Characterization of Fecal Microbiota in a Population Aged 50 to 75 Years Targeted by Seasonal Vaccination

The goal of this interventional study is to constitute a biological samples collection collected from healthy elderly volunteers and used for scientific purposes.

The main questions it aims to answer are:

* Improving knowledge of the composition of the gut microbiota
* Identify, isolate and culture microbiota species of interest in the field of health ageing or used as therapeutics associated to the vaccination
* Determining the correlation between the gut microbiota composition and the immune response of individuals.

The compositional analysis of commensal bacterial populations collected from a variety of clinical samples has been recently made possible with the availability of Next Generation Sequencing (NGS) technologies. The term 'next-generation probiotics' (NGP) is now widely used to describe these commensal species of potential health interest.

However, this approach is still hampered by the fact that there are usually few or even no strains available for a number of commensal species.

In this context, BIOASTER has developed a specific technological process based on flow cytometry analysis and then sorting under strictly anaerobic conditions to target and cultivate commensal species of interest.

The goal of this study is to constitute a biological samples collection from elderly people, to proceed with the isolation of beneficial commensal strains such as Faecalibacterium prausnitzii, Akkermansia muciniphila and Oscillospiraceae, in a non-limitative way.

BIOASTER's objective is to strengthen technological support, provide new knowledges and tools for the development of next-generation products. Numerous biotherapeutics companies will benefit from this pipeline, ultimately improving the chances of survival in life-threatening diseases with unmet medical needs.

Elderly people will be recruited by the investigational unit Biofortis.

Blood (Whole blood + TruCulture tubes) and feces will be collected from each volunteer.

Eligibility Criteria:
Inclusion Criteria:

* Subjects aged between 50 and 75,
* BMI between 18.5 and 29 kg/m2,
* Normal clinical examination,
* Written consent obtained

Exclusion Criteria:

* Diagnosed acute or chronic gastrointestinal disease or complication (e.g., celiac disease, gastroesophageal reflux, gastric or duodenal ulcer, Crohn's disease, hemorrhoids, irritable bowel syndrome)
* Infectious gastrointestinal event within 3 months prior to inclusion
* Severe chronic disease (active cancer, HIV, severe renal failure, ongoing severe heart or liver or biliary disorders, arthritis) or severe chronic disease deemed incompatible with the conduct of the study by the investigator
* Major surgical procedure likely to disrupt the intestinal microbiota, within 6 months prior to inclusion
* Recent food allergy \< 3 months prior to inclusion
* Antibiotic, antiviral, antifungal, proton pump inhibitor or any other treatment likely to disrupt the microbiota in the 3 months prior to inclusion
* Previous or current use of a treatment that may disrupt the microbiota (e.g. laxatives, antidiarrheals, antacids...) in the last 3 months
* Significant change in dietary habits or physical activities in the 3 months prior to inclusion
* Consumption of more than 2 standard glasses of alcoholic beverages per day
* Smoking \> 20 cigarettes per day, illicit drug use,
* Daily use of non-steroidal anti-inflammatory drugs (NSAIDs)
* Severe psychiatric or neurological pathology
* Subject with liquid stools (Bristol Score = 7) or very hard stools (Bristol Score = 1)
* Any vaccination in the last month before inclusion
* Subject unable to understand the purpose of the research, answer questions and give their decision to participate in the study
* Subject already included in another research study involving the human subject
* Subject under guardianship and whose guardianship objects to the participation of his/her protectee,
* Subject not affiliated with a social security plan or not a beneficiary of such a plan