Comparison of ACES, MOPS, and MOPSO in Yeast Extract Media

Comparison of ACES, MOPS, and MOPSO in Yeast Extract Media

In microbiological cultures, the choice of buffer is crucial for the effectiveness of the medium. This article compares three commonly used buffers – ACES, MOPS, and MOPSO – in Buffered Charcoal Yeast Extract (BCYEα) medium, especially focusing on their culturing effects on Legionella pneumophila.
ACES is typically added to BCYEα medium for culturing Legionella pneumophila. BCYEα medium, with a pH of 6.9, usually contains ACES and L-cysteine to create a suitable environment for the growth of Legionella pneumophila.

Motivation for the Study

Researchers aim to explore whether replacing ACES with MOPS and MOPSO, which are cheaper and more stable buffers, could maintain culturing effectiveness while reducing costs.

Objectives and Applications of the Study

- Research Objectives for Legionella pneumophila

  • Public Health Protection
  • Understanding the transmission and infection mechanisms of Legionnaires' disease aids in formulating effective public health policies.
  • Diagnostic Technology Development
  • Improving rapid diagnostic methods enhances early identification of infections, improving treatment outcomes.
  • Treatment Improvement
  • Studying the bacterium's biological characteristics may reveal new therapeutic targets and aid in combating drug-resistant strains.

- Research Applications

  • Environmental Monitoring
  • Developing more effective detection and monitoring technologies can prevent large-scale outbreaks in artificial water systems.
  • Vaccine Development
  • Understanding immune evasion mechanisms helps in developing effective vaccines for long-term protection of high-risk populations.
  • Microbial Ecology
  • Studying the bacterium's survival and spread in natural environments aids in understanding microbial ecosystem dynamics for environmental protection and restoration.

- Research History of Legionella pneumophila

  • Discovery and Early Studies
  • Legionella pneumophila was first identified during a 1976 pneumonia outbreak at an American Legion convention in Philadelphia, becoming a significant public health event. Subsequent research confirmed it as a novel pathogen, categorized as a waterborne bacterium.
  • Culturing and Identification
  • Initially challenging, culturing Legionella pneumophila was facilitated by BCYEα medium, which provided essential nutrients like L-cysteine and iron.
  • Challenges Encountered
    • Difficulty in Environmental Monitoring: Low concentrations of Legionella pneumophila in natural and artificial water environments make detection and monitoring challenging.
    • Delayed Diagnosis: Traditional culturing methods take days, delaying diagnosis and potentially increasing mortality rates.
    • Antibiotic Resistance: Some strains exhibit antibiotic resistance, posing new challenges to treatment.
  • Innovative Approaches
    • Molecular Diagnostic Techniques: Modern techniques like PCR significantly shorten diagnosis time, improving treatment timeliness and effectiveness.
    • Environmental Detection Technologies: New technologies like real-time quantitative PCR (qPCR) enable rapid detection in water systems, facilitating early outbreak detection and control.
    • Genomic Studies: Genomics deepen understanding of Legionella pneumophila's pathogenic mechanisms and drug resistance genes, aiding targeted therapy development.

Introduction to Buffers

- ACES(N-(2-Acetamido)-2-aminoethanesulfonic acid)

  • A commonly used biological buffer with a pKa of 6.8 (25°C), widely applied in BCYEα medium for culturing Legionella pneumophila. However, it is relatively costly and prone to degradation over prolonged use.

- MOPS(3-(N-Morpholino)propanesulfonic acid)

  • A buffer with a pKa of 7.2 (25°C), extensively used in biochemistry and cell culture due to its lower cost and stability compared to ACES. It can substitute for ACES in BCYEα medium, especially in cost-reducing applications.

- MOPSO(3-(N-Morpholino)-2-hydroxypropanesulfonic acid)

Similar to MOPS with a pKa of 7.2 (25°C), MOPSO offers comparable stability and cost-effectiveness. It can also be used in BCYEα medium and has shown similar effectiveness to ACES in certain studies.

Purposes of Buffer Use

Buffers in media primarily maintain stable pH levels crucial for microbial growth and metabolism. Different buffers have varying characteristics in pH range, cost, and stability, suitable for different experimental needs.

Buffer Comparison (Table)

Buffer pKa (25°C) Cost Stability Features
ACES 6.8 Relatively high Prone to degradation Typically added to BCYEα medium for culturing Legionella pneumophila.
MOPS 7.2 Relatively low Stable

Can substitute for ACES, showing similar effectiveness, especially in cost-reducing applications.

MOPSO 7.2 Relatively low Stable

Can substitute for ACES, showing similar effectiveness to ACES in F889 strain studies.

Research Results

- Culturing Effectiveness of F889 Strain

Culturing F889 strain of Legionella pneumophila using ACES, MOPS, and MOPSO showed no significant differences, indicating MOPS and MOPSO can effectively replace ACES.

- Cytotoxicity

The cytotoxicity of the F889 strain was unaffected by buffer substitution. However, further research is needed to determine the effect of buffer substitution on all Legionella pneumophila strains.

- Multi-Strain Testing

Testing nine Legionella pneumophila strains showed no significant difference in culturing effectiveness between ACES and MOPS, further supporting the feasibility of MOPS as a substitute.

How to Choose the Right Buffer for Your Medium?

- Sales Channels

ACES is primarily available through manufacturers of BCYEα medium or institutions testing for Legionella pneumophila. Institutions with a high demand for buffers typically opt for ACES.

- Cost-effectiveness

For customers accepting slight differences in buffering capacity, testing the lower-cost MOPS is recommended. Although ACES has a pKa of 6.8 (25°C), closer to the pH of BCYEα medium, MOPS with a pKa of 7.2 (25°C) still provides sufficient buffering capacity for practical applications at a lower cost.


This study compared three buffers in BCYEα medium, showing that MOPS and MOPSO can effectively replace ACES, especially with the F889 strain. Considering cost-effectiveness, MOPS is recommended as a substitute for ACES in applications tolerating slight differences in buffering capacity. Further research is needed to assess the response of other Legionella pneumophila strains to buffer substitution comprehensively.

Further reading:Useful pH range of Biological Buffers
Further reading:How to choosing the biological buffer you need: By ph and pKa
Further reading:Why use MOPS?
Further reading:What is a Good's Buffer?

Release date:2024.06.19