Alfred Pühler

Forty years (and counting) at the forefront of microbiology research have not dimmed Pühler's infectious enthusiasm or voracious work ethic.

By Cormac Sheridan

Alfred Pühler has been a powerhouse in German microbiological research—initially in the area of plant-microbe interactions and later in industrial microbiology—over the past four decades. But he actually started out in nuclear physics, obtaining his first degree in that discipline from the University of Erlangen (now the University of Erlangen-Nuremberg) in his native Bavaria in 1967. Around the same time, however, his attention was pulled in a completely different direction. "I watched two television programs dealing with the discovery of the genetic code," he recalls. The informational aspects of biology implicit in that work intrigued the young physicist.

Without ever studying biology, he embarked on a PhD in microbiology at the Institute of Microbiology at Erlangen where he became one of the early pioneers of...

Recently retired from his faculty position at the University of Bielefeld in North Rhine-Westphalia, he currently holds a research professorship and is executive director of the Center for Biotechnology (CeBiTec), an interdisciplinary life sciences institute at the university. He is recognized throughout Germany's wider scientific community as an elder statesman. In 2008, he became foreign secretary of the Union of German State Academies of Science and Humanities; he previously served as the only biologist on the German Council of Science and Humanities, a high-ranking advisory body on research to both federal and state governments.

Pühler has been both a witness to and an active participant in the massive transformation of microbiology in recent decades, enabled by the development of new techniques for probing the inner workings of bacteria. At a methodological level, working with Reinhard Simon, his most noteworthy contribution was the development of a transposon mutagenesis system for the site-specific insertion of foreign genes into the genomes of Gram negative bacteria. "The technology is used worldwide," says Pühler. The paper describing the technique has been cited more than 3,000 times (BioTechnol, 1:784–91, 1983).

"We were one of the first labs in Germany to do genetic engineering."

These days, he is an enthusiastic proponent of ultra-fast genome sequencing, using the pyrosequencing method. Pühler's group was part of a consortium that published the genome sequence of the nitrogen-fixing symbiotic bacterium Sinorhizobium meliloti back in 2001 (Science, 293:668–72, 2001). That multinational effort cost €5 million and took several years. "Now we can think about [doing 80 strains] in two or three years," says Pühler. "Our plan is to sequence all 80 type strains of Corynebacterium." The goal is to develop an understanding of the comparative genomics of Corynebacteria species, which are of both medical and industrial importance.

Pühler sees sequencing as the starting point rather than the end game in any biological investigation. "You can design much better experiments if you have the genome sequence in the background," he says. "You know the lifestyle." Pühler's group has taken a particular interest in the metagenomics and the metatranscriptomics of anaerobic bacterial communities found in biogas fermenters. CeBiTec is currently establishing a consortium with the local gas and power utilities in Bielefeld to build a full-scale production plant in order to investigate the effects of feedstock changes on the microbial composition of biogas fermentation systems. The goal here is to develop bacterial inocula that are optimized for different feedstocks, and thereby eliminate the lag associated with a change of feedstock material.

Pühler's group also remains a central player in the ongoing effort to understand the complex biology of nitrogen fixation. It performed the first, and up to now, the only deliberate release in Germany of a genetically modified bacterium, a luciferase-tagged strain of S. meliloti. However, Germany's—and Europe's—disavowal of biotechnology in agriculture remains "a huge disappointment".

The research continues, however, according to the work ethic Pühler established early in his career. "It was very clear that we worked on Saturday; I still work on Saturday." It continues along the intellectual pathway he started on as a young man. "I've followed this line up to now," He says. And from the looks of it, he is still far from finishing.

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