Antimicrobial Activity Assay
Antimicrobial Activity Assay - Related Videos
06:01
A Dye Release Assay to Quantify Enzymatic Activity of Antimicrobial Proteins
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2025
This video demonstrates the dye release assay for quantifying the enzymatic activity of antimicrobial proteins. The antimicrobial protein degrades the bacteria's dye-labeled cell wall and releases the dye molecules turning the solution blue. The absorbance of the solution correlates with the enzymatic activity of the antimicrobial protein.
03:37
Assessing the Antimicrobial Activity of Nisin Variants Using an Agar Well Diffusion Assay
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2025
Source: Nickling, J. H., et.al. Antimicrobial Peptides Produced by Selective Pressure Incorporation of Non-canonical Amino Acids. J. Vis. Exp. (2018)This video demonstrates an agar well diffusion assay used to evaluate the antimicrobial activity of nisin variants. It shows how Lactococcus lactis expressing the membrane-bound peptidase NisP activates nisin precursors produced in E. coli, resulting in growth inhibition halos. The size of these halos reflects the bioactivity of each nisin variant.
11:10
Expression, Purification, and Antimicrobial Activity of S100A12
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Cited by 14 •
2017
Here, we present a method to express and purify S100A12 (calgranulin C). We describe a protocol to measure its antimicrobial activity against the human pathogen H. pylori.
10:50
Qualitative and Quantitative Assays for Detection and Characterization of Protein Antimicrobials
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Cited by 11 •
2016
Here, we present protocols to rapidly screen and characterize enzymes for antimicrobial activity. The microslide diffusion assay and the dye-release assay utilize target bacterial substrates for qualitative and quantitative enzymatic activity evaluation.
01:38
Assessment of the Antimicrobial Activity of a Nanoparticle Composite Against Pathogenic Bacteria
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2026
Take tubes with a medium containing a nanoparticle composite, engineered from a combination of transition metals and carbon.Introduce antibiotic-resistant Gram-positive and Gram-negative pathogenic bacteria into separate tubes as test samples.Include untreated bacteria as a negative control and antibiotic-treated bacteria as a positive control.Incubate the samples with shaking.In Gram-negative bacteria, the porous outer membrane and thin peptidoglycan layer facilitate nanoparticle entry,...
FAQs
The readout determines what aspect of antimicrobial action is captured. A growth inhibition zone shows how far visible growth is prevented, whereas turbidity changes reflect differences in overall culture growth. Viable-cell counts instead indicate how many cells remain capable of survival. Selecting among these measurements affects whether the result emphasizes growth suppression, remaining viability, or a concentration-based comparison.
Minimum inhibitory concentration, or MIC, provides a concentration-based endpoint rather than only a visible growth comparison. It can support quantitative comparisons of antimicrobial potency among candidate compounds, natural products, immune-derived molecules, or therapeutic agents. Including this endpoint helps connect the observed microbial response with the concentration dimension of the tested substance.
Target selection is central because the assay may examine bacteria, fungi, or other microorganisms, and the result describes activity against the target tested. Reporting resistance or susceptibility patterns adds context beyond a single inhibition value. This distinction helps researchers determine whether an observed response is associated with the microorganism under study and interpret the finding appropriately.
A basic workflow begins by exposing the selected microorganism to the substance being evaluated. The assay then measures the response through a chosen endpoint, such as inhibition zones, turbidity, viable-cell counts, or MIC. Matching the exposure and readout to the research question allows the experiment to report growth effects, surviving cells, or antimicrobial potency.
Antimicrobial activity assays are useful during screening of natural products and candidate drugs because they permit activity to be evaluated before more focused development. Researchers can compare how strongly different substances affect microbial growth or survival, using the selected quantitative readout. These measurements help prioritize substances for further investigation rather than relying on a qualitative impression alone.
In immunology and infection research, these assays can test immune-derived molecules, host secretions, and therapeutic agents against microorganisms. Their results help show whether such substances influence microbial survival and can reveal susceptibility or resistance patterns. That information connects host or treatment-related factors with microbial outcomes and supports investigation of potential anti-infective strategies.