THE SET OF MICROORGANISMS THAT HABITUALLY INHABIT THE HUMAN BODY, KNOWN AS “MICROBIOMA”, PERFORMS A SERIES OF BENEFICIAL FUNCTIONS FOR OUR HEALTH, SOME OF WHICH ARE BEGINNING TO UNDERSTAND AND CHARACTERISE. IN THIS PROJECT, WE INTEND TO USE THE TECHNIQUES OF MASS SEQUENCING, METAGENOMICA AND MOLECULAR MICROBIOLOGY TO CHARACTERISE THE ORAL MICROBIOTA IN CONDITIONS OF HEALTH AND DISEASE, AND USE THIS INFORMATION FOR THE DEVELOPMENT OF DIAGNOSTIC AND PREVENTIVE STRATEGIES. THE PROJECT CONSISTS OF THREE MAIN WORK PACKAGES: 1) ORAL MICROBIOTA DEVELOPMENT FROM BIRTH TO 7 YEARS OF AGE IN CHILDREN WHO SUFFER AND DO NOT HAVE CAVITIES. SAMPLES AT 3, 6, 12, 24 AND 84 MONTHS OF AGE WILL BE USED IN A COHORT OF SWEDISH CHILDREN, HALF OF WHOM DEVELOP CARIES, TO STUDY THE DEVELOPMENT OF THE MICROBIOTA ASSOCIATED WITH GOOD ORAL HEALTH AND THAT CARIOGENICA, USING ILLUMINA SEQUENCING OF THE RIBOSOMAL GENE, IN ADDITION TO MEASURING BACTERIAL AND FUNGIC LOAD OVER TIME AND LEVELS OF IMMUNOGLUBULIN TO SALIVA. 2) CHARACTERISATION OF BENEFICIAL FUNCTIONS BY THE ORAL MICROBIOME, IN PARTICULAR THE TAMPON EFFECT ON PH, AND THE REDUCTION OF NITRATE. THE BUFFER EFFECT OF DENTAL PLAQUE IS DUE TO METABOLIC PATHWAYS SUCH AS UREASE OR ARGINOLITICA ACTIVITY, WHICH LEAD TO THE PRODUCTION OF AMMONIUM, WHICH NEUTRALISES THE ACIDS CAUSING THE DEMINERALISATION OF THE ENAMEL. IN ADDITION, PH NOT ONLY AFFECTS THE RISK OF DENTAL CARIES, BUT ALSO THE DIGESTION OF CARBOHYDRATES, DUE TO THE IMPORTANCE OF PREDIGESTION THAT TAKES PLACE IN THE MOUTH, WHERE THE ALPHA-AMYLASE RESPONSIBLE FOR THIS PROCESS HAS AN OPTIMAL PH OF 6.7 TO 7. THE NITRATE REDUCTASE ACTIVITY OF ORAL BACTERIA IS ALSO FUNDAMENTAL FOR THE PRODUCTION OF NITRIC OXIDE, WHICH HAS A CLEAR SYSTEMIC EFFECT ON CARDIOVASCULAR HEALTH, AMONG OTHER IMPORTANT PHYSIOLOGICAL EFFECTS; 3) CHARACTERISATION OF THE MICROBIOTA AND THE METABOLIC PATHWAYS ASSOCIATED WITH HALITOSIS, BY MASS SEQUENCING OF METATRANSCRIPTOMA. THIS DISEASE, WHICH DOES NOT YET HAVE EFFECTIVE THERAPEUTIC MEASURES, IS CAUSED BY THE PRODUCTION OF VOLATILE COMPOUNDS BY ORAL BACTERIA, AND THE ETHIOLOGIC AGENTS OF IT ARE NOT ELUCIDATED, ALTHOUGH IT IS KNOWN TO HAVE A POLYMICROBIAL ORIGIN. By means of the bio-informatics of GENES EXPRESED IN HEALTH AND HALITOSIS CONDITIONS, we may identify the active MICROORGANISMS AND EXPRESSED GENES RESPONSIBLE OF PATOGENICA ACTIVITY._x000D_ THIS INFORMATION WITH TWO FINES APPLICED: _x000D_ 1) THE DEVELOPMENT OF MOLECULAR DIAGNOSTIC KITS determining the TAMPON capacity of the platform (UREASA AND ARGININOLITIC ACTIVITY) and NITRIT PRODUCTION CAPACITY OF ORAL MICROBIOMA (REDUCTOR NITRATE ACTIVITY); THESE TESTS WERE USED TO RELATE TAMPON CAPACITY TO THE RISK OF CARIES AND DIGESTIVE PROBLEMS, AS WELL AS TO RELATE THE PRODUCTION CAPACITY OF NITRITE TO BLOOD PRESSURE, WHICH COULD EXPLAIN THE EPIDEMIOLOGICAL CORRELATION BETWEEN ORAL DISEASES AND CARDIOVASCULAR RISK. _x000D_ 2) SELECTION OF probiotic SPECIES, WHAT WHAT IS Isolated OF INDIVIDUUS WITHOUT THE PATOLOGY OF CORRESPONDIENT IN THE NICHOUSE WHERE WHERE YOUR ACCOUNT MUST BE YOUR ACCOUNT, AND YOU CAN BE USED AS PREVENTIVE STRATEGIES FROM THE CARIES, THE MALA ABSORCTION OF CARBOHYDRATS, HALITOSIS AND CARDIOVASCULAR DISEASES.