Scientists
have discovered that water is teeming with literally thousands more
microscopic creatures than previously thought - many of them still largely
unknown. "Only about one in ten water-borne bacteria have even been
identified," says Daniel Hoefel, of the Cooperative Research Centre for
Water Quality and Treatment in Australia. "There are several million
species which we know by name, but the vast number of creatures that live
in our water are still unknown - we haven't named them, described them, or
discovered anything about their behaviour."
According to Hoefel, this is about to change. Some ingenious lateral
thinking has given water researchers a novel high-speed means of coming to
grips with the teeming microbes. "The main reason that we haven't been
able to identify all these microbes is that they are very hard to grow in
a laboratory culture," he says.
Hoefel and his colleagues at the Australian Water Quality Centre, in
conjunction with the University of South Australia, had the idea of using
a piece of hospital equipment known as a flow cytometer to assess water
quality. A flow cytometer has until now mainly been used for examining
human and animal blood cells, says Hoefel. "We found that by applying a
stain to water samples, the active bacteria glow under the laser beam of
the flow cytometer, and each individual cell is counted as it passes
through the beam," he says. "This means that we can count up to a thousand
bacterial cells per second," says Hoefel. "We can take a sample, treat it
with the dye or stain, count hundreds of thousands of bacteria, and have a
result within an hour of receiving the sample."
"Now we can assess whether the process is removing and inactivating all of
the bacteria, not just those that are culturable; in other words, we can
now accurately monitor the efficiency of water treatment plants and
understand the challenges involved in water treatment in a way which was
not previously possible." "We have also found that the water treatment
processes currently being used in Australia are effective in removing or
inactivating bacteria", he said. "The benefit of our new technique is that
it is easier to use and more accurate for monitoring the status of our
water supplies to our treatment facilities".
Hoefel hopes that due to the convenience and accuracy of the new test it
can be adopted in parts of the world where water quality monitoring has
previously been difficult. "Portable in-field flow cytometers have
recently been developed," says Hoefel, "but in most cases a sample can
readily be sent to a laboratory for assessment." "Apart from the flow
cytometer, the actual assay itself doesn't require any special equipment
other than a few pipettes for working with each sample," he says.
Read the Chymical Wedding List - bonus feature in Issue 71 of Elemental Discoveries; we've also got a new feature listing the elemental discoveries timeline.