How a Czech Scientist Mastered Continuous Culture
In the world of science, true revolutionaries don't just answer questions—they change how we ask them. Professor Ivan Málek was such a revolutionary. This Czech scientist saw microorganisms not merely as germs to be eliminated, but as microscopic factories, environmental cleaners, and medical allies waiting to be understood. His vision gave birth to the Institute of Microbiology of the Czech Academy of Sciences (CAS) in 1962, which has since grown into the largest institution in the Czech Republic dedicated to studying microorganisms for applications in medicine, industry, and environmental protection1 5 .
What makes Málek's story particularly compelling is that his most important scientific contribution—the development and perfection of the continuous culture of microorganisms—emerged from a simple yet powerful insight: Nature doesn't operate in batches, so why should microbiology?
While researchers worldwide were studying microbes in closed test tubes and flasks where conditions constantly changed, Málek envisioned a system where microbes could be studied in a steady, controlled state that mimicked their natural environments5 . This breakthrough would open doors to unprecedented discoveries in microbiology, biochemistry, and medicine that continue to shape science today.
Ivan Málek's path to scientific prominence began long before the official founding of the institute that would become his legacy. Born in 1909, he graduated from the Faculty of Medicine at Charles University and worked at the Institute of Bacteriology and Serology5 . His career progressed through various positions at the National Institute of Public Health and Fragner's pharmaceutical factory, eventually leading him to become a professor of microbiology and immunology at the Faculty of Medicine of Charles University in Hradec Králové5 .
Málek founded a working group focusing on microbiology at the Faculty of Medicine in Hradec Králové5 .
The working group evolved into the microbiology department at the Central Institute of Biology5 .
The department moved to Prague as the Microbiology Department of the Institute of Biology of the Czechoslovak Academy of Sciences5 .
Málek served as the first director of the newly independent Institute of Microbiology of the Czechoslovak Academy of Sciences5 .
Málek's leadership extended beyond institutional building. He was at the beginning of domestic antibiotic research and was one of the founders of the Research Institute of Antibiotics in Roztoky near Prague5 . His scientific contributions were matched by his ability to inspire and organize, making him among the first important personalities of the Czechoslovak Academy of Sciences.
The Institute of Microbiology found its permanent home in 1963 when it moved to the newly established premises of the biological institutes of the Czechoslovak Academy of Sciences in Prague-Krč1 5 . This location would become the heart of microbiological research in Czechoslovakia, and later the Czech Republic.
Located in Třeboň, focusing on research of microscopic algae, cyanobacteria and photosynthetic bacteria5 .
In Nový Hrádek, specializing in studying the influence of intestinal microflora on immune mechanisms5 .
At Nové Hrady Château in South Bohemia for scientific gatherings5 .
A joint biotechnology and biomedical research center with Charles University in Vestec5 .
Under Málek's leadership and that of subsequent directors, the institute's research scope expanded to encompass cellular and molecular microbiology, genetics and physiology of microorganisms, antibiotic resistance, microbial metabolites, soil ecology, ecotoxicology, and immunology1 . The institute also maintained an internationally recognized collection of basidiomycetes and its own biotechnological unit for monitoring microbiological processes at a semi-operational scale1 .
The continuous culture method, often called a chemostat, works on a simple but elegant principle: by controlling the flow rate of fresh medium into the culture vessel, researchers can precisely control the growth rate of microorganisms and maintain them at a constant concentration5 . The key innovation was the recognition that when the dilution rate (flow rate divided by culture volume) equals the growth rate of the microorganisms, a steady state is achieved where cell density remains constant.
To understand the significance of Málek's contribution, let's examine how a typical continuous culture experiment is conducted, based on the methodologies he developed.
The continuous culture system consists of a culture vessel with sterile medium reservoir, precision pump, effluent collection system, aeration and mixing system, and temperature control5 .
The culture vessel is filled with sterile nutrient solution and inoculated with a pure culture, allowed to grow in batch mode until mid-exponential growth phase5 .
Once sufficient cell density is achieved, the medium pump is started at a predetermined flow rate, allowing the system to reach steady state5 .
Samples are taken from the effluent at regular intervals, measuring cell density, substrate and metabolic product concentrations5 .
The continuous culture method generated quantitative insights that revolutionized our understanding of microbial life. Below are three tables representing the types of data that Málek and his colleagues would have produced and analyzed.
| Dilution Rate (h⁻¹) | Glucose Concentration (g/L) | Cell Density (OD600) | Doubling Time (minutes) |
|---|---|---|---|
| 0.1 | 2.0 | 0.85 | 416 |
| 0.2 | 2.0 | 0.82 | 208 |
| 0.3 | 2.0 | 0.78 | 139 |
| 0.4 | 2.0 | 0.71 | 104 |
| 0.5 | 2.0 | 0.65 | 83 |
| 0.6 | 2.0 | 0.52 | 69 |
| Dilution Rate (h⁻¹) | Ethanol Production (g/L) | CO₂ Evolution (mL/min) |
|---|---|---|
| 0.1 | 0.5 | 15.2 |
| 0.2 | 0.8 | 28.7 |
| 0.3 | 2.5 | 45.3 |
| 0.4 | 4.2 | 52.1 |
| 0.5 | 5.8 | 48.3 |
| Dilution Rate (h⁻¹) | Oxygen Consumption (mmol/L/h) | Glucose Utilization (mmol/L/h) |
|---|---|---|
| 0.1 | 12.5 | 2.1 |
| 0.2 | 24.8 | 4.3 |
| 0.3 | 35.2 | 6.2 |
| 0.4 | 42.7 | 7.9 |
| 0.5 | 48.3 | 9.4 |
These data tables illustrate the power of continuous culture in revealing fundamental relationships between growth rate, metabolism, and nutrient utilization—relationships that were nearly impossible to quantify accurately using batch culture methods.
The development of continuous culture required not just theoretical insight but also practical tools and reagents. The table below outlines essential components of the microbiologist's toolkit, both in Málek's time and today.
| Reagent/Method | Function | Application Example |
|---|---|---|
| Nutrient Broths | Provide essential nutrients for microbial growth | Supporting growth of bacteria in continuous culture studies |
| Antibiotic Sensitivity Discs | Determine effectiveness of antimicrobial agents | Testing new antibiotics discovered from microbial sources |
| Selective Media | Favor growth of specific microorganisms while inhibiting others | Isolating specific bacterial strains from environmental samples |
| Agar Plates | Provide solid surface for microbial colony growth | Purifying microbial cultures and counting colony-forming units |
| Staining Reagents | Enhance visibility of microorganisms under microscopy | Differentiating bacterial types (Gram staining) |
| Buffer Solutions | Maintain stable pH conditions | Ensuring optimal enzyme activity in experimental conditions |
| Enzyme Assays | Measure enzyme activity and kinetics | Studying metabolic pathways in microorganisms |
| PCR Reagents | Amplify specific DNA sequences | Identifying microbial species and genetic modifications |
| Restriction Enzymes | Cut DNA at specific sequences | Genetic engineering of microbial strains |
| Electrophoresis Gels | Separate molecules based on size and charge | Analyzing DNA, RNA, and protein samples |
The Institute of Microbiology of the CAS continues to be a vibrant research institution more than six decades after its founding. With 27 laboratories, approximately 700 employees, and over 160 research projects, the institute remains at the forefront of microbiological science.
Studying the fundamental genetic mechanisms of microbial life5 .
Examining the impact of harmful substances on the environment1 .
Studying the role of microorganisms in immunity and autoimmune diseases1 .
The institute has also been responsible for significant discoveries beyond Málek's continuous culture method, including the discovery of mucidin, the only Czechoslovak antibiotic that entered clinical practice for human and veterinary medicine5 . This discovery by Vladimír Musílek and his colleagues exemplifies the institute's ongoing commitment to translating basic research into practical applications.
Ivan Málek's creation of the continuous culture method represented far more than a technical improvement in laboratory practice—it embodied a fundamental shift in how scientists could interrogate microbial life. By allowing researchers to maintain microorganisms in a stable, controlled state for extended periods, the method opened new windows into microbial physiology, genetics, and metabolism.
The Institute of Microbiology of the CAS stands as a testament to Málek's vision, continuing to build upon his legacy of excellence in microbiological research. From its beginnings as a small working group in Hradec Králové to its current status as the largest institution of its kind in the Czech Republic, the institute has remained committed to Málek's original insight: that understanding microorganisms means understanding some of the most powerful forces shaping our health, our environment, and our industrial capabilities.
As we face new challenges in antibiotic resistance, environmental pollution, and emerging diseases, the approaches pioneered by Málek and refined by generations of scientists at the institute he founded have never been more relevant. The continuous culture method continues to evolve, finding new applications in biotechnology, systems biology, and synthetic biology—proving that truly revolutionary science never stops growing.