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Giacomini JJ, Torres-Morales J, Tang J, Dewhirst FE, Borisy GG, Mark Welch JL. Spatial ecology of Haemophilus and Aggregatibacter in the human oral cavity. Microbiol Spectr 2024; 12:e0401723. [PMID: 38488280 PMCID: PMC10986600 DOI: 10.1128/spectrum.04017-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2023] [Accepted: 01/26/2024] [Indexed: 04/06/2024] Open
Abstract
Haemophilus and Aggregatibacter are two of the most common bacterial genera in the human oral cavity, encompassing both commensals and pathogens of substantial ecological and medical significance. In this study, we conducted a metapangenomic analysis of oral Haemophilus and Aggregatibacter species to uncover genomic diversity, phylogenetic relationships, and habitat specialization within the human oral cavity. Using three metrics-pangenomic gene content, phylogenomics, and average nucleotide identity (ANI)-we first identified distinct species and sub-species groups among these genera. Mapping of metagenomic reads then revealed clear patterns of habitat specialization, such as Aggregatibacter species predominantly in dental plaque, a distinctive Haemophilus parainfluenzae sub-species group on the tongue dorsum, and H. sp. HMT-036 predominantly in keratinized gingiva and buccal mucosa. In addition, we found that supragingival plaque samples contained predominantly only one out of the three taxa, H. parainfluenzae, Aggregatibacter aphrophilus, and A. sp. HMT-458, suggesting independent niches or a competitive relationship. Functional analyses revealed the presence of key metabolic genes, such as oxaloacetate decarboxylase, correlated with habitat specialization, suggesting metabolic versatility as a driving force. Additionally, heme synthesis distinguishes H. sp. HMT-036 from closely related Haemophilus haemolyticus, suggesting that the availability of micronutrients, particularly iron, was important in the evolutionary ecology of these species. Overall, our study exemplifies the power of metapangenomics to identify factors that may affect ecological interactions within microbial communities, including genomic diversity, habitat specialization, and metabolic versatility. IMPORTANCE Understanding the microbial ecology of the mouth is essential for comprehending human physiology. This study employs metapangenomics to reveal that various Haemophilus and Aggregatibacter species exhibit distinct ecological preferences within the oral cavity of healthy individuals, thereby supporting the site-specialist hypothesis. Additionally, it was observed that the gene pool of different Haemophilus species correlates with their ecological niches. These findings shed light on the significance of key metabolic functions in shaping microbial distribution patterns and interspecies interactions in the oral ecosystem.
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Affiliation(s)
| | | | - Jonathan Tang
- The Forsyth Institute, Cambridge, Massachusetts, USA
| | - Floyd E. Dewhirst
- The Forsyth Institute, Cambridge, Massachusetts, USA
- Harvard School of Dental Medicine, Boston, Massachusetts, USA
| | | | - Jessica L. Mark Welch
- The Forsyth Institute, Cambridge, Massachusetts, USA
- Marine Biological Laboratory, Woods Hole, Massachusetts, USA
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Strange JP, Tripodi AD, Huntzinger C, Knoblett J, Klinger E, Herndon JD, Vuong HQ, McFrederick QS, Irwin RE, Evans JD, Giacomini JJ, Ward R, Adler LS. Comparative analysis of 3 pollen sterilization methods for feeding bumble bees. J Econ Entomol 2023; 116:662-673. [PMID: 36930576 DOI: 10.1093/jee/toad036] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2022] [Revised: 01/24/2023] [Accepted: 02/07/2023] [Indexed: 06/14/2023]
Abstract
Pollen is an essential component of bee diets, and rearing bumble bees (Bombus spp.) for commercial use necessitates feeding pollen in mass quantities. This pollen is collected from honey bee (Apis mellifera L.) colonies because neither an artificial diet nor an economical, large-scale pollen collection process from flowers is available. The provenance of honey bee-collected pollen is often unknown, and in some cases has crossed international borders. Both deformed wing virus (DWV) and the fungal pathogen Ascosphaera apis (Claussen) Olive & Spiltoir (cause of chalkbrood disease); occur in honey bee-collected pollen, and infections have been observed in bumble bees. We used these pathogens as general surrogates for viruses and spore-forming fungal diseases to test the efficacy of 3 sterilization methods, and assessed whether treatment altered pollen quality for the bumble bee. Using honey bee-collected pollen spiked with known doses of DWV and A. apis, we compared gamma irradiation (GI), ozone fumigation (OZ), and ethylene oxide fumigation (EO) against an untreated positive control and a negative control. Following sterilization treatments, we tested A. apis spore viability, detected viral presence with PCR, and tested palatability to the bumble bee Bombus impatiens Cresson. We also measured bacterial growth from pollens treated with EO and GI. GI and EO outperformed OZ treatment in pathogen suppression. EO had the highest sterilizing properties under commercial conditions and retained palatability and supported bee development better than other treatments. These results suggest that EO sterilization reduces pathogen risks while retaining pollen quality as a food source for rearing bumble bees.
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Affiliation(s)
- James P Strange
- USDA-ARS-Pollinating Insect Biology Management and Systematics Research Unit, Logan, UT 84341, United States
- Department of Entomology, The Ohio State University, Columbus, OH 43210, United States
| | | | - Craig Huntzinger
- USDA-ARS-Pollinating Insect Biology Management and Systematics Research Unit, Logan, UT 84341, United States
| | - Joyce Knoblett
- USDA-ARS-Pollinating Insect Biology Management and Systematics Research Unit, Logan, UT 84341, United States
| | - Ellen Klinger
- USDA-ARS-Pollinating Insect Biology Management and Systematics Research Unit, Logan, UT 84341, United States
- Department of Entomology, The Ohio State University, Columbus, OH 43210, United States
| | - James D Herndon
- USDA-ARS-Pollinating Insect Biology Management and Systematics Research Unit, Logan, UT 84341, United States
- Department of Biology, Utah State University, Logan, UT 84321, United States
| | - Hoang Q Vuong
- Department of Entomology, University of California, Riverside, Riverside, CA 92521, United States
| | - Quinn S McFrederick
- Department of Entomology, University of California, Riverside, Riverside, CA 92521, United States
| | - Rebecca E Irwin
- Department of Applied Ecology, NC State University, Raleigh, NC 27695United States
| | - Jay D Evans
- Bee Research Laboratory, Beltsville Agricultural Research Center, US Department of Agriculture, Beltsville, MD 20705, United States
| | - Jonathan J Giacomini
- Department of Applied Ecology, NC State University, Raleigh, NC 27695United States
| | - Robert Ward
- Department of Nutrition, Dietetics and Food Sciences, Utah State University, Logan, UT 84322United States
| | - Lynn S Adler
- Department of Biology, University of Massachusetts, Amherst, MA 01003United States
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Giacomini JJ, Adler LS, Reading BJ, Irwin RE. Differential bumble bee gene expression associated with pathogen infection and pollen diet. BMC Genomics 2023; 24:157. [PMID: 36991318 DOI: 10.1186/s12864-023-09143-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Accepted: 01/18/2023] [Indexed: 03/31/2023] Open
Abstract
BACKGROUND Diet and parasitism can have powerful effects on host gene expression. However, how specific dietary components affect host gene expression that could feed back to affect parasitism is relatively unexplored in many wild species. Recently, it was discovered that consumption of sunflower (Helianthus annuus) pollen reduced severity of gut protozoan pathogen Crithidia bombi infection in Bombus impatiens bumble bees. Despite the dramatic and consistent medicinal effect of sunflower pollen, very little is known about the mechanism(s) underlying this effect. However, sunflower pollen extract increases rather than suppresses C. bombi growth in vitro, suggesting that sunflower pollen reduces C. bombi infection indirectly via changes in the host. Here, we analyzed whole transcriptomes of B. impatiens workers to characterize the physiological response to sunflower pollen consumption and C. bombi infection to isolate the mechanisms underlying the medicinal effect. B. impatiens workers were inoculated with either C. bombi cells (infected) or a sham control (un-infected) and fed either sunflower or wildflower pollen ad libitum. Whole abdominal gene expression profiles were then sequenced with Illumina NextSeq 500 technology. RESULTS Among infected bees, sunflower pollen upregulated immune transcripts, including the anti-microbial peptide hymenoptaecin, Toll receptors and serine proteases. In both infected and un-infected bees, sunflower pollen upregulated putative detoxification transcripts and transcripts associated with the repair and maintenance of gut epithelial cells. Among wildflower-fed bees, infected bees downregulated immune transcripts associated with phagocytosis and the phenoloxidase cascade. CONCLUSIONS Taken together, these results indicate dissimilar immune responses between sunflower- and wildflower-fed bumble bees infected with C. bombi, a response to physical damage to gut epithelial cells caused by sunflower pollen, and a strong detoxification response to sunflower pollen consumption. Identifying host responses that drive the medicinal effect of sunflower pollen in infected bumble bees may broaden our understanding of plant-pollinator interactions and provide opportunities for effective management of bee pathogens.
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Affiliation(s)
- Jonathan J Giacomini
- Department of Applied Ecology, North Carolina State University, Raleigh, NC, 27695, USA.
| | - Lynn S Adler
- Department of Biology, University of Massachusetts Amherst, Amherst, MA, 01003, USA
| | - Benjamin J Reading
- Department of Applied Ecology, North Carolina State University, Raleigh, NC, 27695, USA
| | - Rebecca E Irwin
- Department of Applied Ecology, North Carolina State University, Raleigh, NC, 27695, USA
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Fowler AE, Giacomini JJ, Connon SJ, Irwin RE, Adler LS. Sunflower pollen reduces a gut pathogen in the model bee species, Bombus impatiens, but has weaker effects in three wild congeners. Proc Biol Sci 2022; 289:20211909. [PMID: 35105241 PMCID: PMC8809364 DOI: 10.1098/rspb.2021.1909] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Accepted: 01/04/2022] [Indexed: 12/17/2022] Open
Abstract
Commercial bumblebees have become popular models to understand stressors and solutions for pollinator health, but few studies test whether results translate to other pollinators. Consuming sunflower pollen dramatically reduces infection by the gut parasite Crithidia bombi in commercially reared Bombus impatiens. We assessed the effect of sunflower pollen on infection in wild B. impatiens, Bombus griseocollis, Bombus bimaculatus and Bombus vagans. We also asked how pollen diet (50% sunflower pollen versus wildflower pollen) and infection (yes/no) affected performance in wild B. impatiens microcolonies. Compared to controls, sunflower pollen dramatically reduced Crithidia infection in commercial and wild B. impatiens, had similar but less dramatic effects in B. bimaculatus and B. vagans, and no effect in B. griseocollis. Bombus impatiens, B. bimaculatus and B. vagans are in the same subgenus, suggesting that responses to sunflower pollen may be phylogenetically conserved. In microcolonies, 50% sunflower pollen reduced infection compared to wildflower pollen, but also reduced reproduction. Sunflower pollen could control Crithidia infections in B. impatiens and potentially close relatives, but may hinder reproduction if other resources are scarce. We caution that research using managed bee species, such as B. impatiens, be interpreted carefully as findings may not relate to all bee species.
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Affiliation(s)
- Alison E. Fowler
- Department of Biology, University of Massachusetts Amherst, 221 Morrill Science Center South, 611 North Pleasant Street, Amherst, MA 01003, USA
| | - Jonathan J. Giacomini
- Department of Applied Ecology, North Carolina State University, Raleigh, NC 27695, USA
| | - Sara June Connon
- Department of Applied Ecology, North Carolina State University, Raleigh, NC 27695, USA
| | - Rebecca E. Irwin
- Department of Applied Ecology, North Carolina State University, Raleigh, NC 27695, USA
| | - Lynn S. Adler
- Department of Biology, University of Massachusetts Amherst, 221 Morrill Science Center South, 611 North Pleasant Street, Amherst, MA 01003, USA
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Giacomini JJ, Moore N, Adler LS, Irwin RE. Sunflower pollen induces rapid excretion in bumble bees: Implications for host-pathogen interactions. J Insect Physiol 2022; 137:104356. [PMID: 35016876 DOI: 10.1016/j.jinsphys.2022.104356] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Revised: 12/08/2021] [Accepted: 01/05/2022] [Indexed: 06/14/2023]
Abstract
Host diet can have a profound effect on host-pathogen interactions, including indirect effects on pathogens mediated through host physiology. In bumble bees (Bombus impatiens), the consumption of sunflower (Helianthus annuus) pollen dramatically reduces infection by the gut protozoan pathogen Crithidia bombi. One hypothesis for the medicinal effect of sunflower pollen is that consumption changes host gut physiological function, causing rapid excretion that flushes C. bombi from the system. We tested the effect of pollen diet and C. bombi infection on gut transit properties using a 2x2 factorial experiment in which bees were infected with C. bombi or not and fed sunflower or wildflower pollen diet. We measured several non-mutually exclusive physiological processes that underlie the insect excretory system, including gut transit time, bi-hourly excretion rate, the total number of excretion events and the total volume of excrement. Sunflower pollen significantly reduced gut transit time in uninfected bees, and increased the total number of excretion events and volume of excrement by 66 % and 68 %, respectively, in both infected and uninfected bees. Here we show that a sunflower pollen diet can affect host physiology gut function, causing more rapid and greater excretion. These results provide important insight into a mechanism that could underlie the medicinal effect of sunflower pollen for bumble bees.
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Affiliation(s)
- Jonathan J Giacomini
- Department of Applied Ecology, North Carolina State University, Raleigh, NC 27695 USA.
| | - Nicholas Moore
- Department of Applied Ecology, North Carolina State University, Raleigh, NC 27695 USA
| | - Lynn S Adler
- Department of Biology, University of Massachusetts Amherst, Amherst, MA 01003 USA
| | - Rebecca E Irwin
- Department of Applied Ecology, North Carolina State University, Raleigh, NC 27695 USA
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Giacomini JJ, Connon SJ, Marulanda D, Adler LS, Irwin RE. The costs and benefits of sunflower pollen diet on bumble bee colony disease and health. Ecosphere 2021. [DOI: 10.1002/ecs2.3663] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Affiliation(s)
- Jonathan J. Giacomini
- Department of Applied Ecology North Carolina State University Raleigh North Carolina 27695 USA
| | - Sara J. Connon
- Department of Applied Ecology North Carolina State University Raleigh North Carolina 27695 USA
| | - Daniel Marulanda
- Department of Applied Ecology North Carolina State University Raleigh North Carolina 27695 USA
| | - Lynn S. Adler
- Department of Biology University of Massachusetts Amherst Amherst Massachusetts 01003 USA
| | - Rebecca E. Irwin
- Department of Applied Ecology North Carolina State University Raleigh North Carolina 27695 USA
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Giacomini JJ, Leslie J, Tarpy DR, Palmer-Young EC, Irwin RE, Adler LS. Medicinal value of sunflower pollen against bee pathogens. Sci Rep 2018; 8:14394. [PMID: 30258066 PMCID: PMC6158195 DOI: 10.1038/s41598-018-32681-y] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2018] [Accepted: 09/07/2018] [Indexed: 02/07/2023] Open
Abstract
Global declines in pollinators, including bees, can have major consequences for ecosystem services. Bees are dominant pollinators, making it imperative to mitigate declines. Pathogens are strongly implicated in the decline of native and honey bees. Diet affects bee immune responses, suggesting the potential for floral resources to provide natural resistance to pathogens. We discovered that sunflower (Helianthus annuus) pollen dramatically and consistently reduced a protozoan pathogen (Crithidia bombi) infection in bumble bees (Bombus impatiens) and also reduced a microsporidian pathogen (Nosema ceranae) of the European honey bee (Apis mellifera), indicating the potential for broad anti-parasitic effects. In a field survey, bumble bees from farms with more sunflower area had lower Crithidia infection rates. Given consistent effects of sunflower in reducing pathogens, planting sunflower in agroecosystems and native habitat may provide a simple solution to reduce disease and improve the health of economically and ecologically important pollinators.
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Affiliation(s)
- Jonathan J Giacomini
- North Carolina State University, Department of Applied Ecology, 100 Eugene Brooks Avenue, Raleigh, NC, 27695, USA.
| | - Jessica Leslie
- University of Massachusetts Amherst, Department of Biology, 611 North Pleasant Street, Amherst, MA, 01003, USA
| | - David R Tarpy
- North Carolina State University, Department of Entomology & Plant Pathology, Campus Box 7613, Raleigh, NC 27695, USA
| | - Evan C Palmer-Young
- University of Massachusetts Amherst, Department of Biology, 611 North Pleasant Street, Amherst, MA, 01003, USA
| | - Rebecca E Irwin
- North Carolina State University, Department of Applied Ecology, 100 Eugene Brooks Avenue, Raleigh, NC, 27695, USA
| | - Lynn S Adler
- University of Massachusetts Amherst, Department of Biology, 611 North Pleasant Street, Amherst, MA, 01003, USA
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