Related Experiment Video
Updated: Jul 3, 2026
08:13
A Novel Bioreactor for High Density Cultivation of Diverse Microbial Communities
Published on: December 25, 2015
Self-cycling fermentation in a stirred tank reactor
1Department of Chemical Engineering, McGill University, Montreal, Quebec, Canada.
Biotechnology and Bioengineering
|November 20, 1993
Summary
Self-cycling fermentations using Bacillus subtilis and Acinetobacter calcoaceticus demonstrated high stability. Stirred tank reactors enabled precise control, facilitating efficient surfactin production without extending cycle times.
Area of Science:
- Biotechnology
- Microbial Fermentation
Background:
- Self-cycling fermentations (SCFs) offer a continuous processing approach.
- Optimizing control parameters is crucial for stable and efficient microbial product generation.
Purpose of the Study:
- To evaluate the stability and control of self-cycling fermentations (SCFs) in a stirred tank reactor (STR).
- To assess the production of surfactin by Bacillus subtilis within the SCF system.
Main Methods:
- Conducted SCFs using Bacillus subtilis and Acinetobacter calcoaceticus in a stirred tank apparatus.
- Monitored dissolved oxygen (DO) and effluent gas analyzer data for process control and harvesting triggers.
- Compared STR performance to cyclone columns for volume control.
Main Results:
- SCFs in STRs exhibited high stability with minimal variation in biomass and doubling time across cycles.
- Surfactin production by B. subtilis was achieved without extending fermentation cycle times.
- Effluent gas analysis (O2 and CO2) showed less noise than DO measurements, suggesting improved reliability for feedback control.
Conclusions:
- Stirred tank reactors provide superior control for SCFs, eliminating the need for manual corrections.
- Dissolved oxygen or effluent gas analysis can reliably trigger harvesting, optimizing secondary metabolite production.
- SCFs are a stable and efficient method for microbial production, with potential for improved process control using gas analysis.
Related Concept Videos
01:18Bioreactor Controls-II
In aerobic fermentations, oxygen is vital for microbial growth and metabolite production. Since air comprises only about 20% oxygen and the gas is poorly soluble in water—just 9 ppm at 20°C—supplying sufficient oxygen becomes a critical challenge, especially in high-demand processes like yeast growth or citric acid production. Even a fully saturated broth may offer only a few seconds of oxygen availability.To address this, sterile or scrubbed air is introduced into the fermentor via a sparger...
01:29Bioreactor Design and Operational System
Bioreactors are engineered vessels designed to cultivate microorganisms under controlled conditions for industrial bioprocessing. They maintain sterility and allow precise regulation of pH, temperature, oxygen, and nutrient levels to optimize microbial growth and metabolite production. Bioreactors range from small laboratory units of 1 liter to industrial systems holding up to 500,000 liters, though only about 75% of their volume is actively used for fermentation. The remaining headspace...
01:14Scale-Up Processes
The scale-up of microbial fermentation processes is essential in industrial biotechnology, allowing the transition from laboratory-scale experiments to commercial-scale production while aiming to maintain product yield and quality. This process requires meticulous adjustment of equipment design, process parameters, and contamination control strategies to accommodate increasing culture volumes.At the laboratory scale, cultures are typically maintained in 1 to 10-liter glass or autoclavable...
01:27Production of Alcohol
Continuous fermentation is a key strategy in industrial ethanol production, particularly when efficiency, scalability, and high yields are essential. This approach allows for uninterrupted operation and optimized resource utilization. The primary feedstock, corn starch, undergoes enzymatic hydrolysis facilitated by α-amylase and glucoamylase. These enzymes break down the starch into fermentable sugars such as glucose, which are readily assimilated by fermentative microorganisms.Fermentation...
01:14Batch vs Continuous Culture
Fermentation is a foundational biotechnological process used to produce pharmaceuticals, biofuels, enzymes, and food additives. Among industrial strategies, batch and continuous fermentation are the two most widely applied. Although both rely on microbial conversion of substrates into desired products, they differ markedly in operation, productivity, and suitability for specific applications.Batch fermentation occurs in a closed system in which nutrient media and inoculum are added at the...
01:28Bioreactor Controls-I
Maintaining optimal conditions within fermenters is essential for maximizing microbial productivity and ensuring process efficiency. This lesson focuses on key parameters—temperature, foam, pH, carbon dioxide, oxygen, and pressure—and their precise measurement and control strategies in fermentation systems.Temperature ControlTemperature regulation is critical due to the exothermic nature of many fermentation processes. In small laboratory fermenters, temperature is commonly monitored using...