Adhesion Assays to Human Intestinal Monolayers

The correct individual balance of the microbiota plays a key role in maintaining the health of the host. The presence of bacterial pathogens can alter the homeostasis (composition and activity of the microbiota) of the intestinal bacteria, leading to an increase in disease risk or specific diseases. Probiotics are viable and beneficial microorganisms that have health effects on the host. Therefore, the evaluation of adhesion properties and pathogen competitive rejection constitutes an important point in the characterization of probiotics.


Probiotics, defined as living microorganisms, are viable microbial feed supplements. When applied to humans or animals in the form of stem cells or fermented products, they can benefit the host by improving the characteristics of local microbiota. The host’s intestinal epithelium is the first barrier against foodborne pathogens and is supported by the mucosal immune system that is closely connected to the gastrointestinal barrier. The first and important step for probiotics to play a role is to adhere and colonize the epithelial cells of the gastrointestinal tract. Therefore, adhesion to the intestinal surface is considered to be a prerequisite for effective probiotic strains.

Mechanism of probiotics in pathogen adhesion. Fig.1 Mechanism of probiotics in pathogen adhesion. (Collado, 2010)

Introduction of Adhesion Assays

It is very difficult to study bacterial adhesion in vivo and to avoid unnecessary use of animals in research projects and for ethical considerations, many highly differentiated cell lines have been developed to establish functions equivalent to their in vivo counterparts. In contrast to more expensive animal trials, cell line models are cost-effective and can be used for large-scale screening. Besides, the cell line model conforms to 3R paradigms: reduction, refinement, and replacement.

Most of the in vitro models used to study the adhesion ability of probiotics are based on human intestinal cell lines. One of the models is the Caco-2 cell line derived from human colon cancer. The mechanism of this study is that the cell line differentiated spontaneously under standard culture conditions, and the differentiated Caco-2 cell monolayer showed the characteristics of mature intestinal cells. Using Caco-2 cell culture to screen probiotics, you can study the adhesion mechanism of specific probiotics.

Adhesion Assays at Creative Biolabs

Creative Biolabs is committed to understanding, predicting, and controlling health-related probiotic-host interactions. In particular, we combine interdisciplinary knowledge to seek to understand how bacteria adhere to surfaces and how to control adhesion. Our service advantages include:

  • We provide a variety of cell lines to study the adhesion of probiotics under static or dynamic conditions;
  • Similar to all other unverified tests, clients are completely free to develop their protocols so that the tests are fully suitable for their specific requirements;
  • Possess a variety of analysis methods (crystal violet method, fluorescence method, microscopy (wide-field, confocal laser scanning microscope, scanning electron microscopy), real-time quantitative PCR, etc.), which can abundantly characterize the physiological and biochemical mechanisms of bacterial adhesion observed.

If you are interested in our service, please feel free to contact us.


  1. Collado, M. C., et al. Probiotics in adhesion of pathogens: mechanisms of action. Academic Press. 2010: 353-370.

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