Some might claim that there is nothing new under the sun, but a scientist from NUI Galway is happy to prove them wrong day after day. He has discovered members of a new form of life living literally right on our doorstep.
Dr Richard Powell lectures in the department of microbiology in Galway and is an expert in this new life-form, the archaea. Yet while their existence was only discovered in the late 1970s, the archaea were likely among the first organisms to begin colonising the earth three billion years ago.
The scientific community was turned on its head in the late 1970s when Dr Carl Woese and colleagues at the University of Illinois used DNA sequences to study the kinships between bacterial forms. Originally thought to be more or less the same, he discovered that they divided into two different groups.
Because of the huge difference in genetic make-up, he proposed that the popular way at the time to subdivide life, the Five Kingdoms, including four eukaryotic kingdoms (plants, animals, fungi and proists) and one prokaryotic kingdom (the bacteria), be jettisoned.
His alternative called for three domains, the eukaryota, which includes us, the eubacteria, including all bacteria, and the new group, archaebacteria, later shortened to the archaea.
The archaea were the celebrity bugs originally discovered living in the most inhospitable places on earth. They were recovered from thermal vents at the ocean floor living in water hot enough to boil. They lived in chemical-laden marshes where the salt levels killed off most other life.
"We only have 150 cultured species of these, and they all come from what are termed 'extreme environments'," Dr Powell explains. This led scientists wrongly to assume that all archaea were "exteremophiles". "I work in what is called the molecular ecology of bacteria using DNA to study bacteria in the environment," he says. He decided to look for archaea in other places and in less extreme conditions.
What he discovered was also a surprise. "Archaea are ubiquitous in the environment," he says. "If you go out to try to culture them, you find them everywhere." The modern forms are distantly related to their extreme cousins, but only a small number of the total appear to be extremophiles.
These discoveries could not be made without the use of genetic analysis because it is notoriously difficult to culture wild bacteria, he says. A given water or soil sample is usually teeming with life of all sorts, not just one convenient species. If the sample is cultured, then one quick grower will usually take over, crowding out the others and taking full control of the petri dish. "Some adapt to the conditions much more effectively than others."
Dr Powell finds the archaea by using a completely different sampling method, by analysing the DNA contained in a bug's ribosomes. A ribosome is an essential cell component that enables the instructions packed into DNA to be translated into proteins. This multi-step process depends on ribosomes, and all species in the three kingdoms - including humans - have ribosomes.
"Because the bacteria won't grow for us in the laboratory, we collect water samples, filter off the cells and isolate for certain ribosomal genes, and we can compare them," Dr Powell says. Once this DNA is found, it is sequenced and examined for mutations, the small changes that occurred over millions of years that caused separate species to evolve.
The researchers at Galway, including five post-doctoral students, catalogue the mutations, which provide an evolutionary roadmap that allows the researchers to read forward or backward on the procession of species. "The greater the number of mutations there are, the more distantly related you are. It changes some of our views of evolution."
It suggests that the early bacteria were probably not dining comfortably on the "primordial soup" proposed by Darwin. The early Earth was hot and chemically poisoned, which meant the "first bacteria were in fact quite complicated, they had quite complex metabolic characteristics" enabling them to survive.
Dr Powell now finds archaea just about everywhere, and suggests that they may in fact be more plentiful than bacteria. "There are whole new phyla out there that haven't been cultured," he believes.
His research is funded by a grant from Enterprise Ireland and by the university's Millennium Fund.
The RIA Award in Microbiology has been given annually since 1995 in recognition of quality research. Only persons who are younger than 40 years on January 1st in the year of the award are eligible, so it celebrates the work of our younger scientists.