Diversity and Morphology of Members of the Phylum “ Synergistetes ” in Periodontal Health and Disease

Abstract

Members of the phylum "Synergistetes" have frequently been detected in the human oral cavity at sites of dental disease, but they have rarely been detected in studies of oral health. Only two oral "Synergistetes" taxa are cultivable. The aims of this study were to investigate the diversity of "Synergistetes" in the oral cavity, to establish whether "Synergistetes" taxa are more strongly associated with periodontitis than with oral health, and to visualize unculturable "Synergistetes" in situ. Sixty samples (saliva, dental plaque, and mucosal swabs) were collected from five subjects with periodontitis and five periodontally healthy controls. Using phylumspecific 16S rRNA gene primers, "Synergistetes" were identified by PCR, cloning, and sequencing of 48 clones per PCR-positive sample. Subgingival plaque samples were labeled with probes targeting rRNA of unculturable oral "Synergistetes" using fluorescent in situ hybridization (FISH). Analysis of 1,664 clones revealed 12 "Synergistetes" operational taxonomic units (OTUs) at the 99% sequence identity level, 5 of which were novel. "Synergistetes" OTU 4.2 was found in significantly more subjects with periodontitis than controls (P ‫؍‬ 0.048) and was more abundant in subgingival plaque at diseased sites than at healthy sites in subjects with periodontitis (P ‫؍‬ 0.019) or controls (P ‫؍‬ 0.019). FISH analysis revealed that unculturable oral "Synergistetes" cells were large curved bacilli. The human oral cavity harbors a diverse population of "Synergistetes." "Synergistetes" OTU 4.2 is associated with periodontitis and may have a pathogenic role.Periodontitis leads to the destruction of the tissues supporting the teeth and results from an inappropriate inflammatory response in susceptible individuals provoked by members of the normal oral microbiota (17). This disease results in loss of the attachment between the periodontium and the teeth, along with the formation of pockets which become heavily colonized with anaerobic bacteria, many of which possess virulence factors that can cause further damage to the host (21). The bacterial community found below the gum line, subgingival plaque, is extremely diverse, particularly in individuals with periodontitis, and over 400 species are estimated to inhabit the disease-associated periodontal ecosystem (29).The candidate phylum "Synergistetes" (16) includes a wide variety of genera, including Aminobacterium, Aminomonas, Aminiphilus, Anaerobaculum, Cloacibacillus, Dethiosulfovibrio, Jonquetella, Pyramidobacter, Synergistes, Thermanaerovibrio, and Thermovirga (8,43). "Synergistetes" are widely distributed in the environment, form part of the normal microbiota of animals (10), and have also been isolated from a variety of sites in humans, including the oral cavity. "Synergistetes" have been detected in subgingival plaque associated with diseased sites in periodontitis patients (7,13,15,(18)(19)(20)29), in root canals and pus from abscesses in patients with endodontic infections (28,31,32,36,37,44), and in dental caries (27,30)....

Dysbiosis and Alterations in Predicted Functions of the Subgingival Microbiome in Chronic Periodontitis

“…This organism encodes several virulence factors, which may play a role in the pathogenesis of periodontal disease by enabling the organism to persist in periodontal pockets (50). Members of the phylum Synergistetes, a newly recognized phylum of Gram-negative anaerobic bacteria, were recently implicated in periodontal disease (51).…”

Subgingival Biofilm Structure

“…The parallel-orientated cells have been identified as members of the Synergistetes phylum ( fig. 4) [23,31], and represent a lineage composed of taxa that for the most part are not yet cultivable. Opposing the Synergistetes in this outermost part of the adhering biofilm, polymorphonuclear neutrophils can be observed by light, electron and epifluorescence microscopy ( fig.…”

Identification of Synergistetes in endodontic infections

“…Considerable work on the role of Synergistetes has been made in the field of periodontal infections. They are detected more frequently and more abundantly in subgingival plaque from periodontitis-affected than healthy sites [2], or in the saliva of patients with periodontitis, compared to healthy individuals [6].…”

“…They are found in several microenvironments and constitute part of the human microbiota in health and disease [1][2][3][4], including the oral microbiota [5].…”

“…Phylogenetically, the oral Synergistetes are divided principally into clusters, namely cluster A and cluster B [2,3]. Considerable work on the role of Synergistetes has been made in the field of periodontal infections.…”