Investigation of the interaction between lactic acid bacteria in human saliva

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INRAE presentation

The French National Research Institute for Agriculture, Food, and Environment (INRAE) is a major player in research and innovation. It is a community of 12,000 people with 272 research, experimental research, and support units located in 18 regional centres throughout France. Internationally, INRAE is among the top research organisations in the agricultural and food sciences, plant and animal sciences, as well as in ecology and environmental science. It is the world’s leading research organisation specialising in agriculture, food and the environment. INRAE’s goal is to be a key player in the transitions necessary to address major global challenges. Faced with a growing world population, climate change, resource scarcity, and declining biodiversity, the Institute has a major role to play in building solutions and supporting the necessary acceleration of agricultural, food and environmental transitions.

Work environment, missions and activities

Lab:

AFIM team, UMR PAM, l’Institut Agro Dijon, France

(https://umr-pam.fr/en/our-teams/food-fermentation-interaction-microbiota-afim)

The internship will be conducted within the AFIM team of the UMR PAM, in collaboration with the FFOPP team of the UMR CSGA (https://www2.dijon.inrae.fr/csga/site_engl/equipe_1.php)

Context and objectives:

The oral cavity experiences a significant influx of microorganisms, particularly lactic acid bacteria (LAB), during the consumption of fermented foods. However, the interactions between the oral cavity and LAB remain underexplored. In a study using a rat model, we demonstrated a considerable interindividual variability in the persistence of LAB in the hours following the consumption of fermented food (1-3). Our ongoing research indicates that certain variations in salivary biochemistry are correlated with LAB persistence in this rat model, thus partially explaining this variability. Furthermore, we have also found associations between taste perception and the composition of the oral microbiota (4, 5). The activity of LAB in the mouth has not yet been evaluated. Active LAB from fermented foods could directly modulate oral biology, including sensory perception. They also could modulate the oral microbiota, which could, in turn, affect sensory perception.

During this internship, the student will investigate the interaction between LAB and human saliva by exploring LAB activities in relation to the biological properties of saliva. The research may involved a variety of methodologies such as chromogenic or fluorescent probes, enzymatic activity assays, targeted gene expression analysis, microscopy, and cloning techniques.

This project offers a unique opportunity to deepen our understanding of LAB in the oral cavity and their impact on sensory perception, with potential applications in improving the quality of life for individuals with eating behaviour disorders. The project is funded by the French National Research Agency (ANR) and may be extended into a PhD opportunity.

References:

1.            Ibarlucea-Jerez M, Monnoye M, Chambon C, Gerard P, Licandro H, Neyraud E. 2024. Fermented food consumption modulates the oral microbiota. NPJ Sci Food 8:55.

2.            Ibarlucea-Jerez M, Canivenc-Lavier MC, Beuvier E, Barbet P, Menetrier F, Neyraud E, Licandro H. 2022. Persistence of fermented food bacteria in the oral cavity of rats after one week of consumption. Food Microbiol 107:104087.

3.            Ibarlucea-Jerez M. 2022. Persistence of lactic acid bacteria from fermented foods in the oral cavity of rats, potential links with oral microbiota, salivary composition and taste perception. PhD. thesis. Université Bourgogne Franche-Comté.

4.            Feng Y, Licandro H, Martin C, Septier C, Zhao M, Neyraud E, Morzel M. 2018. The Associations between Biochemical and Microbiological Variables and Taste Differ in Whole Saliva and in the Film Lining the Tongue. Biomed Res Int 2018:2838052.

5.            Licandro H, Truntzer C, Fromentin S, Morabito C, Quinquis B, Pons N, Martin C, Blottiere HM, Neyraud E. 2023. The bacterial species profiles of the lingual and salivary microbiota differ with basic tastes sensitivity in human. Sci Rep 13:20339.

Training and skills

Desired Skills and Qualifications:

• Final-year Master’s student or equivalent (e.g., engineering school)
• Strong background in microbiology, biochemistry, or a related field
• Experience with laboratory techniques such as culture of microorganisms, enzymatic assays, microscopy, and molecular biology
• Ability to quickly become autonomous and reliable in conducting experiments
• Proficiency in researching and analysing scientific literature, particularly methodological information
• Analytical thinking and problem-solving abilities
• Good communication skills and ability to work collaboratively

How to apply

Application process:

Please send the following documents to helene.licandro@agrosupdijon.fr:

• CV
• cover letter
• letter(s) of recommendation or contact details of previous internship supervisors.