New Zealand off the coast of France.

*For non-kiwi readers of this blog: this is not actually the location of New Zealand on a map. Apologies for any confusion.

So, more accurately perhaps I should have said that if New Zealand was picked up and transported to ANOTHER spot on Earth, say… cozied up to Europe, that would not be very obvious to you and I immediately. In fact, the predators and prey that were transported along with us would continue to play a much larger role in our lives than our proximity to Spain or the UK (and by prey in this context I mean “fish and chips” and by predators I actually mean “landlords”).

We are very clever however and we would figure this out eventually, but it would take a little while.

However, instead of saying something about the size of a person, I said something about moving our solar system into another galaxy. I am as astonished as you are to have checked this out and it’s basically right. The Kuiper Belt is the region of our solar system that is outside of the planets. In the Scales demonstration, the Kuiper Belt is hovering at about 1013 .

Kuiper beltThat is, 13 orders of magnitude larger than a human. At 6 orders of magnitude larger, we find whole galaxies. In fact, the estimated diameter of our galaxy is very close to 6 orders of magnitude difference. Well, a multiple of 100 off of 6 orders of magnitude at: 1021   apparently.10 21 galaxy

It really IS like our solar system being moved into another galaxy (during the day). We are conscious so, we would notice that the constellations had changed if we had been paying attention. Phages? Phages are not known for their outward signs of consciousness. So, what is the moral of the story?

“Sample the soil at will. Your PHAGES will not know that something is ‘up’?”

“Heather is always right?”

“Size does matter?”

“The internet is full of wonderful demonstrations and we should all be grateful to live in such a creative and generous time?”

This is an enquiry-based course with a strong “choose your own adventure” flavour to it so I will leave that question as an exercise for the reader.


About drhhnz

Microbiology, Evolution and Bacteriophages. Lecturer, Institute of Natural and Mathematical Sciences. Massey University. Superhero name: Microbiology Girl. Auckland, New Zealand · Twitter: drhhnz
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2 Responses to Soil Sampling: A bacteriophage is to a tube of dirt as a human being is to ______ _____________.

  1. Nikki says:

    Mind blown once I zoomed past the nanometer scale and then whoosh back up to the scale of planets and solar systems. Loved the use of random things like Rafflesia too and total human height. Rad. Thanks HH.

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