The Curious World of Bacteria

Bacteria might well be some of the most underappreciated lifeforms on our planet. With this book, former microbiologist and current science communicator Ludger Wess introduces fifty different bacteria to show how they are much, much more than just pathogens. With short, bite-sized chapters, this is a popular science introduction to microbiology that you can dip into at any time.

This book was originally published in German in 2020 as Winzig, zäh und zahlreich: ein Bakterienatlas by Matthes & Seitz and has been translated into English by Jamie McIntosh. The book combines a 40-page introductory essay with fifty species portraits, grouped into six sections. Each chapter is very short, the majority running 3–4 pages only. As a popular-science introduction to microbiology, it sounds like an interesting and quite formidable writing challenge. But do fifty bacterial appetizers a satisfying meal make? Though I was initially somewhat sceptical, and the chosen format has its limitations, Wess covers many different facets of what makes microbiology interesting and relevant.

One thing I particularly liked is that he addresses so much more than just the pathogen angle, describing the role of bacteria in the metabolic and energy cycles of organisms and ecosystems. I thought the introduction was particularly informative. For example, few people outside microbiology will know how we discover and study bacteria today. Rather than isolate and culture individual species, researchers analyse all the genetic material found in e.g. a sample of soil to try and reconstruct the many different organisms living in it. This is the field of metagenomics and is a quick-and-dirty method to get to grips with the billions of still unknown species out there, though the unavoidable downside is thinking of an organism only in terms of its genetic sequence. Wess also discusses some of the unusual things bacteria can do. I was pleased to find mention of relevant topics such as horizontal gene transfer (the exchange of genetic material within, rather than between, generations that can readily cross very wide species boundaries) and the recent discovery of the bacterial immune system known as CRISPR that has been turned into a biotechnological tool that has taken the world by storm. Wess is particularly interested in extremophiles, the proverbial microbes from hell that can survive and often need extremes of temperature, acidity, or pressure. As he shows, this has a direct bearing on understanding the origins of life and on astrobiology: the study of life elsewhere in the universe. One of the most eye-opening facts is that bacteria live deep inside the planet in pores in the rock, making a living off minerals and radioactivity. Wess reminded me why I really, absolutely must make time to finally read Deep Life.

With this broad introduction as a basis, the majority of the book consists of the species profiles. Usefully, Wess has grouped his examples into six sections. This obviously includes pathogens but also useful bacteria: those fermenting food, leeching metals out of crushed rock, or producing fuel (alcohol) from exhaust fumes such as carbon dioxide and carbon monoxide.

The stars of the show are the far more exotic organisms. Record holders such as the largest and smallest bacteria reveal much about how life operates at its limits. Pelagibacter ubique might be the smallest known independent living bacterium, but it is so numerous that it makes up one-quarter to, at times, one-half of the ocean’s bacterial biomass and influences the planetary carbon cycle by decomposing other organisms. Fourteen fascinating extremophiles allow Wess to describe the biochemical and cellular details by which bacteria survive scorching temperatures, acidic mining waste, the crushing pressure of the deep ocean, or the bone-dry conditions in Antarctica. There is great interest in these from chemical industries hoping to harness bacteria to clean up toxic waste. Many bacteria have already made their home amidst our technological infrastructure, living inside nuclear reactors, snacking on plastic, or living in what we hoped were sterile environments such as distilled water or clean rooms used to assemble spacecraft. Some of the most fascinating ones were the four species grouped as exotic eaters that live off metals, including Ralstonia syzygii which metabolizes the silicon wafers that go into electronic chips.

The fragmentary nature of so many short chapters does, understandably, get in the way of telling a larger narrative. Even so, reading between the lines, I noticed two welcome trends. First, there is the undercurrent of a pro-chemistry attitude. We tend to think of hydrocarbons and dioxins purely in terms of toxic pollutants, but bacteria have been thriving for millions of years on naturally occurring tar and oil seeps while dioxins are generated in volcanic eruptions, forest fires, and geothermal processes, and are used by a wide variety of organisms. Bacteria force you to reexamine your ideas of "natural" and "unnatural". When it comes to chemistry, there are few things that bacteria cannot already do better than us. The second trend, neatly balancing the first, is that Wess is no techno-optimist. Sure, he writes of bioremediation, the use of bacteria to clean up pollution such as oil spills; and of engineering applications such as self-healing concrete that uses bacteria to grow lime into the cracks of ageing structures. But he is always cautious in his optimism and quick to outline hurdles and limitations.

Each species profile is illustrated with a drawing by Falk Nordmann. Having looked at his website, he makes beautiful illustrations, but a brief that reads "draw 50 different spheres and rods" will challenge anyone. It is a shame they are reproduced as small, greyscale versions in each chapter heading: the colour versions on the cover and the large drawings on the title page show the effort and character that have gone into each.

In the end, I was pleasantly surprised by this book. The format has its limitations, but Wess convincingly shows why bacteria are relevant and fascinating. This is a book you can dip into at will, making it great if you are hard-pressed for time or want something to read on a short commute. Even if you have only a few minutes to spare, you can readily start and finish a chapter.