Abstract Rampant caries is identified by rapid onset, severe decay affecting multiple surfaces, and early pulp infection. This case–control study was conducted to investigate the disparities in oral microbiota between children affected by rampant caries and their caries-free counterparts. A total of 88 preschool children, with matched distribution of sex and age in both the case and control groups, participated in this study. Children’s oral health–related behaviors were reported by parents, salivary pH levels were assessed using a portable pen-type pH meter, and supragingival dental plaque was analyzed by 16S rRNA gene sequencing. Children with rampant caries exhibited lower salivary pH levels, poorer toothbrushing habits, and more frequent consumption of sugary snacks. Veillonella , enriched in caries-free children, showed a positive correlation with salivary pH levels and a negative correlation with candy consumption. Conversely, Fusobacterium and Neisseria , more abundant in children with rampant caries, positively correlated with the frequency of candy consumption. Furthermore, Streptococcus mutans , Porphyromonas gingivalis , and Bacteroides acidifaciens were identified as potential oral microbiome markers for differentiating preschoolers with rampant caries from their caries-free peers. B. acidifaciens , typically found in the gut, has been rarely reported in the field of oral health. More well-designed cohort studies are recommended to elucidate the mechanisms through which gut microbiota influences rampant caries in pediatric patients and offer insights into effective strategies for caries management in young children. Key points • Lower salivary pH levels in children with rampant caries. • Biomarkers for predicting rampant caries. • Impact of oral health–related behaviors on oral microbiota.
A Gram-stain-positive, yellow-pigmented, catalase-positive and oxidase-negative, strictly aerobic actinobacterium, designated strain YIM 131853T, was isolated from lichen collected from the South Bank of the Baltic Sea. The novel strain was non-spore-forming, short rod-shaped and motile with a single polar flagellum. The strain could grow at 4-37 °C (optimum, 28 °C), at pH 4.0-12.0 (pH 6.0) and at 0-3 % (w/v) NaCl (1 %). The DNA G+C content of strain YIM 131853T based on the draft genome sequence was 68.3 mol%. Predominant cellular fatty acids (>10 %) were identified as anteiso-C15 : 0, anteiso-C17 : 0 and iso-C16 : 0. The polar lipid profile included diphosphatidylglycerol, dimannosyldiacylglycerol, three unknown glycolipids, two unknown phospholipids and one unknown lipid. Strain YIM 131853T had 2,4-diaminobutyric acid as the diagnostic cell-wall diamino acid, galactose and glucose as whole-cell sugars, and MK-10, MK-14, MK-13 and MK-12 as the major menaquinones. Although strain YIM 131853T exhibited a highest 16S rRNA gene sequence similarity (96.6 %) to Amnibacterium kyonggiense NBRC 109360T, phylogenetic analysis based on 16S rRNA gene sequences indicated that the strain formed a tight lineage with Naasia aerilata NBRC 108725T (96.5 % 16S rRNA gene sequence similarity), which was the only species of genus Naasia. Based on the results of phenotypic, chemotaxonomic and phylogenetic analyses, strain YIM 131853T should belong to the genus Naasia and represents a novel species of the genus Naasia, for which the name Naasia lichenicola sp. nov. is proposed. The type strain is YIM 131853T (=CGMCC 4.7565T=NBRC 113605T).
A Gram-strain positive, mycelium-forming actinomycete, YIM 121212T, was isolated from an alkaline soil sample collected in Yunnan province, PR China. Classification using a polyphasic approach indicated that YIM 121212T represents a member of the genus Prauserella, and is closely related to Prauserella coralliicola SCSIO 11529T (99.31 %), Prauserella endophytica SP28S-3T (99.17 %), Prauserella soli 12-833T (97.43 %), Prauserella oleivorans RIPIT (97.03 %), Prauserella marina MS498T (96.74 %), Prauserella rugosa DSM 43194T (96.54 %) and Prauserella muralis 05-Be-005T (95.92 %). Average nucleotide identity values (ANI) of YIM 121212T to P. coralliicola DSM 45821T and P. endophytica CGMCC 4.7182T were 93.1 and 92.8 %, respectively, which were lower than the threshold of 95 %. The digital DNA-DNA hybridization (dDDH) values between YIM 121212T and these two species were 50.8 and 49.9 %, respectively and thus were also well below the cut off value (>70 %) for species delineation. The DNA G+C content of YIM 121212T is 70.8 mol%. Major fatty acids are iso-C16 : 0, iso-C16 : 1H, C16 : 1ω7c/iso-C15 : 0 2OH, C17 : 1ω6c, and C17 : 1ω8c. The predominant menaquinone is MK-9(H4). The polar lipid profile consists of diphosphatidylglycerol (DPG), phosphatidylglycerol (PG), phosphatidylethanolamine (PE), phosphatidylmethylethanolamine (PME), phosphatidylinositol (PI), and phosphatidylinositol mannoside (PIM). The draft genomes were further analyzed for the presence of secondary metabolite biosynthesis (SMB) gene clusters. On the basis of the above observations, YIM121212T can be distinguished from closely related species belonging to the genus Prauserella. Thus, YIM121212T represents a novel species of the genus Prauserella, for which the name Prauserellaflavalba sp. nov. is proposed. The type strain is YIM121212T (=CCTCC AA 2013011T=DSM 45973T).
Bacteria-host interaction is a common, relevant, and intriguing biological phenomena. The host reacts actively or passively to the bacteria themselves, their products, debris, and so on, through various defense systems containing the immune system, the bacteria communicate with the local or distal tissues of the host via their own surface antigens, secreted products, nucleic acids, etc., resulting in relationships of attack and defense, adaptation, symbiosis, and even collaboration. The significance of bacterial membrane vesicles (MVs) as a powerful vehicle for the crosstalk mechanism between the two is growing. In the recent decade, the emergence of MVs in microbial interactions and a variety of bacterial infections, with multiple adhesions to host tissues, cell invasion and evasion of host defense mechanisms, have brought MVs to the forefront of bacterial pathogenesis research. Whereas MVs are a complex combination of molecules not yet fully understood, research into its effects, targeting and pathogenic components will advance its understanding and utilization. This review will summarize structural, extraction and penetration information on several classes of MVs and emphasize the role of MVs in transport and immune response activation. Finally, the potential of MVs as a therapeutic method will be highlighted, as will future research prospects.
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