The polar microbiologist, David "Wynn" Wynn-Williams, who has died aged 55 in a traffic accident while jogging near his home in Cambridgeshire, was a man who cared passionately about his science and the Antarctic environment. In recent years, he had broadened his enthusiasms, from studies of life at polar limits to considerations of life on other planets in the fledgling field of astrobiology.
Born in West Kirby, on the Wirral peninsula, he attended Calday Grange grammar school and Birkenhead technical college, before moving to the University College of Wales, Aberstwyth, to read botany and microbiology for his first degree, and marine microbiology for his PhD.
Aberstwyth was an obvious choice for David, with his Welsh ancestry and love of all things Welsh. His father had imbued him with a love of rugby and male voice choirs and, while his rugby career was shortlived, his passion for choral singing - in a very capable bass voice - brought memorable experiences, including involvement in the choir at the investiture of the Prince of Wales, and acting as the narrator to a performance of Vaughn-Williams' Antarctic Symphony in Cambridge some 30 years later.
His research on the ecology of nitrogen-fixing marine bacteria provided the first evidence of his abilities to operate under exacting conditions and to improvise equipment and techniques. His enthusiasm made him a natural choice to lead a research expedition to Iceland in 1970, an ideal lead into his subsequent Antarctic work.
After teaching for a couple of years in south London and Tonbridge, Kent, in 1974 he joined the British Antarctic Survey (Bas) as a soil microbiologist, spending two winters at Signy Island, in the maritime Antarctic, where he made the first detailed study of Antarctic microbial populations in relation to carbon respiration.
David's abiding passion for polar regions, and his deep appreciation of the Antarctic environment, were firmly established during his time on Signy Island. New research opportunities abounded, though working conditions were then often very primitive. To ensure that our microorganisms did not experience temperatures above that of their natural environment, the laboratory he and I occupied for two years was entirely unheated. An air hole in the floor ensured that bench temperatures were 2C, while below bench level was permanently sub-zero.
David threw himself into all elements of polar life, with its traditions and unique camaraderie as well as its numerous privations. He adored adventure - scuba-diving with seals under the ice, or scaling ice-covered mountain ridges; photography and the history of Antarctic exploration - particularly of the whaling origins of Signy Island - were also passions. Only someone with David's persistence could have tracked down Signe Sorlle, after whom Signy Island was named by her whaling captain husband in 1912; David's picture of Signe, at home in Norway, still hangs in Signy Base.
After his return to Britain in 1977, David was soon offered a permanent post at Bas, leading soil microbiology research. This provided a springboard to make 10 further summer visits to Antarctica, with colleagues from New Zealand, America and Italy.
Having initially studied how freeze/thaw events controlled microbial respiration processes, his research led him to believe that moisture - not temperature - was the key controlling factor in these extreme environments. His work was recognised with the award of a Polar Medal in 1980 for outstanding contributions to Antarctic research.
David became increasingly fascinated with the structure of microbial communities, and developed image analysis approaches that allowed him to visualise the three-dimensional structure of soil microbial communities, and to study the patterns of colonisation in these harsh environments. He subsequently used colonisation of Antarctica as a central element of an international research programme on terrestrial polar ecosystems (Biotas), of which he was a dynamic co-organiser.
During the 1990s, after he became head of terrestrial ecology at Bas, he found himself promoting Antarctica and its micro-organisms as analogues for extraterrestial life and wrote a number of important reviews on ultra-violet (UV) radiation and its biological consequence.
David began studying the development of UV-protective pigments in Antarctic cyanobacteria under the ozone hole, and identified that these long-lived biomolecules could provide biomarkers for life in extreme environments on earth and on other planetary bodies. In due course, an Antarctic Astrobiology Group was created around him at Bas, an event that coincided with, arguably, his most productive period of scientific activity.
He worked with Nasa Ames Research Centre, the Nasa Johnson Space Centre and the European Space Agency to put experiments or instruments into space. His legendary networking abilities and enthusiasm helped establish a British astrobiology network, in promoting and developing astrobiology worldwide and, most recently, in the creation of an International Journal of Astrobiology.
David's involvement with the Raman spectroscopy group at Bradford University was yielding a steady stream of significant papers on biomolecule identification, while his polar background made important contributions to the debate on the possibility of water and life on Mars, and the origins of life. At the time of his death, he was at the height of his research powers.
Apart from his dedication to science, he was an enthusiastic participant in several London marathons and a member of Cambridge choral societies. His is survived by his wife, Elizabeth, and his two teenage daughters.
David Donaldson Wynn-Williams, microbiologist and astrobiologist, born July 16 1946; died March 24 2002