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In Ireland, bacterial contamination of water is a national
concern, with the Environmental Protection Agency reporting
that over 25% of groundwater samples were contaminated with
E. coli in the 2004 to 2006 period.
E. coli is the most important indicator used in Ireland
and its presence indicates that water is unfit for human consumption.
It has long been thought that E. coli can only survive
for short periods of time in the environment - hence, its
almost universal use as an indicator of recent faecal contamination
of waterways.
However, new research investigating pathogen survival in
Irish soils - conducted by Teagasc Johnstown Castle Environment
Research Centre and NUI Galway - has found that E. coli
can become integrated into the indigenous microbial community
in soils and survive for more than nine years, considerably
longer than scientists initially thought.
This has important implications for the indicator status
of E. coli, suggesting that the presence of E. coli
in surface or groundwaters may not be indicative of recent
faecal contamination, explains researcher Fiona Brennan in
TResearch, the Teagasc Research and Innovation magazine.
It also suggests that E. coli persistence may be
favoured in some soil types and these soils may represent
a greater risk of bacterial leaching, she explains. Research
conducted at Johnstown Castle has investigated bacterial transport
in grassland soils both in situ at field sites and
in field lysimeter (soil monolith) units.
In conjunction with NUI Galway, Teagasc researchers are now
using proteomics to investigate the unique properties of E.
coli that allow it to persist in the soil for such long
periods. Initial findings have found that the environmentally
persistent E. coli produce specialised proteins, including
cold shock and stress response proteins,
which may assist in the survival and growth of the organism
at lower temperatures.
E. colis ability to survive for prolonged periods
of time in soil may compromise its use as the sole indicator
of faecal contamination of water.
The full text of the article, which appears in TResearch,
the Teagasc Research and Innovation magazine, can be viewed
online
This research is funded by Teagasc, IRCSET and SFI and is
a collaborative project between Teagasc and NUI Galway.
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