Summer Sciencing! – Investigation One – The Microbiology of Water

Scanning electron micrograph of Escherichia coli

Dear Readers, I might have mentioned that I was pining for some science, so I’ve signed up for the Open University Summer Science School. My first investigation is, very topically, into water quality, and possible faecal contamination of some imaginary water sources.

Humans and many animals normally live happily with Escherichia coli in their intestines, where it causes no problems at all. However, there are some forms of E.coli which cause disease, and amongst the worst are the enterohaemorrhagic bacteria, which include a nasty bug called E.coli 0157. Not only does this cause the usual bloody diarrhoea and cramps but, in the worst cases, it can damage the blood vessels in the kidneys, leading to kidney failure and even death. My mission on this occasion is to look at water samples from three different areas – two wells and a bathing area – from an imaginary town where people are showing symptoms of E.coli-induced diarrhoea, and first of all to see if there’s been a deterioration in water quality using a technique called the Aerobic Colony Count (ACC).

Lots of different kinds of organisms can live in water, but most of them are rendered harmless in the Global North by chlorination or UV light treatment of the water we drink (clearly not the water that we might swim or paddle in however, as recent sewage releases into rivers and the sea have shown). However, not everyone is so lucky, and so the water that they drink can contain all sorts of organisms. Some of them, known as environmental organisms, live naturally in water, and so while no one wants to drink microorganisms they are usually harmless (and often can’t survive at the temperatures in the human body). Others, such as E.coli 0157, are pathogens, which can survive in the water but really take off when they reach the perfect environment of the human gut.

The Aerobic Colony Count takes a sample of water, and incubates it at two different temperatures – 22 degrees Centigrade and 37 degrees Centigrade. At 22 degrees, any environmental organisms are likely to multiply, at 37 degrees we should see an increase in pathogens if any are present. An increase in environmental organisms indicates a general decrease in water quality, but an increase in pathogens indicates potential faecal contamination.

So, all of this sciencing takes place in an online laboratory (so there’s no danger of me contaminating half of East Finchley with an accidental sample spillage) but all the same I am channelling  my inner Public Health professional and am thoroughly enjoying all this messing about with (virtual) test tubes and petri dishes. Once I’ve taken samples from the wells and the bathing area, it will be interesting to see if there’s a clear indication of where the contamination is coming from. Once we know, I can use some other techniques to try to identify which organisms are involved, and in particular if the dreaded E.coli 0157 is implicated.

Now, where’s me white coat?


2 thoughts on “Summer Sciencing! – Investigation One – The Microbiology of Water

  1. Sharon

    Hi, I’ve been making my own contribution to citizen science recently with the Big Butterfly Count in our back garden. There have been Red Admirals, Small Blues, Peacocks, Gatekeepers, and a small moth that sat still long enough for me to recognise (but I can’t remember the name or find a picture anywhere yet!) Alas the most common butterflies have been Small and Large Whites – my Brassicas!
    I find it encouraging that we ‘ordinary people’ can participate in these sort of projects and make a difference, however small.

    1. Bug Woman Post author

      It’s been such a great year for butterflies – I was reading that Butterfly Conservation think that Red Admiral numbers have gone up by 400% this year (though they are migratory (or at least some of them are) so they’ve probably been driven further north in search of food/cooler temperatures. But it is a real joy to see them, for sure. And yes, citizen science is so useful for contributing to the big picture of what’s going on year to year. I’m glad you enjoy it as much as I do!


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