Rights: © Copyright. University of Waikato. All Rights Reserved. Published 9 September 2016 Download

ESR scientist Dr Brent Gilpin explains that bacteria are everywhere, and there are billions of them around us all the time. Only a small number are harmful to health, and it is identifying those in a background of harmless bacteria that is a challenge to scientists.


Bacteria exist everywhere on earth. I mean in our… each of our intestinal systems, we've got more bacteria than there are people living on earth. So amongst those, there are thousands and thousands of different types, and so we are literally swimming in bacteria all the time. It’s a very small proportion of these that actually cause disease – most of them are beneficial to us. Indeed, life on earth as we know it would stop without all these organisms. So when you are trying to identify specific organisms, you are really looking at one or two amongst a whole background of other organisms, and they are very good at adapting, so they will change their system so they are able to live in new hosts and adapt to new conditions. So there is a constantly changing bacterial population going on, so when we go to look at our faecal source identification tools, we've got to really sift through a wide range of bacteria, some of which will only be transiently present, some which are present in very low levels, and others which may be present in a whole range of organisms, some which may not be present in faecal material, some which may grow in the environment and be found in other places. So for faecal source discrimination, you've really got to find just those bacteria or other organisms which are only present in faeces and, ideally, only present in a particular animal source.