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Antimicrobial assay
Community analysis Heterologous expression system in vivo model Microbe-host interactions Microbial biochemistry Microbial biofilm Microbial cell biology Microbial genetics Microbial metabolism Microbial physiology Microbial proteomics Microbial signaling Pathogen detectionQualitative and Quantitative Methods to Measure Antibacterial Activity Resulting from Bacterial Competition
In the environment, bacteria compete for niche occupancy and resources; they have, therefore, evolved a broad variety of antibacterial weapons to destroy competitors. Current laboratory techniques to evaluate antibacterial activity are usually labor intensive, low throughput, costly, and time consuming. Typical assays rely on the outgrowth of colonies of prey cells on selective solid media after competition. Here, we present fast, inexpensive, and complementary optimized protocols to qualitatively and quantitively measure antibacterial activity. The first method is based on the degradation of a cell-impermeable chromogenic substrate of the β-galactosidase, a cytoplasmic enzyme released during lysis of the attacked reporter strain. The second method relies on the lag time required for the attacked cells to reach a defined optical density after the competition, which is directly dependent on the initial number of surviving cells.
Key features
• First method utilizes the release of β-galactosidase as a proxy for bacterial lysis.
• Second method is based on the growth timing of surviving cells.
• Combination of two methods discriminates between cell death and lysis, cell death without lysis, or survival to quasi-lysis.
• Methods optimized to various bacterial species such as Escherichia coli, Pseudomonas aeruginosa, and Myxococcus xanthus.
Graphical overview
Evaluation of Toxicity with Brine Shrimp Assay
The in vivo toxicity of new metallodrugs either as Small Bioactive Molecules (SBAMs) or Conjugates of Metals with Drugs (CoMeDs) or their hydrogels such as with hydroxyethyl-methacrylate (HEMA) (pHEMA@SBAMs or pHEMA@CoMeDs) are evaluated by the brine shrimp assay. Thus individuals of Artemia salina larvae are incubated in saline solutions with SBAMs, CoMeDs, pHEMA@SBAMs or pHEMA@CoMeDs or without for 24 h. The toxicity is then determined in terms of the mortality rate of brine shrimp larvae. Brine shrimp assay is a low cost, safe, no required feeding during the assay, while it requiring only a small amount of the tested agent.
Neutrophil Extracellular Trap Killing Assay of Candida albicans
Quantification of Trypanosoma cruzi in Tissue and Trypanosoma cruzi Killing Assay
Gentamicin Protection Assay to Determine Bacterial Survival within Macrophages
Isolation of Neutralizing Antibody
H2O2 Kill Assays of Planktonic Stationary Phase Bacteria
