How 75 Years of Microbial Physiology Fueled a Revolution
Beneath our notice, microbes orchestrate Earth's most vital processes—from digesting pollutants to brewing antibiotics.
For 75 years, the journal Microbiology has chronicled breakthroughs in understanding these invisible powerhouses. This journey began not with flashy headlines, but with meticulous studies of how microbes grow, breathe, and compete. By unraveling their physiological secrets, scientists unlocked tools to fight disease, clean the environment, and harness microbial potential 4 5 .
Before the 1950s, microbes were grown in batch cultures—a start-stop method limiting precise physiological study. In 1956, Herbert, Elsworth, and Telling pioneered the chemostat, a device that feeds nutrients continuously into a microbial culture. This allowed unprecedented control over growth rates, revealing how bacteria balance energy use and division under nutrient scarcity 4 .
Microbes face a dilemma: oxygen fuels energy production but generates toxic radicals. The discovery of FNR, an oxygen-sensing protein in E. coli, revealed how bacteria switch between aerobic and anaerobic metabolism. Mutants lacking FNR (fnr genes) couldn't grow without oxygen, exposing a master regulator of respiration 4 .
Iron, copper, and zinc are essential yet deadly in excess. Seminal work showed:
Calculate how efficiently microbes convert food into biomass.
Unified microbial bioenergetics, enabling metabolic engineering (e.g., antibiotic overproduction in Streptomyces) 1 .
YATP = 10.5 grams of cells per mole of ATP.
Proved energy conservation applies across microbes, predicting growth from metabolic pathways.
| Parameter | Batch Culture | Continuous Culture (Chemostat) |
|---|---|---|
| Growth Rate | Uncontrolled | Precisely adjustable |
| Nutrient Availability | Depletes over time | Constant replenishment |
| Study Applications | Basic screening | Infection models, industry |
| Microbe | Energy Source | YATP (g cells/mol ATP) |
|---|---|---|
| Enterococcus faecalis | Glucose | 10.5 |
| Saccharomyces cerevisiae | Ethanol | ~6.0 |
| Clostridium acetobutylicum | Starch | ~8.2 |
Essential reagents and tools from landmark studies:
| Tool/Reagent | Function | Example Use |
|---|---|---|
| Chemostat | Maintains steady-state microbial growth | Quantifying nutrient requirements |
| Green Fluorescent Protein (yEGFP) | Tags proteins in live cells | Tracking stress responses in fungi |
| CDCL Toxins | Pore-forming bacterial "weapons" | Targeting cancer cells (repurposed) |
| Fe³âº-Pyoverdine | Iron-scavenging siderophore | Studying pathogen nutrition in hosts |
| FNR Mutants | Disrupt oxygen sensing | Probing anaerobic survival mechanisms |
From chemostats to cancer-fighting toxins, 75 years of microbial physiology research transformed our grasp of life's smallest architects. Today, this legacy fuels synthetic biology, climate-resilient crops, and engineered probiotics 2 . As Microbiology shifts to open access, its foundational insights remain a beacon—proving that understanding how microbes grow, breathe, and battle is key to harnessing their power for humanity's next challenges 5 .
"Microbes are the chemists of survival; their physiology writes the recipes of life."