Today’s ASM News Digest reported that on 04 April, Thomas D. (Tom) Brock passed away at the age of 94 (Microbiologist Thomas Brock Dies at 94 | The Scientist Magazine® (the-scientist.com). This week there was also a column about him in the New York Times (Thomas Brock, Whose Discovery Paved the Way for PCR Tests, Dies at 94 – The New York Times (nytimes.com)). Here I’ll share my personal story.
Although Tom spent most of his career as a professor at the University of Wisconsin-Madison, I had the great fortune of having been one of his students during his tenure (1960 to 1971) at Indiana University (IU). By the first semester of my senior year at IU, I had completed all of my required course work but still needed 12 credits to graduate. At that time, one of Tom’s graduate students was developing radiotracer methods for investigating the ecology of microbes that grew on rock and plant surfaces (the term biofilm had yet to be coined). In late 1969, I approached Tom and asked if he would support having me work in his lab and earn my remaining credits performing a research project. Tom agreed, took me under wing and assigned me lab space where I would be working alongside his team of graduate students.
To report that working as one of Tom’s disciples during my last semester at IU was a foundational experience would be an understatement. I had decided that I wanted to become a marine microbiologist and had developed a keen interest in the ecology of extremophiles (microbes that thrived in extreme environments such as deep ocean thermal vents, under and within polar ice, and at high – > 200 atmospheres – pressures). After learning about the vast network of underground rivers that flowed through Southern Indiana and being advised by a geology professor that the underground river temperatures remained a constant 10 °C (50 °F) throughout the year, I hypothesized that these rivers might be habitats for obligate psychrophiles (microbes that grew optimally at temperatures £20 °C – £68 °F). Tom encouraged me to take up spelunking and to use a nearby underground rivers as my field sites. I set up arrays of microscope slide coverslips midstream in several cave rivers, then recovered coverslips every few hours for the next several days. I then ran a battery of tests on the recovered coverslips. The first thing I learned was that the coverslip populations reached a dynamic steady state within 24h. The next thing I learned was that, based on both radiotracer and culture testing, the populations preferred life at 25 °C to 30 °C. My work resulted in a publication (Absence of Obligately Psychrophilic Bacteria in Constantly Cold Springs Associated with Caves in Southern Indiana on JSTOR) – making 2020 the 50th anniversary of my first published research work.
Beyond the mechanics of various laboratory methods, Tom taught me that in the world of microbial ecology, hypothesis were tools for helping one to think about a topic and to design a test plan. Hypotheses should not become theories to be proved. In the half-century since I learned in Tom’s lab, I’ve encountered too many instances in which researchers became fixated on their hypotheses and took measures to ensure that their data supported those hypotheses. I can also attribute my general distrust of culture test data to Professor Brock. Having pioneered a number of non-culture methods, he advised against over-reliance on the stories told by the relatively few microbes that we knew how to culture (see FUEL & FUEL SYSTEM MICROBIOLOGY PART 3 – TESTING – Biodeterioration Control Associations, Inc. (biodeterioration-control.com)). In addition to my primary research, I had an opportunity to dabble in acid mine drainage stream microbiology. Populations of acid-loving (acidophiles) thrived in pH 2 (essentially, concentrated sulfuric acid) streams – talk about extreme environments!
While I was under his wing, Tom published the first edition of Biology of Microorganisms (the 15th edition was published in 2018). When the book was published, Tom offered his ducklings $1 per error we found. Each of us made out quite well in several respects. Biology of Microorganisms was the first microbiology textbook that presented the topic from a microbial ecology, rather than clinical microbiology, perspective. We each received a few dollars by detecting errors. Our close, critical reading of the text and inspection of each figure was educationally rewarding. As an undergraduate, the experience taught me that regardless of how many times a paper is reviewed, errors are likely to slip by, undetected. Later in my career, I formulated this lesson into a meme: even after you have 100 people review a manuscript, the 101st reviewer will catch errors everyone else has missed.
Culminating the tremendous mentorship Tom provided, I’m convinced that his recommendation paved the way for my successful application to graduate school. In 1988, Professor Brock received the American Society of Microbiology’s Carski Award for Undergraduate Education. Writing one of the letters in support of his nomination to receive the gave me an opportunity to repay his kindness in a small way. Despite having had many great teachers over the years, I still refer to myself as a Brock acolyte. The lessons I learned from Tom inform me to this day. He was one of microbial ecology’s great pioneers.