Effect Evaluation And Functional Genes Exploration Of L.Plantarum CCFM8724 In Preventing Early Childhood Caries

Dental caries,as a common chronic oral disease,has a serious impact on people’s life and work.Early Childhood Caries(ECC)has a harmful to the physical and mental development and aesthetics of young children with the characteristics of younger age(3-6 years old)and high incidence.According to the theory of oral ecology,ECC is mainly related to the imbalance of oral microbiota,and some bacteria can be used as key genera of ECC,which provides a theoretical basis for early detection and treatment of ECC.For the treatment of ECC,some studies have shown that probiotics can be used as an exogenous bacterial supplement to prevent and treat ECC by regulating the composition of oral microbiota and inhibiting the growth of some bacteria.In this study,dental plaques were collected from dental caries and healthy parts of children with ECC,and dental plaque of healthy children was used as control to explore the characteristics of oral flora of children with different health status,and to screen out the key bacteria of different health status.In view of these bacterial differences,oral Lactobacillus plantarum CCFM8724 and placebo were given to children with ECC to explore the effects of Lactobacillus plantarum CCFM8724 on key bacteria,oral microecology and some common pathogenic bacteria of ECC.Under the premise of the effectiveness of probiotics,the unique genomic characteristics and functions of Lactobacillus plantarum CCFM8724 were further explored through genomics,so as to lay a genetic foundation for targeted screening of probiotics resistant to ECC in the future.The main results of the study are as follows:(1)By comparing the oral microbiota of caries lesions and healthy sites of children with ECC,and taking the oral microbiota of healthy children as controls,it was determined that there was no significant difference in α diversity among the three groups,but there was a certain difference in β diversity.The oral microbiota structure of healthy children was more s Table.Significant differences in the oral microbiota structure were observed between carious lesions and healthy sites for each child with ECC.The genera in the oral cavity of healthy children included Neisseria,Leptotrichia,Porphyromonas and Gemella.In caries lesions sites,the main genera were Lactobacillus,Veillonella and Prevotella 7.The oral microbiota of healthy sites of children with ECC mainly includes Actinomyces,Bifidobacterium and Abiotrophia.The healthy group had the most complex co-occurence networks.The random forest model composed of 10genera(Prevotella 7,Actinobacillus,etc.)had a certain clinical diagnostic ability,and the prediction accuracy rate was 89.8%.These results confirmed that the oral microbiota could be used for early prediction and prevention of ECC from an ecological point of view,and provided a certain reference for future dietary intervention,probiotics or antibiotic targeted therapy.(2)By recruiting ECC children and implementing a 6-week randomized,double-blind,placebo-controlled clinical trial(intervention period of 4 weeks,washout period of 2 weeks),it was found that compared with the control cohort,L.plantarum CCFM8724 could significantly reduce the amounts(log DNA copies/ng)of Streptococcus mutans and Candida albicans in the oral cavity.In terms of oral microecology,L.plantarum CCFM8724 improved the composition and functional genes of oral microbiota,manifested as the abundance of Firmicutes,Streptococcus,Granulicatella and Gemella increased,while the abundance of Proteobacteria,Bifidobacterium and Catonella decreased.In the functional genes,L.plantarum CCFM8724 increased the abundance of enzymes related to metal ions,RNA transport.In addition,L.plantarum CCFM8724 significantly improved the co-occurence networks complexity of 10 biomarkers.This study expanded the application scope of L.plantarum CCFM8724 and provided new suggestions for the prevention and control of ECC in the future.(3)Based on the determination of the clinical effectiveness of probiotics,the genomic information of L.plantarum CCFM8724 was further determined by comparative genomics.The results showed that the genome length of 13 strains L.plantarum as controls were 2.57-2.80 Mb,and the GC content were 45.1%-45.7%.The genome length of CCFM8724 was 2.67 Mb,and the GC content was 45.5%.In terms of evolutionary relationship,L.plantarums could be divided into 4 branches.L.plantarum CCFM8724 was closely related to L.plantarum VSCDJY5L5 and in the first branch,and was far from L.plantarum FGSYC25L4.Among the orthologous genes,L.plantarums shared 2232 core genes,and L.plantarum CCFM8724 had141 specific genes.The functions of these genes were mainly involved in the processes of carbohydrate and amino acid metabolism.GT111,AA1 and AA4 family genes only existed in L.plantarum CCFM8724,suggesting that L.plantarum CCFM8724 had unique carbohydrate synthesis and oxidation.These findings further lay a genetic foundation for the application and functional development of L.plantarum CCFM8724.