Determination of antimicrobial properties of different types of samples

We determine the antimicrobial properties of different types of samples, including plastics, particles, biological extracts, textiles, among others. We use different methodologies. For antibacterial tests we use the broth microdilution method for the determination of the minimum inhibitory concentration (MIC), the agar diffusion method (inhibition halo) and the surface activity analysis method. For antifungal assays, we quantified fungal micellar growth inhibition and spore germination. These techniques allow us to evaluate the ability of samples to inhibit microbial growth and determine their effectiveness as antimicrobial agents.

Methodology

1) Broth microdilution method: CIM is evaluated in 96-well microtitration plates. All plates (with positive and negative controls) are incubated at 35 1°C for 24 hours, and the turbidity of the wells (index of microbial development) is analyzed. Additionally, they can be sown on plates with nutrient medium to determine colony forming units (CFU).

2) Agar diffusion method: the material to be tested, either in well or disc, is placed on a solid culture medium previously inoculated with the micro-organism of interest. The plates are incubated at 24-48 h controlled temperature and antimicrobial activity is evidenced by the formation of the microbial growth inhibition halo around the tested samples.

3) Method of surface activity analysis: consists of the quantification of micro-organisms that come into contact with chemically modified polymer surfaces to be evaluated, and those recovered after 24 hours at 36°C. Antimicrobial activity is determined by comparing the results obtained between the control sample growth value and the treated sample growth value, before and after the determined contact time and subsequent plate culture (CFU determination). The reduction of microbial growth is calculated.

Implementing

Our service has applications in a wide range of industries, including food, medical, pharmaceutical, cosmetic, textile, among others.

Frequently asked questions

What types of micro-organisms are evaluated in antimicrobial assays?
In antimicrobial assays, different types of microorganisms can be evaluated, including:
- Gram-negative bacteria:
Escherichia coli: A non-pathogenic strain for humans, used as a model to evaluate antimicrobial activity against gram-negative bacteria.
Pseudomonas syringae: A common phytopathogenic bacteria that affects a variety of crops, especially tomatoes.
- Gram-positive bacteria:
Bacillus thuringiensis: A bacterium used in biological pest control, but can also be used as a microorganism to evaluate antimicrobial activity against gram-positive bacteria.
- Plant pathogenic fungi:
Fusarium solani: A fungus that causes diseases in a wide range of plants, including agricultural crops, vegetables and trees.
Botrytis cinerea: A fungus that causes gray rot in many plants and is especially problematic in high humidity conditions.

It is important to note that these tests are carried out with pathogenic microorganisms for humans, as part of the evaluation of products or substances with antimicrobial potential.

Technical Responsible

Dr. Andrea Yamila Mansilla
2235186382
amansill@mdp.edu.ar