Are Microbes the Future of Bioenergy? – Interview with Gerhard Gottschalk

Recently the German National Academy of Sciences, Leopoldina, published the comprehensive analysis Bioenergy – Chances and Limits on the use of bioenergy. The report is critical of the current alternative fuels policies of the EU and national governments and generated a great deal of interest among the press.

Professor Gerhard Gottschalk, Georg-August University, Göttingen, Germany, a leader in the field of microbiology talks to Drs. Vera Köster and Gregor Cicchetti for ChemViews magazine about the report and bacteria’s role in the future of bioenergy.

What do you think of the report from Leopoldina?

This is a benchmark review which hopefully will not simply be glanced at, but studied, by decision makers, lobbyists, scientists, and the interested public. Its advantage is that it consists of two parts, a scientific review (published in English), extremely beneficial to those readers who have a background in science, and an executive summary part with recommendations written in German and English.

The overall result may be disillusioning for those who proclaim that our future lies primarily in bioenergy. In the long run it will not be possible to produce biogas and biofuels in the amounts required to provide more than 10 % of our energy demands.

The three chapters cover the availability and sustainability of biomass as an energy source, the conversion of biomass into biofuels, and solar driven hydrogen generation from water. If the technical problems can be solved, the latter technology may become the technology of the future to provide energy for transportation, for the provision of electricity, etc. The most critical chapter is the first one, because here, the limitations of bioenergy generation are discussed. It states “that with the exception of the use of biogenic waste, the large scale use of biomass as energy source is not a real option for countries like Germany”.

The statement was compiled by a working group of more than 20 expert scientists coordinated by Professors Bärbel Friedrich, Humboldt-Universität Berlin, Bernhard Schink, University of Constance, and Rudolf K. Thauer, Max Planck Institute for Terrestrial Microbiology, Marburg. They also wrote statements for your books “Welt der Bakterien” and “Discover the World of Microbes”.

How are your books related to the topic of bioenergy?

I collaborated with all three of them, especially in the area of microbial genomics and there are a couple of statements of these colleagues in my books.

Of course, I covered bioenergy in my books, in chapters 13 and 15 of the German edition and chapters 16 and 17 of the English edition. I was also rather pessimistic and wrote regarding biogas: “Bioenergy villages have been developed, but there are certain limitations. Bioenergy cities are an illusion because biomass collection and transportation would simply use too much energy in the form of vehicle fuels”. I also wrote: “Ethanol, butanol, and biogas – these will be the major products of the fermentation industry in the future, but it still will be difficult to meet more than 10 % of global fuel needs with this type of bioenergy.”

You are one of the most prominent and experienced microbiologists, how do you see future energy production connected to microbes?

Biogas production from waste materials needs further development. We need better enzymes, most likely from microbes, to hydrolyze cellulose and other polymers. Furthermore, the production of butanol or ethanol from syngas (CO + H₂) will become a hot topic. Microbial stars here are organisms such as Clostridium ljungdahlii.

Biofuel from algae is seen as the solution to producing as much biofuel as possible in the smallest amount of space, using the least amount of resources. Do you think this is where the future is heading?

If economically feasible, biofuel production with algae would be great, the big advantage being that we save our soils from massive exploitation. But a breakeven point in terms of economy is far away. Production of high value products by algae is a different story. I’ll just mention β-carotene production by the salt-loving alga Dunaliella at a plant in Eilat, Israel, as an example.

What do you think is the role of microbiology in the 21st century?

The microbial community will have surprises for us, also in the future. New pathogenic bacteria will emerge. We will have to fight the known bacteria and the new ones, as well as the occurrence and spread of microbial resistances to all sorts of antibiotics. Exceedingly dangerous microbes are already around, organisms such as MRSA, multi resistant Staphylococcus aureus.

We also will see new microbial production processes in biotechnology, not only for pharmaceuticals, but also for bulk chemicals, for example, isoprene produced with microbes is just on the horizon.

My concern is the unpredictability of the activity of the huge microbial biomass on our planet as a consequence of the increase in the world population, the exploitation of resources for food and energy production, and the constantly increasing pollution of the atmosphere, the oceans, the rivers, lakes, and soils. Slowly, this biomass will convert overfertilized soils into sand and coast shelves into stinking areas. In this regard, I may mention the experiences with Biosphere 2, a small replica of the earth built in Arizona, USA. This little earth with eight people living in it had to be discontinued after only two years for a number of reasons, one being that enormous microbial activity developed, associated with high CO₂ production, evolution of dinitrogen oxide, and significant oxygen consumption.

What gave you the idea to write a book on the entire scope of bacteria?

About 30 years ago, I wrote a textbook entitled “Bacterial Metabolism”, and I am still pondering whether to update the successful second edition published in 1986. After retirement, I thought I should do something to bring microbes to the attention of interested laymen. So I started writing, actually without having a concept for a whole book. Chapter after chapter developed. Finally I wrote 30 chapters. The result is a book which, I believe, is easy to read and entertaining, but at the same time it imparts to the reader a comprehensive view on microbes.

There is an English and a German edition of the book, the English being much more voluminous. What is the difference between the two?

The English edition contains two more chapters, one on photosynthesis and one on viruses. Furthermore, a study guide was added so that this book may be used as an introductory text.

You are a chemist by training. How did you get interested in microbiology?

I escaped from East Berlin to West Berlin in 1960, so one year before the Berlin Wall was built. After a couple of not very successful interviews, I met Hans-Günter Schlegel who just had accepted the chair of Microbiology at the University of Göttingen, Germany. He was extremely enthusiastic about microbes, and soon I shared this enthusiasm with him. So I got my Ph.D. in Microbiology in Göttingen and afterwards made another move which turned out to become extremely important for me. I went to Berkeley, USA, to become a postdoctoral fellow for Horace Albert Barker who was one of the most impressive and fascinating scientists I ever met.

These two scientists made me a devoted microbiologist. I did not forget my chemistry, but my heart is with the microbes.

What fascinates you most about bacteria?

What fascinates me is that bacteria are extremely small, but incredibly active. By the way, this is the title of chapter 1 of my book. And they are so numerous! 5×10³⁰ microbial cells live on our planet, representing a biomass 100 x larger than the biomass of all animals, including elephants. These microbes are active everywhere, and the sum of their metabolic activity rules our planet.

Do you have a favorite ‘pet’ bacterium?

I may mention that I worked with many microbial species, from methane producing microbes to those making butanol or growing on isopropyl benzene, or those that are unpleasant relatives of Escherichia coli. And I like them all.

Thank you very much for this interview.

Gerhard Gottschalk studied chemistry at Humboldt University, Berlin, then East-Germany, gaining his Diploma in 1959. He then moved to Georg-August University, Göttingen, then West-Germany, where he gained his Ph.D. in microbiology in 1963. From 1964–1966, he was a Postdoctoral Fellow with Professor Horace A. Barker at the University of California, Berkeley, USA. In 1970, Gottschalk became Professor of Microbiology at Georg-August University, where he remained until his retirement in 2003. He remains an active researcher, holding the position of Professor of Genome Research at the same university since his retirement.

From 1998–2000, Gottschalk served as President of the Academy of Sciences, Göttingen, and President of ALLEA (All European Academies) and from 2003–2007 as President of the Union of the German Academies of Sciences and Humanities.

Gottschalk’s current research centers on bacterial metabolism and using genomics to look at the physiology and biochemistry of a certain bacterial species. He has sequenced and analyzed a number of microbial genomes in order to learn about the number of open reading frames (ORFs) present and the possible function of the genes.

Selected Awards

Emil-von-Behring-Preis, 2006
together with W. Goebel
Order of Merit of the Federal Republic of Germany, 1st Class, 2005
Philip-Morris-Award for Technologies of the Future, 1992
together with A. Steinbüchel and H. G. Schlegel

Selected Publications

An ancient pathway combining carbon dioxide fixation with the generation and utilization of a sodium ion gradient for ATP synthesis,
A. Poehlein, S. Schmidt, A.-C. Kaster, M. Goenrich, J. Vollmers, A. Thürmer, J. Bertsch, K. Schuchmann, B. Voigt, M. Hecker, R. Daniel, R. K. Thauer, G. Gottschalk, V. Müller,
PLoS One 2012, 7(3), e33439.
DOI: 10.1371/journal.pone.0033439
The complete genome sequence of Propionibacterium acnes, a commensal of human skin,
H. Brüggemann, A. Henne, F. Hoster, H. Liesegang, A. Wiezer, A. Strittmatter, S. Hujer, P. Dürre, G. Gottschalk,
Science 2004, 305(5684), 671–673.
DOI: 10.1126/science.1100330
The genome sequence of Clostridium tetani, the causative agent of tetanus disease,
H. Brüggemann, S. Bäumer, W. F. Fricke, A. Wiezer, H. Liesegang, I. Decker, C. Herzberg, R. Martinez-Arias, R. Merkl, A. Henne, G. Gottschalk,
Proc. Natl. Acad. Sci. U.S.A. 2003, 100(3), 1316–1321.
DOI: 10.1073/pnas.0335853100