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Rabe A, Gesell Salazar M, Michalik S, Kocher T, Below H, Völker U, Welk A. Impact of different oral treatments on the composition of the supragingival plaque microbiome. J Oral Microbiol 2022; 14:2138251. [PMID: 36338832 PMCID: PMC9629129 DOI: 10.1080/20002297.2022.2138251] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Background Dental plaque consists of a diverse microbial community embedded in a complex structure of exopolysaccharides. Dental biofilms form a natural barrier against pathogens but lead to oral diseases in a dysbiotic state. Objective Using a metaproteome approach combined with a standard plaque-regrowth study, this pilot study examined the impact of different concentrations of lactoperoxidase (LPO) on early plaque formation, and active biological processes. Design Sixteen orally healthy subjects received four local treatments as a randomized single-blind study based on a cross-over design. Two lozenges containing components of the LPO-system in different concentrations were compared to a placebo and Listerine®. The newly formed dental plaque was analyzed by mass spectrometry (nLC-MS/MS). Results On average 1,916 metaproteins per sample were identified, which could be assigned to 116 genera and 1,316 protein functions. Listerine® reduced the number of metaproteins and their relative abundance, confirming the plaque inhibiting effect. The LPO-lozenges triggered mainly higher metaprotein abundances of early and secondary colonizers as well as bacteria associated with dental health but also periodontitis. Functional information indicated plaque biofilm growth. Conclusion In conclusion, the mechanisms on plaque biofilm formation of Listerine® and the LPO-system containing lozenges are different. In contrast to Listerine®, the lozenges led to a higher bacterial diversity.
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Affiliation(s)
- Alexander Rabe
- Interfaculty Institute for Genetics and Functional Genomics, Department of Functional Genomics, University Medicine Greifswald, Felix-Hausdorff-Str. 8, 17475Greifswald, Germany,CONTACT Alexander Rabe University Medicine Greifswald, Interfaculty Institute for Genetics and Functional Genomics, Department of Functional Genomics, Felix-Hausdorff-Str. 8, 17489Greifswald, Germany
| | - Manuela Gesell Salazar
- Interfaculty Institute for Genetics and Functional Genomics, Department of Functional Genomics, University Medicine Greifswald, Felix-Hausdorff-Str. 8, 17475Greifswald, Germany
| | - Stephan Michalik
- Interfaculty Institute for Genetics and Functional Genomics, Department of Functional Genomics, University Medicine Greifswald, Felix-Hausdorff-Str. 8, 17475Greifswald, Germany
| | - Thomas Kocher
- Center for Dentistry, Oral and Maxillofacial Medicine, Department of Restorative Dentistry, Periodontology, Endodontology, and Preventive and Pediatric Dentistry, Dental School of University Medicine Greifswald, Fleischmannstraße 42-44, 17489
| | - Harald Below
- Institute for Hygiene and Environmental Medicine, University Medicine Greifswald, Walter-Rathenau-Straße 49 A17475Greifswald, Germany
| | - Uwe Völker
- Interfaculty Institute for Genetics and Functional Genomics, Department of Functional Genomics, University Medicine Greifswald, Felix-Hausdorff-Str. 8, 17475Greifswald, Germany
| | - Alexander Welk
- Center for Dentistry, Oral and Maxillofacial Medicine, Department of Restorative Dentistry, Periodontology, Endodontology, and Preventive and Pediatric Dentistry, Dental School of University Medicine Greifswald, Fleischmannstraße 42-44, 17489
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2
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The salivary microbiome shows a high prevalence of core bacterial members yet variability across human populations. NPJ Biofilms Microbiomes 2022; 8:85. [PMID: 36266278 PMCID: PMC9584946 DOI: 10.1038/s41522-022-00343-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2022] [Accepted: 10/04/2022] [Indexed: 11/16/2022] Open
Abstract
Human saliva contains diverse bacterial communities, reflecting health status, dietary patterns and contributing to variability in the sensory perception of food. Many descriptions of the diversity of the salivary microbiome have focused on the changes induced by certain diseased states, but the commonalities and differences within healthy saliva have not been fully described. Here, we define and explore the core membership of the human salivary microbial community by collecting and re-analysing raw 16S rRNA amplicon sequencing data from 47 studies with 2206 saliva samples. We found 68 core bacterial taxa that were consistently detected. Differences induced by various host intrinsic and behaviour factors, including gender, age, geographic location, tobacco usage and alcohol consumption were evident. The core of the salivary microbiome was verified by collecting and analysing saliva in an independent study. These results suggest that the methods used can effectively define a core microbial community in human saliva. The core salivary microbiome demonstrated both stability and variability among populations. Geographic location was identified as the host factor that is most associated with the structure of salivary microbiota. The independent analysis confirmed the prevalence of the 68 core OTUs we defined from the global data and provides information about how bacterial taxa in saliva varies across human populations.
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3
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Clarke LJ, Suter L, King R, Bissett A, Bestley S, Deagle BE. Bacterial epibiont communities of panmictic Antarctic krill are spatially structured. Mol Ecol 2021; 30:1042-1052. [PMID: 33300251 DOI: 10.1111/mec.15771] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Revised: 10/09/2020] [Accepted: 12/03/2020] [Indexed: 12/28/2022]
Abstract
Antarctic krill (Euphausia superba) are amongst the most abundant animals on Earth, with a circumpolar distribution in the Southern Ocean. Genetic and genomic studies have failed to detect any population structure for the species, suggesting a single panmictic population. However, the hyper-abundance of krill slows the rate of genetic differentiation, masking potential underlying structure. Here we use high-throughput sequencing of bacterial 16S rRNA genes to show that krill bacterial epibiont communities exhibit spatial structuring, driven mainly by distance rather than environmental factors, especially for strongly krill-associated bacteria. Estimating the ecological processes driving bacterial community turnover indicated this was driven by bacterial dispersal limitation increasing with geographic distance. Furthermore, divergent epibiont communities generated from a single krill swarm split between aquarium tanks under near-identical conditions suggests physical isolation in itself can cause krill-associated bacterial communities to diverge. Our findings show that Antarctic krill-associated bacterial communities are geographically structured, in direct contrast with the lack of structure observed for krill genetic and genomic data.
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Affiliation(s)
- Laurence J Clarke
- Australian Antarctic Division, Kingston, Tas, Australia.,Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Tas, Australia.,Antarctic Climate & Ecosystems Cooperative Research Centre, University of Tasmania, Hobart, Tas, Australia
| | - Léonie Suter
- Australian Antarctic Division, Kingston, Tas, Australia
| | - Rob King
- Australian Antarctic Division, Kingston, Tas, Australia
| | - Andrew Bissett
- Commonwealth Scientific and Industrial Research Organisation, Hobart, Tas, Australia
| | - Sophie Bestley
- Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Tas, Australia
| | - Bruce E Deagle
- Australian Antarctic Division, Kingston, Tas, Australia.,Commonwealth Scientific and Industrial Research Organisation, Hobart, Tas, Australia
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4
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Weyrich LS. The evolutionary history of the human oral microbiota and its implications for modern health. Periodontol 2000 2020; 85:90-100. [PMID: 33226710 DOI: 10.1111/prd.12353] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Numerous biological and cultural factors influence the microbial communities (microbiota) that inhabit the human mouth, including diet, environment, hygiene, physiology, health status, genetics, and lifestyle. As oral microbiota can underpin oral and systemic diseases, tracing the evolutionary history of oral microbiota and the factors that shape its origins will unlock information to mitigate disease today. Despite this, the origins of many oral microbes remain unknown, and the key factors in the past that shaped our oral microbiota are only now emerging. High throughput DNA sequencing of oral microbiota using ancient DNA and comparative anthropological methodologies has been employed to investigate oral microbiota origins, revealing a complex, rich history. Here, I review the current literature on the factors that shaped and guided oral microbiota evolution, both in Europe and globally. In Europe, oral microbiota evolution was shaped by interactions with Neandertals, the adaptation of farming, widespread integration of industrialization, and postindustrial lifestyles that emerged after World War II. Globally, evidence for a multitude of different oral microbiota histories is emerging, likely supporting dissimilarities in modern oral health across discrete human populations. I highlight how these evolutionary changes are linked to the development of modern oral diseases and discuss the remaining factors that need to be addressed to improve this embryonic field of research. I argue that understanding the evolutionary history of our oral microbiota is necessary to identify new treatment and prevention options to improve oral and systemic health in the future.
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Affiliation(s)
- Laura S Weyrich
- Department of Anthropology and the Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, Pennsylvania, USA.,School of Biological Sciences, University of Adelaide, Adelaide, South Australia, Australia
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5
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Ramadugu K, Bhaumik D, Luo T, Gicquelais RE, Lee KH, Stafford EB, Marrs CF, Neiswanger K, McNeil DW, Marazita ML, Foxman B. Maternal Oral Health Influences Infant Salivary Microbiome. J Dent Res 2020; 100:58-65. [PMID: 32859139 DOI: 10.1177/0022034520947665] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Oral microbiomes vary in cariogenic potential; these differences may be established early in life. A major concern is whether mothers transmit cariogenic bacteria to their children. Here we characterize early salivary microbiome development and the potential associations of that development with route of delivery, breastfeeding, and mother's oral health, and we evaluate transmission of microbes between mother and child. We analyzed saliva and metadata from the Center for Oral Health Research in Appalachia. For this cohort study, we sequenced the V6 region of the 16S rRNA gene and used quantitative polymerase chain reaction to detect Streptococcus mitis, Streptococcus sobrinus, Streptococcus mutans, Streptococcus oralis, and Candida albicans in the saliva from mothers and their infants, collected at 2, 9, and 12 mo (Pennsylvania site) and 2, 12, and 24 mo (West Virginia site). Breastfed children had lower relative abundances of Prevotella and Veillonella. If mothers had decayed, missing, or filled teeth, children had greater abundances of Veillonella and Actinomyces. There was little evidence of maternal transmission of selected microbes. At 12 mo, children's microbiomes were more similar to other children's than to their mothers'. Infants' salivary microbiomes became more adult-like with age but still differed with mothers' microbiomes at 12 mo. There was little evidence supporting transmission of selected microbes from mothers to children, but risk of colonization was associated with tooth emergence. Children are likely to acquire cariogenic bacteria from a variety of sources, including foods and contact with other children and adults.
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Affiliation(s)
- K Ramadugu
- School of Public Health, University of Michigan, Ann Arbor, MI, USA
| | - D Bhaumik
- School of Public Health, University of Michigan, Ann Arbor, MI, USA
| | - T Luo
- School of Public Health, University of Michigan, Ann Arbor, MI, USA
| | - R E Gicquelais
- School of Public Health, University of Michigan, Ann Arbor, MI, USA
| | - K H Lee
- School of Public Health, University of Michigan, Ann Arbor, MI, USA
| | - E B Stafford
- School of Public Health, University of Michigan, Ann Arbor, MI, USA
| | - C F Marrs
- School of Public Health, University of Michigan, Ann Arbor, MI, USA
| | - K Neiswanger
- Center for Craniofacial and Dental Genetics, University of Pittsburgh, Pittsburgh, PA, USA
| | - D W McNeil
- Center for Oral Health Research in Appalachia, Department of Psychology, Department of Dental Practice and Rural Health, West Virginia University, Morgantown, WV, USA
| | - M L Marazita
- Center for Craniofacial and Dental Genetics, Department of Oral Biology, Department of Human Genetics, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA, USA
| | - B Foxman
- Center of Molecular and Clinical Epidemiology of Infectious Diseases, Department of Epidemiology, School of Public Health, University of Michigan, Ann Arbor, MI, USA
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6
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Ramadugu K, Blostein F, Bhaumik D, Jiang W, Davis E, Salzman E, Srinivasan U, Marrs CF, Neiswanger K, McNeil DW, Marazita ML, Foxman B. Co-occurrence of yeast, streptococci, dental decay, and gingivitis in the post-partum period: results of a longitudinal study. J Oral Microbiol 2020; 12:1746494. [PMID: 32363007 PMCID: PMC7178893 DOI: 10.1080/20002297.2020.1746494] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Revised: 03/10/2020] [Accepted: 03/16/2020] [Indexed: 12/30/2022] Open
Abstract
Objective: The interactions between yeast and streptococci species that lead to dental decay and gingivitis are poorly understood. Our study describes these associations among a cohort of 101 post-partum women enrolled in the Center for Oral Health Research in Appalachia, 2012–2013. Methods: All eligible women without dental caries were included (n = 21) and the remainder were randomly sampled to represent the total number of decayed, missing, and filled teeth (DMFT) at enrollment. We used amplicon sequencing and qPCR of saliva from 2, 6, 12 and 24 visits to determine microbiome composition. Results: Active decay and generalized gingivitis were strongly predictive of each other. Using adjusted marginal models, Candida albicans and Streptococcus mutans combined were associated with active decay (OR = 3.13; 95% CI 1.26, 7.75). However, C. albicans alone (OR = 2.33; 95% CI: 0.81, 6.75) was associated with generalized gingivitis, but S. mutans alone was not (OR = 0.55; 95% CI: 0.21, 1.44). Models including microbiome community state types (CSTs) showed CSTs positively associated with active decay were negatively associated with generalized gingivitis. Discussion: C. albicans is associated with active decay and generalized gingivitis, but whether one or both are present depends on the structure of the co-existing microbial community.
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Affiliation(s)
- Kirtana Ramadugu
- Center for Molecular and Clinical Epidemiology of Infectious Diseases, University of Michigan School of Public Health Department of Epidemiology, Ann Arbor, MI, USA
| | - Freida Blostein
- Center for Molecular and Clinical Epidemiology of Infectious Diseases, University of Michigan School of Public Health Department of Epidemiology, Ann Arbor, MI, USA
| | - Deesha Bhaumik
- Center for Molecular and Clinical Epidemiology of Infectious Diseases, University of Michigan School of Public Health Department of Epidemiology, Ann Arbor, MI, USA
| | - Wenwen Jiang
- Center for Molecular and Clinical Epidemiology of Infectious Diseases, University of Michigan School of Public Health Department of Epidemiology, Ann Arbor, MI, USA
| | - Elyse Davis
- Center for Molecular and Clinical Epidemiology of Infectious Diseases, University of Michigan School of Public Health Department of Epidemiology, Ann Arbor, MI, USA
| | - Elizabeth Salzman
- Center for Molecular and Clinical Epidemiology of Infectious Diseases, University of Michigan School of Public Health Department of Epidemiology, Ann Arbor, MI, USA
| | - Usha Srinivasan
- Center for Molecular and Clinical Epidemiology of Infectious Diseases, University of Michigan School of Public Health Department of Epidemiology, Ann Arbor, MI, USA
| | - Carl F Marrs
- Center for Molecular and Clinical Epidemiology of Infectious Diseases, University of Michigan School of Public Health Department of Epidemiology, Ann Arbor, MI, USA
| | - Katherine Neiswanger
- Center for Craniofacial and Dental Genetics, Department of Oral Biology, School of Dental Medicine, University of Pittsburgh, Pittsburgh, PA, USA.,Center for Oral Health Research in Appalachia, University of Pittsburgh, Pittsburgh, Pennsylvania, USA, and West Virginia University, Morgantown, West Virginia, USA
| | - Daniel W McNeil
- Center for Oral Health Research in Appalachia, University of Pittsburgh, Pittsburgh, Pennsylvania, USA, and West Virginia University, Morgantown, West Virginia, USA.,Departments of Psychology and Dental Practice & Rural Health, West Virginia University, Morgantown, WV, USA
| | - Mary L Marazita
- Center for Craniofacial and Dental Genetics, Department of Oral Biology, School of Dental Medicine, University of Pittsburgh, Pittsburgh, PA, USA.,Center for Oral Health Research in Appalachia, University of Pittsburgh, Pittsburgh, Pennsylvania, USA, and West Virginia University, Morgantown, West Virginia, USA.,Department of Human Genetics, Graduate School of Public Health; and Clinical and Translational Sciences Institute, School of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
| | - Betsy Foxman
- Center for Molecular and Clinical Epidemiology of Infectious Diseases, University of Michigan School of Public Health Department of Epidemiology, Ann Arbor, MI, USA.,Center for Oral Health Research in Appalachia, University of Pittsburgh, Pittsburgh, Pennsylvania, USA, and West Virginia University, Morgantown, West Virginia, USA.,Departments of Psychology and Dental Practice & Rural Health, West Virginia University, Morgantown, WV, USA
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7
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Sex-specific differences in the occurrence of Fusobacterium nucleatum subspecies and Fusobacterium periodonticum in the oral cavity. Oncotarget 2018; 9:20631-20639. [PMID: 29755677 PMCID: PMC5945502 DOI: 10.18632/oncotarget.25042] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Accepted: 03/22/2018] [Indexed: 01/01/2023] Open
Abstract
The periodontitis-associated species Fusobacterium nucleatum (FN) has been implicated in several extra-oral diseases, including preterm birth and colorectal cancer. Due to its genetic and phenotypic heterogeneity, FN is classified in four subspecies which may differ in their disease potential. Here we compared the prevalence of FN subspecies and the close relative F. periodonticum (FP) via 16S rRNA gene analysis in saliva from 100 healthy individuals (60 females, and 40 males) from eleven countries spanning five continents. By focusing on the most abundant sequence types (i.e. analysis of approximately ten clone sequences each) the average number of FN/FP subspecies per individual differed significantly between females and males, i.e. 2.93 versus 2.5, respectively (P = 0.043). FN subsp. fusiforme/vincentii was significantly more prevalent in females vs males, with 2.85 vs. 1.68 sequence reads per individual, respectively (P = 0.012). A significant age-related difference was observed in females but not in males, i.e. 2.6 subspecies on average in females ≤ 30 years vs. 3.2 in females > 30 (P = 0.0076). Given the link between FN and systemic disorders our findings highlight the need for microbial studies at the subspecies level to further characterize the role of periodontal pathogens in diseases that affect females and males differently, e.g. colorectal cancer.
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8
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Sarkar A, Stoneking M, Nandineni MR. Unraveling the human salivary microbiome diversity in Indian populations. PLoS One 2017; 12:e0184515. [PMID: 28886168 PMCID: PMC5590957 DOI: 10.1371/journal.pone.0184515] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2017] [Accepted: 08/27/2017] [Indexed: 12/21/2022] Open
Abstract
The importance of studying the salivary microbiome has been highlighted for its connection to health and disease and as a potential tool for supplementing human genetic diversity studies. While the salivary microbiome has been studied in various world populations, Indian populations have not been examined. We therefore analyzed microbiome diversity in saliva samples from 92 volunteers from eight different sampling locations in India by amplifying and sequencing variable regions (V1 and V2) of the bacterial 16S rRNA gene. The results showed immense bacterial richness in Indian populations; we identified 165 bacterial genera and 785 unique Operational Taxonomic Units (OTUs), with substantial sharing among the populations. There were small, but significant correlations in the abundance of bacterial genera in sampling locations from the same geographic region. Most of the core OTUs detected were also observed previously in other populations, but Solobacterium spp., Lachnoanaerobaculum spp. and Alloprevotella spp. were observed to be a component of the saliva microbiome unique to Indian populations. Importantly, nine bacterial genera were observed that were not listed in the Human Oral Microbiome Database (HOMD). These results highlight the importance of analyzing underrepresented populations like those of India.
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Affiliation(s)
- Anujit Sarkar
- Laboratory of Genomics and Profiling Applications, Centre for DNA Fingerprinting and Diagnostics (CDFD), Hyderabad, Telangana. India
- Graduate studies, Manipal University, Manipal. Karnataka, India
| | - Mark Stoneking
- Department of Evolutionary Genetics, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
| | - Madhusudan R. Nandineni
- Laboratory of Genomics and Profiling Applications, Centre for DNA Fingerprinting and Diagnostics (CDFD), Hyderabad, Telangana. India
- Laboratory of DNA Fingerprinting Services, Centre for DNA Fingerprinting and Diagnostics (CDFD), Hyderabad, Telangana. India
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9
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Schnorr SL, Sankaranarayanan K, Lewis CM, Warinner C. Insights into human evolution from ancient and contemporary microbiome studies. Curr Opin Genet Dev 2016; 41:14-26. [PMID: 27507098 DOI: 10.1016/j.gde.2016.07.003] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Revised: 07/01/2016] [Accepted: 07/04/2016] [Indexed: 12/11/2022]
Abstract
Over the past decade, human microbiome research has energized the study of human evolution through a complete shift in our understanding of what it means to be human. The microbiome plays a pivotal role in human biology, performing key functions in digestion, mood and behavior, development and immunity, and a range of acute and chronic diseases. It is therefore critical to understand its evolution and changing ecology through time. Here we review recent findings on the microbiota of diverse human populations, non-human primates, and past human populations and discuss the implications of this research in formulating a deeper evolutionary understanding of the human holobiont.
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Affiliation(s)
- Stephanie L Schnorr
- Department of Anthropology, University of Oklahoma, 455 W. Lindsey St., Norman, OK 73019, USA
| | | | - Cecil M Lewis
- Department of Anthropology, University of Oklahoma, 455 W. Lindsey St., Norman, OK 73019, USA
| | - Christina Warinner
- Department of Anthropology, University of Oklahoma, 455 W. Lindsey St., Norman, OK 73019, USA.
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10
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Horz HP. Archaeal Lineages within the Human Microbiome: Absent, Rare or Elusive? Life (Basel) 2015; 5:1333-45. [PMID: 25950865 PMCID: PMC4500141 DOI: 10.3390/life5021333] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2015] [Revised: 04/27/2015] [Accepted: 04/28/2015] [Indexed: 12/15/2022] Open
Abstract
Archaea are well-recognized components of the human microbiome. However, they appear to be drastically underrepresented compared to the high diversity of bacterial taxa which can be found on various human anatomic sites, such as the gastrointestinal environment, the oral cavity and the skin. As our “microbial” view of the human body, including the methodological concepts used to describe them, has been traditionally biased towards bacteria, the question arises whether our current knowledge reflects the actual ratio of archaea versus bacteria or whether we have failed so far to unravel the full diversity of human-associated archaea. This review article hypothesizes that distinct archaeal lineages within humans exist, which still await our detection. First, previously unrecognized taxa might be quite common but they have eluded conventional detection methods. Two recent prime examples are described that demonstrate that this might be the case for specific archaeal lineages. Second, some archaeal taxa might be overlooked because they are rare and/or in low abundance. Evidence for this exists for a broad range of phylogenetic lineages, however we currently do not know whether these sporadically appearing organisms are mere transients or important members of the so called “rare biosphere” with probably basic ecosystem functions. Lastly, evidence exists that different human populations harbor different archaeal taxa and/or the abundance and activity of shared archaeal taxa may differ and thus their impact on the overall microbiome. This research line is rather unexplored and warrants further investigation. While not recapitulating exhaustively all studies on archaeal diversity in humans, this review highlights pertinent recent findings that show that the choice of appropriate methodological approaches and the consideration of different human populations may lead to the detection of archaeal lineages previously not associated with humans. This in turn will help understand variations found in the overall microbiomes from different individuals and ultimately may lead to the emergence of novel concepts/mechanisms impacting human health.
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Affiliation(s)
- Hans-Peter Horz
- Division of Virology, Institute of Medical Microbiology, RWTH Aachen University Hospital, Pauwelsstrasse 30, 52057 Aachen, Germany.
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