Monitoring Bacterial Growth in Distinct Media Formulations with an Automated Microbioreactor
JoVE Encyclopedia of Experiments
Microbiology
0 views • 2:51 min • November 28th, 2025
Take the culture of a genetically modified bacterium engineered to harbor a plasmid that expresses a secretory fluorescent protein and confers antibiotic resistance.
Inoculate it into a medium containing the antibiotic and incubate with shaking to promote bacterial growth.
The antibiotic ensures that only cells retaining the plasmid can proliferate.
Once the culture reaches the desired density, transfer it to an automated liquid-handling system.
A deep-well plate contains varying concentrations of essential nutrients, which are dispensed into a microtiter plate to create distinct media formulations.
Inoculate each well of the plate with the bacterial culture.
Seal the plate and place it into a microbioreactor, which maintains uniform temperature and aeration.
The different formulations lead to variations in bacterial growth and fluorescent protein secretion.
An optical sensor in the device measures cell density and fluorescence, enabling comparison of bacterial growth and fluorescent protein production across the media formulations.
Sterilize deep well plates for stock solution storage on a work table by wiping the plates with 70 percent ethanol and subsequently drying them in a laminar flow hood. Start the seed culture by inoculating 50 milliliters of BHI medium containing 25 milligrams per liter of kanamycin with one aliquot from the working cell bank. Place all necessary labware on the robotic work table and pour stock solutions in the corresponding labware.
Then, start the robotic work flow for media preparation so that the last step, which is the inoculation, is reached in time for the start of seed culture. Sample the seed culture after approximately two hours to monitor the growth by measuring the optical density at 600 nanometers or OD600. Continue to monitor the growth at each hour.
After approximately five hours, the culture reaches an OD600 between three and four, and is used to inoculate the main cultures. Place the seed culture on the liquid handler work table and continue the media preparation protocol. Seal the cultivation microtiter plates after inoculation.
Next, place the sealed cultivation MTP in the Biolector device. Then, start the predefined cultivation protocol.
Overview
This article details a method for culturing genetically modified bacteria that express a fluorescent protein and confer antibiotic resistance. The process involves inoculating the bacteria into a nutrient medium, monitoring growth, and analyzing protein secretion using an automated system.
Key Study Components
Area of Science
- Microbiology
- Genetic Engineering
- Biotechnology
Background
- Genetically modified bacteria can be used to study protein expression.
- Antibiotic resistance allows for selective growth of modified strains.
- Fluorescent proteins serve as markers for successful expression.
- Automated systems enhance efficiency in culturing and analysis.
Purpose of Study
- To develop a reliable method for culturing genetically modified bacteria.
- To analyze the effects of different nutrient formulations on bacterial growth.
- To measure fluorescent protein production as an indicator of successful expression.
Methods Used
- Inoculation of bacteria into antibiotic-containing media.
- Use of automated liquid-handling systems for media preparation.
- Monitoring of bacterial growth using optical density measurements.
- Fluorescence measurement to assess protein expression levels.
Main Results
- Successful growth of bacteria was achieved in selective media.
- Variations in nutrient concentrations influenced growth rates.
- Fluorescent protein production correlated with bacterial density.
- Automated systems provided consistent and reproducible results.
Conclusions
- The method allows for efficient culturing and analysis of modified bacteria.
- Different nutrient formulations can optimize protein expression.
- Automated systems are valuable tools in microbiological research.
Frequently Asked Questions
Executive Industry Relevance
Automated microbioreactor platforms enable high-throughput, quantitative assessment of bacterial growth and recombinant protein production across diverse media conditions. This capability supports early-stage bioprocess optimization, de-risking strain selection, and accelerating the translation of microbial expression systems for biopharma R&D. Real-time optical measurements provide actionable data for portfolio triage and process development decisions.
Strategic Applications in Biopharma R&D
Early Discovery & Target Validation
- Enables systematic interrogation of nutrient effects on recombinant protein yield in engineered strains.
- Supports biological de-risking by revealing growth and expression variability across conditions.
- Facilitates predictive confidence in strain and media selection for downstream development.
Screening & Assay Development
- Prepares validated microbial systems for scalable protein production workflows.
- Standardizes growth and expression assays using automated, reproducible protocols.
- Generates quantitative outputs for comparative evaluation of media formulations.
- Enables reliable screening of strain-media combinations for optimal performance.
Translational & Preclinical Research
- Aligns microbial production conditions with translational process requirements.
- Supports continuity from discovery-stage optimization to preclinical material supply.
- Reduces risk of late-stage process failure by identifying robust growth conditions early.
Pipeline & Workflow Integration
This automated microbioreactor workflow integrates into the early discovery-to-lead identification continuum, providing a foundation for scalable protein production and process development.
- Discovery Biology: Supports hypothesis testing on nutrient impact and strain performance.
- Screening: Delivers reproducible, quantitative growth and expression data for condition comparison.
- Analytics: Provides real-time optical density and fluorescence measurements for robust statistical analysis.
- Translational Research: Bridges early optimization with preclinical process requirements for microbial systems.
- Enterprise Reuse: Establishes a standardized, reusable platform for ongoing strain and media evaluation.
Operational & Enterprise Impact
- Scientific Value: Increases predictive confidence in microbial production system selection.
- Operational Value: Enhances reproducibility and throughput via automation and standardized protocols.
- Strategic Value: Improves go/no-go decisions for strain and media advancement, reducing late-stage risk.
- Portfolio Impact: Enables risk-adjusted prioritization of microbial expression systems for development.
Implementation Considerations
- Requires expertise in microbial genetics and bioprocess engineering.
- Needs access to automated liquid handling and microbioreactor instrumentation.
- Demands cross-team standardization of assay protocols and data analysis.
- Adaptation may be needed for different microbial hosts or protein targets.
- Throughput and scalability are limited by plate and device capacity.
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Last updated: 29 August 2026