Tay mud. You remember the stuff - thick, evil smelling gunk the colour of Bovril and the consistency of uncooked chocolate cake without the finger-lickin' appeal. Its shifty habits make the Firth of Tay fascinating to those viewing it from the air, frightening to those trying to navigate its waters and foul to anyone foolish enough to get stuck in it.
Yet it was this same mud that effectively moulded the career of one successful graduate. George Macfarlane graduated in microbiology in 1980 but became particularly familiar with mud when researching the ecology of the Tay Estuary for a PhD with the department of biological sciences. It was the knowledge he gleaned of the habits of mud loving organisms - sulphur bacteria- that, in his later Cambridge years, would inspire a "eureka moment" in his research into quite a different area - the gut. Last year George and his Dundee graduate wife, Sandra, returned to their native city with a team of scientists to pursue research into the microflora of the gut.
But let's go back to the mud. The source of the inspiration was bacteria which thrive in the oxygen-free sediments gobbling up hydrogen from fermenting microbes in the stagnant mud and sulphate from sea water. From these the bugs make their own energy and in the process produce a poisonous waste gas, hydrogen sulphide, with its telltale smell of rotten eggs.
Much later when looking at bacteria in the intestine and how they affect health and disease, George would remember the mud bugs and ask, could these also be living in the lower gut of some people? After all, meat and junk food with its sulphur preservatives, are heavy in sulphur compounds. Since then the evidence has followed implicating sulphur bacteria in a range of diseases from inflammatory bowel conditions to colon cancer.
But not all gut bacteria are "baddies". Many help us digest food, trigger the immune system and provide a vital barrier to infection. It is a topic on which George can wax lyrical.
"It's a fascinating area. The gut is not just a simple tube, it has its own microflora - a huge population of bacteria of which we know very little. At present we can only identify about 20 per cent. The gut and its bacteria effectively act as an enormous metabolic organ - like the liver or the kidneys - which has evolved over millions of years."
He warms to his topic: "There are about 200 grams weight of bacteria in the bowel - that's almost the weight of a pack of butter - with some 10 to the power of 12 bacteria per gram. When you think that it only takes about 100 E coli 0157 to kill you, you realise the extraordinary power of this ecosystem."
Now George and his team are looking for answers to questions such as "Why do gut bacteria attack some cells and not others? How do they recognise and digest food particles as distinct from host tissue?"
"If you think about it, it's quite odd that they don't simply digest the host itself - and of course some forms of bacteria do, so there's this perpetual race going on in the system between the host regenerating tissue and bacteria eating away at it. But somehow this is kept in balance. When that balance is upset - for example after a course of antibiotics - there can be problems. The young and the old are more susceptible to bowel disease possibly because their guts are not so well colonised by bacteria and this is an area we are looking at."
For George the return to Dundee and the newly enlarged department of molecular and cellular pathology is a tremendously positive move.
"Dundee - and this department - is really going somewhere. When we went to Cambridge 15 years ago I said I would never come back but I never envisaged such changes. Things are really happening here and I never appreciated the great quality of life Dundee has to offer."
His wife Sandra who graduated in 1982 in microbiology, is also glad to be back. The couple married while undergradutes at Dundee. Now employed by the Medical Research Council she is part of the same group of ten who have moved to the city with £1.8 million of MRC research grants. They hope others will cotton on to what Dundee has to offer matching quality of life and excellence in the field. "We hope they'll follow...but not too many!"
