Trichococcus shcherbakoviae subsp. psychrophilus subsp. nov., a psychrotolerant facultative anaerobe isolated from a cold spring.

A psychrotolerant facultative anaerobe, strain SKBGT, was isolated from the bottom sediments of the cold mineral spring Buxichen (Buryatia, Russia). Gram-positive non-motile cocci with a diameter of 1.75-2.5 µm were observed singly or in long chains. Cells grew in the temperature range from ̶ 5-35 °C. Growth was observed within the pH range of 7.0-9.5, with the optimum growth at pH 7.6 and at a NaCl concentration from 0-1.0 % (optimum 0.1 % (w/v)). Strain SKBGT was a chemoorganoheterotroph that used sugars and some organic acids as substrates. The predominant fatty acids in cell walls were С16:1ω9, С18:1ω9, and С16 : 0. The 16S rRNA gene sequence of strain SKBGT shared high similarity (>99 %) with those of the type strains of the genus Trichococcus. Digital DNA-DNA hybridization (dDDH) and average nucleotide identity (ANI) values between strain SKBGT and Trichococcus shcherbakoviae ArtT (=DSM 107162T=VKM B-3260T) were 70.1 and 95.4 %, respectively. The genomic DNA G+C content of strain SKBGT was 47.1 mol%. Compared with the type strain of T. shcherbakoviae, the new strain was characterized by a temperature optimum for growth (10 °C) significantly lower than that of T. shcherbakoviae DSM 107162T (20-30 °C). Based on phenotypic and genomic characteristics, the isolate SKBGT was classified as T. shcherbakoviae subsp. psychrophilus subsp. nov. The type strain is SKBGT (=VKM B-3241Т=JCM 33326T).

Alloiococcus otitidis, ¿patógeno exclusivo del oído medio? / Alloiococcus otitidis, exclusive pathogen of the middle ear?

La bronquitis bacteriana persistente (BBP) se define como tos húmeda de más de tres semanas de evolución, aislamiento de patógeno en cultivo de una muestra de líquido broncoalveolar y desaparición de la tos con tratamiento con amoxicilina y ácido clavulánico durante al menos dos semanas. Si bien han aumentado el número de casos descritos desde su descripción en 2006, sigue siendo una enfermedad infradiagnosticada a pesar de que el diagnóstico y tratamiento precoz previenen la progresión a formas más graves, que pueden llegar a ser irreversibles. En la literatura se describen múltiples agentes etiológicos, siendo los más frecuentes Haemophilus influenzae no tipable, Streptococcus pneumoniae y Moraxella catarrhalis. No obstante, no hay ningún caso descrito de Alloiococcus otitidis como agente causal de BBP. Este microorganismo se ha aislado principalmente en patología del oído medio

Persistent bacterial bronchitis (PBB) is defined by the presence of wet cough for longer than 3 weeks, isolation of the pathogen in bronchoalveolar cultures and resolution of the cough with treatment with amoxicillin and clavulanic acid for at least two weeks. Although the number of updated cases has increased since its description in 2006, it remains an underdiagnosed disease despite the fact that early diagnosis and treatment prevents the evolution to more serious forms which can become irreversible. Multiple etiologic agents are found in the literature, the most frequent are non-typable Haemophilus influenzae, Streptococcus pneumoniae and Moraxella catarrhalis. However, there is no reported case of Alloidococcus otitidis as the causative agent of PBB. This microorganism has been isolated mainly in middle ear pathology

Jeotgalibaca ciconiae sp. nov., isolated from the faeces of an Oriental stork.

A novel, Gram-stain-positive, non-spore-forming, facultatively anaerobic bacterium, designated strain H21T32T, was isolated from the faeces of an Oriental stork, Ciconia boyciana. Cells formed cocci grouped in pairs, tetrads or conglomerates, and colonies on solid medium were pale yellow. Strain H21T32T belonged to the genus Jeotgalibaca, family Carnobacteriaceae, order Lactobacillales and class Bacilli. The 16S rRNA gene sequences of the strain showed 97.06-97.34, 96.17-96.31 and 95.93-96.07 % similarity to the type strains of Jeotgalibaca arthritidis, J. porci and J. dankookensis, respectively. The strain grew at 10-37 °C (optimum temperature: 30 °C), with 0-7 % (w/v) NaCl (optimum salinity: 0.5 %) and at pH 7-9 (optimum pH: 8). The main cellular fatty acids were C16 : 1 ω9c, C18 : 1 ω9c and C16 : 0. The major polar lipids were diphosphatidylglycerol and phosphatidylglycerol. Respiratory quinones were not detected. Sugar components of the peptidoglycan were rhamnose, ribose and glucose. Amino acid components of the cell wall were l-alanine, d-glucose, l-lysine, glycine and aspartic acid. The DNA G+C content of the strain was 37.1 mol%. Average nucleotide identity between strain H21T32T and J. arthritidis CECT 9157T was 77.02 %, confirming that strain H21T32T represents a novel species of the genus Jeotgalibaca, for which the name Jeotgalibaca ciconiae sp. nov. is proposed. The type strain is H21T32T (=KCTC 33991T=JCM 33222T).

Trichococcus shcherbakoviae sp. nov., isolated from a laboratory-scale anaerobic EGSB bioreactor operated at low temperature.

A new species of the genus Trichococcus, strain Art1T, was isolated from a psychrotolerant syntrophic propionate-oxidizing consortium, obtained before from a low-temperature EGSB reactor fed with a mixture of VFAs (acetate, propionate and butyrate). The 16S rRNA gene sequence of strain Art1T was highly similar to those of other Trichococcus species (99.7-99.9 %) but digital DNA-DNA hybridization values were lower than those recommended for the delineation of a novel species, indicating that strain Art1T is a novel species of the genus Trichococcus. Cells of strain Art1T are non-motile cocci with a diameter of 0.5-2.0 µm and were observed singularly, in pairs, short chains and irregular conglomerates. Cells of Art1T stained Gram-positive and produced extracellular polymeric substances . Growth was optimal at pH 6-7.5 and cells could grow in a temperature range of from -2 to 30 °C (optimum 25-30 °C). Strain Art1T can degrade several carbohydrates, and the main products from glucose fermentation are lactate, acetate, formate and ethanol. The genomic DNA G+C content of strain Art1T is 46.7 %. The major components of the cellular fatty acids are C16 : 1 ω9c, C16 : 0 and C18 : 1 ω9c. Based on genomic and physiological characteristics of strain Art1T, a new species of the genus Trichococcus, Trichococcusshcherbakoviae, is proposed. The type strain of Trichococcusshcherbakoviae is Art1T (=DSM 107162T = VKM B-3260T).

Chronic Rhinosinusitis: Potential Role of Microbial Dysbiosis and Recommendations for Sampling Sites.

Chronic rhinosinusitis (CRS) is an inflammatory condition that affects up to 12% of the human population in developed countries. Previous studies examining the potential role of the sinus bacterial microbiota within CRS infections have found inconsistent results, possibly because of inconsistencies in sampling strategies. The aim of this study was to determine whether the sinus microbiome is altered in CRS and additionally if the middle meatus is a suitable representative site for sampling the sinus microbiome. Swab samples were collected from 12 healthy controls and 21 CRS patients, including all eight sinuses for CRS patients and between one and five sinuses for control subjects. The left and right middle meatus and nostril swabs were also collected. Significant differences in the sinus microbiomes between CRS and control samples were revealed using high-throughput 16S rRNA gene sequencing. The genus Escherichia was over-represented in CRS sinuses, and associations between control patients and Corynebacterium and Dolosigranulum were also identified. Comparisons of the middle meatuses between groups did not reflect these differences, and the abundance of the genus Escherichia was significantly lower at this location. Additionally, intra-patient variation was lower between sinuses than between sinus and middle meatus, which together with the above results suggests that the middle meatus is not an effective representative sampling site.

Characterization of Trichococcus paludicola sp. nov. and Trichococcus alkaliphilus sp. nov., isolated from a high-elevation wetland, by phenotypic and genomic analyses.

Two psychrotolerant facultative anaerobes, strains B7-2T and B5T, were isolated from the Zoige Wetland on the Qinghai-Tibetan Plateau. The 16S rRNA gene sequences of strains B7-2T and B5T shared high similarity (>99 %) with those of the type strains of the genus Trichococcus, while their digital DNA-DNA hybridization values with each other (49 %) and with the reference type strains (48-23 %) were lower than 70 %, which suggest that they represent two novel species of the genus Trichococcus. Cells of strains B7-2T and B5T were immotile cocci, grew in the temperature range of 4-37 °C (optimum 25 °C) and were alkaliphilic with optimum growth at pH 9.0. The major components of the cellular fatty acids were C16 : 0, anteiso-C17 : 0 and C18 : 0 for strain B7-2T, and C16 : 0, anteiso-C17 : 0, C18 : 1ω9c and C18 : 0 for strain B5T. The genomic DNA G+C contents were 46.0 and 46.7 mol% for strains B7-2T and B5T, respectively. Based on physiological and genomic characteristics, it is suggested that strains B7-2T and B5T represent two novel species within the genus Trichococcus, for which the names Trichococcus paludicola sp. nov. and Trichococcus alkaliphilus sp. nov. are proposed. The type strains are B7-2T (=DSM 104691T=KCTC 33886T) and B5T (=DSM 104692T=KCTC 33885T), respectively.

Jeotgalibaca porci sp. nov. and Jeotgalibaca arthritidis sp. nov., isolated from pigs, and emended description of the genus Jeotgalibaca.

Biochemical and molecular genetic studies were performed on two novel Gram-stain-positive, catalase-negative, coccus-shaped organisms isolated from liquid joint samples of two pigs. The micro-organisms were not identified as members of a recognized species based on results of cellular, morphological and biochemical tests. 16S rRNA gene sequence comparison studies allowed their identification as members of the genus Jeotgalibaca, but the organisms were different to Jeotgalibaca dankookensis, the single species of the genus. The two micro-organisms shared 96.3 and 96.9 % 16S rRNA gene sequence similarity values with their nearest phylogenetic relative, J. dankookensis. The novel bacterial isolates were distinguished from J. dankookensis using biochemical tests. Based on both phenotypic and phylogenetic findings, it is proposed that the unknown bacteria be classified as representatives of two novel species of the genus Jeotgalibaca, Jeotgalibaca porci sp. nov. and Jeotgalibaca arthritidis sp. nov. The type strain of Jeotgalibaca porcisp. nov. is 1804-02T (=CECT 9156T=CCUG 69148T) and that of Jeotgalibaca arthritidissp. nov. is 1805-02T (=CECT 9157T=CCUG 69147T).

Description of Trichococcus ilyis sp. nov. by combined physiological and in silico genome hybridization analyses.

Species of the genus Trichococcus share high similarity of their 16S rRNA gene sequences (>99 %). Digital DNA-DNA hybridization values (dDDH) among type strains of all described species of the genus Trichococcus (T. flocculiformis DSM 2094T, T. pasteurii DSM 2381T, T. collinsii DSM 14526T, T. palustris DSM 9172T, and T. patagoniensisDSM 18806T) indicated that Trichococcus sp. strain R210T represents a novel species of the genus Trichococcus. The dDDH values showed a low DNA relatedness between strain R210T and all other species of the genus Trichococcus (23-32%). Cells of strain R210T were motile, slightly curved rods, 0.63-1.40×0.48-0.90 µm and stained Gram-positive. Growth was optimal at pH 7.8 and at temperature of 30 °C. Strain R210T could utilize several carbohydrates, and the main products from glucose fermentation were lactate, acetate, formate and ethanol. The genomic DNA G+C content of strain R210T was 47.9 mol%. Based on morphological, physiological and biochemical characteristics along with measured dDDH values for all species of the genus Trichococcus, it is suggested that strain R210T represents a novel species within the genus Trichococcus, for which the name Trichococcus ilyis sp. nov. is proposed. The type strain is R210T (=DSM 22150T=JCM 31247T).

Antimicrobial Susceptibilities of Abiotrophia defectiva, Granulicatella adiacens, and Granulicatella elegans.

Nutritionally variant streptococci (NVS) are fastidious Gram-positive cocci comprised of the species Abiotrophia defectiva, Granulicatella adiacens, and Granulicatella elegans. NVS are an important cause of bacteremia and infective endocarditis (IE) associated with significant morbidity and mortality. Antimicrobial susceptibility testing (AST) was performed for 14 antimicrobials using the broth microdilution MIC method described in the Clinical and Laboratory Standards Institute (CLSI) M45 guideline. A total of 132 clinical NVS blood isolates collected from 2008 to 2014 were tested. Species level identification of NVS isolates was achieved by 16S rRNA gene sequencing and/or matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). Ninety isolates were identified as G. adiacens, 37 as A. defectiva, and 5 as G. elegans. All isolates were susceptible to vancomycin (MIC90 = 1 µg/ml), and none displayed high-level resistance to aminoglycosides. G. adiacens was considerably more susceptible to penicillin than A. defectiva (38.9% versus 10.8% of isolates susceptible) but was less susceptible to cephalosporins than was A. defectiva (43.3% versus 100% of isolates susceptible to ceftriaxone). Several isolates were resistant to levofloxacin (6%), erythromycin (51%), and clindamycin (10%). The MIC90 for daptomycin was ≥ 4 µg/ml for G. adiacens and A. defectiva. G. elegans isolates were 100% susceptible to all antimicrobials tested, with the exception of erythromycin, to which only 20% were susceptible. This study provides antimicrobial susceptibility data for a recent collection of NVS and demonstrates important NVS species-related differences with respect to susceptibility to penicillin, cephalosporins, carbapenems, and daptomycin. Species-level identification of NVS organisms when susceptibility testing is not readily available may aid in treatment decisions.

Jeotgalibaca dankookensis gen. nov., sp. nov., a member of the family Carnobacteriaceae, isolated from seujeot (Korean traditional food).

A novel, Gram-stain-positive bacterium, designated strain EX-07T, was isolated from seujeot (Korean traditional food). The strain was aerobic, halotolerant and non-motile; it formed cocci that grouped into tetrads and sarcinae or formed irregular conglomerates. Growth occurred at pH 7-9, at 10-37 °C and with up to 9% NaCl. Isolate EX-07T was catalase- and oxidase-negative and used sugars and organic acids as carbon sources. The 16S rRNA gene sequence of the novel strain showed 94.2-94.5% similarity with the type strains of Trichococcus pasteurii, Trichococcus patagoniensis, Trichococcus collinsii, Trichococcus flocculiformis and Trichococcus palustris and only 92.2% with representatives of the genera Bavariicoccus, Carnobacterium and Granulicatella. Sequence similarities based on the groEL gene ranged from 81.3 to 82.8% between the novel isolate and the type strains of all species of the genus Trichococcus, and only 74.2 and 75.3% with type strains of members of the genera Bavariicoccus and Granulicatella, respectively. The G+C content of the genomic DNA was 39.6 mol%. The predominant fatty acids were C16:1ω9c, C18:1ω9c, C16:0 and C14:0. The polar lipid profile was very complex and included phosphatidylethanolamine and several unidentified aminolipids, glycolipids and phospholipids. Based on the genotypic and phenotypic results obtained in this study, it is proposed that isolate EX-07T represents a novel species of a new genus in the family Carnobacteriaceae for which the name Jeotgalibaca dankookensis gen. nov., sp. nov. is proposed. The type strain of Jeotgalibaca dankookensis is EX-07T (=KCCM 90229T=JCM 19215T).

Characterization of oral bacterial diversity of irradiated patients by high-throughput sequencing.

The objective of this study was to investigate the compositional profiles and microbial shifts of oral microbiota during head-and-neck radiotherapy. Bioinformatic analysis based on 16S rRNA gene pyrosequencing was performed to assess the diversity and variation of oral microbiota of irradiated patients. Eight patients with head and neck cancers were involved in this study. For each patient, supragingival plaque samples were collected at seven time points before and during radiotherapy. A total of 147,232 qualified sequences were obtained through pyrosequencing and bioinformatic analysis, representing 3,460 species level operational taxonomic units (OTUs) and 140 genus level taxa. Temporal variations were observed across different time points and supported by cluster analysis based on weighted UniFrac metrics. Moreover, the low evenness of oral microbial communities in relative abundance was revealed by Lorenz curves. This study contributed to a better understanding of the detailed characterization of oral bacterial diversity of irradiated patients.

Bacterial diversity in the saliva of patients with different oral hygiene indexes.

The objective of the present study was to evaluate the bacterial diversity in the saliva of patients with different oral hygiene indexes using of two 16S rRNA gene libraries. Each library was composed of samples from patients with different averages of the differentiated Silness-Löe biofilm index: the first library (A) with an index between 1.0 and 3.0 (considered a high index) and the second library (B) between 0 and 0.5 (considered a low index). Saliva DNA was extracted and the 16S rRNA gene was amplified and cloned. The obtained sequences were compared with those stored at NCBI and RDP GenBank. The saliva of patients with high index presented five known genera - Streptococcus, Granulicatella, Gemella, Veillonella and Peptostreptococcus - and 33.3% of nonculturable bacteria grouped into 23 operational taxonomic units (OTUs). The saliva of patients with low index differed significantly from the first library (p=0.000) and was composed of 42 OTUs distributed into 11 known genera - Streptococcus, Granulicatella, Gemella, Veillonella, Oribacterium, Haemophilus, Escherichia, Neisseria, Prevotella, Capnocytophaga, Actinomyces - including 24.87% of nonculturable bacteria. It was possible to conclude that there is greater bacterial diversity in the saliva of patients with low dental plaque in relation to patients with high dental plaque.

Endocarditis caused by nutritionally variant streptococci: a case report and literature review.

Infective endocarditis (IE) due to Abiotrophia and Granulicatella species, previously referred to as nutritionally variant streptococci (NVS), occurs rarely and is often associated with negative blood cultures. Rates of treatment failure, infection relapse and mortality are higher than those of endocarditis caused by other viridans streptococci. We report a case of endocarditis caused by Granulicatella adiacens in a young man with no risk factors, who was successfully treated with surgery and combination antimicrobial chemotherapy, and provide a literature review of endocarditis attributable to these rare species of fastidious gram-positive cocci which have proven exceedingly difficult to treat, with high rates of relapse and therapeutic failure despite in vitro effective antibiotic treatment regimens. Analysis of literature revealed a high prevalence (61%) of valvular heart predisposing conditions associated with endocarditis caused by NVS, such as congenital valvular heart disease or heart valve prosthesis. On the other hand, 39% of cases showed no evidence of risk factors. Combination antimicrobial chemotherapy with penicillin and gentamicin represents the antimicrobial treatment of choice in the management of patients with IE attributable to NVS. Heart valve replacement surgery should be considered in cases of hemodynamic derangement due to significant valve destruction.

Acinetobacter, Aeromonas and Trichococcus populations dominate the microbial community within urban sewer infrastructure.

We evaluated the population structure and temporal dynamics of the dominant community members within sewage influent from two wastewater treatment plants (WWTPs) in Milwaukee, WI. We generated > 1.1 M bacterial pyrotag sequences from the V6 hypervariable region of 16S rRNA genes from 38 influent samples and two samples taken upstream in the sanitary sewer system. Only a small fraction of pyrotags from influent samples (∼ 15%) matched sequences from human faecal samples. The faecal components of the sewage samples included enriched pyrotag populations from Lactococcus and Enterobacteriaceae relative to their fractional representation in human faecal samples. In contrast to the large number of distinct pyrotags that represent faecal bacteria such as Lachnospiraceae and Bacteroides, only one or two unique V6 sequences represented Acinetobacter, Aeromonas and Trichococcus, which collectively account for nearly 35% of the total sewage community. Two dominant Acinetobacter V6 pyrotags (designated Acineto tag 1 and Acineto tag 2) fluctuated inversely with a seasonal pattern over a 3-year period, suggesting two distinct Acinetobacter populations respond differently to ecological forcings in the system. A single nucleotide change in the V6 pyrotags accounted for the difference in these populations and corresponded to two phylogenetically distinct clades based on full-length sequences. Analysis of wavelet functions, derived from a mathematical model of temporal fluctuations, demonstrated that other abundant sewer associated populations including Trichococcus and Aeromonas had temporal patterns similar to either Acineto tag 1 or Acineto tag 2. Populations with related temporal fluctuations were found to significantly correlate with the same WWTP variables (5-day BOD, flow, ammonia, total phosphorous and suspended solids). These findings illustrate that small differences in V6 sequences can represent phylogenetically and ecologically distinct taxa. This work provides insight into microbial community composition and dynamics within the defined environment of urban sewer infrastructure.

1,3-Propanediol production from glycerol by a newly isolated Trichococcus strain.

A coccal bacterium (strain ES5) was isolated from methanogenic bioreactor sludge with glycerol as the sole energy and carbon source. Strain ES5 fermented glycerol to 1,3-propanediol as main product, and lactate, acetate and formate as minor products. The strain was phylogenetically closely related to Trichococcus flocculiformis; the rRNA gene sequence similarity was 99%. However, strain ES5 does not show the typical growth in chains of T. flocculiformis. Moreover, T. flocculiformis does not ferment glycerol. Strain ES5 used a variety of sugars for growth. With these substrates, lactate, acetate and formate were the main products, while 1,3-propanediol was not formed. The optimum growth temperature of strain ES5 ranges from 30-37°C, but like several other Trichoccoccus strains, strain ES5 is able to grow at low temperature (< 10°C). Therefore, strain ES5 may be an appropriate catalyst for the biotechnological production of 1,3-propanediol from glycerol at low ambient temperature.

The subgingival microbiota of Papillon-Lefèvre syndrome.

BACKGROUND: There is little information about the microbiologic profiles of periodontal lesions in Papillon-Lefèvre syndrome (PLS) and the significance of bacteria in the pathogenesis of periodontitis in these patients. This comprehensive analysis of the subgingival microbiota in patients with PLS used 16S ribosomal RNA (rRNA) clonal analysis and the 16S rRNA-based Human Oral Microbe Identification Microarray (HOMIM). METHODS: Thirteen patients with PLS from seven unrelated families volunteered for this microbiologic study. Subgingival plaque was collected with sterile paper points from multiple sites with ≥5 mm probing depth, and whole genomic DNA was extracted. The 16S rRNA genes were amplified, cloned, and sequenced. The samples were then probed for ≈300 predominant oral bacterial species using the HOMIM. RESULTS: The most commonly detected phylotypes in the clonal analysis were Gemella morbillorum, Gemella haemolysans, Granulicatella adiacens, Lachnospiraceae OT 100 (EI074), Parvimonas micra, Selenomonas noxia, and Veillonella parvula. As a group, streptococci were commonly detected in these individuals. In the HOMIM analysis, a total of 170 bacterial species/phylotypes were detected, with a range of 40 to 80 species per patient with PLS. Of these, 12 bacterial species were detected in medium to high levels in ≥50% of the individuals. The high-frequency strains were clustered into eight groups: Aggregatibacter actinomycetemcomitans, Campylobacter spp., Capnocytophaga granulosa, G. morbillorum, P. micra, Porphyromonas endodontalis, Streptococcus spp., and Tannerella forsythia. CONCLUSIONS: The subgingival microbiota in PLS is diverse. Periodontal pathogens commonly associated with chronic and aggressive periodontitis and opportunistic pathogens may be associated with the development of severe periodontitis in patients with PLS.

Bacterial diversity in the saliva of patients with different oral hygiene indexes

The objective of the present study was to evaluate the bacterial diversity in the saliva of patients with different oral hygiene indexes using of two 16S rRNA gene libraries. Each library was composed of samples from patients with different averages of the differentiated Silness-Löe biofilm index: the first library (A) with an index between 1.0 and 3.0 (considered a high index) and the second library (B) between 0 and 0.5 (considered a low index). Saliva DNA was extracted and the 16S rRNA gene was amplified and cloned. The obtained sequences were compared with those stored at NCBI and RDP GenBank. The saliva of patients with high index presented five known genera - Streptococcus, Granulicatella, Gemella, Veillonella and Peptostreptococcus - and 33.3% of nonculturable bacteria grouped into 23 operational taxonomic units (OTUs). The saliva of patients with low index differed significantly from the first library (p=0.000) and was composed of 42 OTUs distributed into 11 known genera - Streptococcus, Granulicatella, Gemella, Veillonella, Oribacterium, Haemophilus, Escherichia, Neisseria, Prevotella, Capnocytophaga, Actinomyces - including 24.87% of nonculturable bacteria. It was possible to conclude that there is greater bacterial diversity in the saliva of patients with low dental plaque in relation to patients with high dental plaque.

O objetivo do presente estudo foi avaliar a diversidade bacteriana da saliva de pacientes com diferentes índices de higiene bucal através da construção de duas bibliotecas do gene 16S rRNA. Cada biblioteca foi composta por amostras de saliva de pacientes com índice de biofilme dental de Silness-Löe diferenciado, sendo a primeira (A) com índice de 1,0 a 3,0 (denominada de alto índice) e a segunda (B), entre 0 a 0,5 (denominada de baixo índice). O DNA da saliva foi extraído e o gene 16S rRNA foi amplificado, clonado e sequenciado. As sequências obtidas foram comparadas com aquelas armazenadas no GenBank do NCBI e RDP. A saliva de pacientes com alto índice de biofilme dental apresentou cinco gêneros conhecidos: Streptococcus, Granulicatella, Gemella, Veillonella e Peptostreptococcus e 33,3% de bactérias não-cultivadas, agrupados em 23 unidades taxonômicas operacionais (UTOs). A saliva de pacientes com baixo índice de biofilme dental, foi diferente significativamente da primeira (p=0,000) e foi composta de 42 UTOs, distribuídas em 11 gêneros conhecidos: Streptococcus, Granulicatella, Gemella, Veillonella, Oribacterium, Haemophilus, Escherichia, Neisseria, Prevotella, Capnocytophaga, Actinomyces, além de 24,87% de bactérias não-cultivadas. Pode-se concluir que existe maior diversidade bacteriana na saliva de pacientes com baixo índice de biofilme dental em relação a pacientes com alto índice de biofilme dental.