Umeå University's logo

umu.sePublications
Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Bacteria that escape predation: waterborne pathogens and their relatives
Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. CBRN Defence and Security, Swedish Defence Research Agency, Sweden. (UMFpub; EcoChange)
2023 (English)Doctoral thesis, comprehensive summary (Other academic)Alternative title
Bakterier som undkommer predation : vattenlevande patogener och deras släktingar (Swedish)
Abstract [en]

The hidden presence of opportunistic bacterial pathogens in the environment evokes concerns about emerging diseases, especially in the light of climate change. The co-evolution of bacteria and their predators (protozoa) has led to bacterial defence strategies of which some contribute to the ability of bacteria to cause disease. To increase our understanding of the interplay between bacteria, protozoa, land use, and climate scenarios in Nordic brackish and freshwater, four studies were designed. The first study explored the co-occurrence patterns between predation resistant bacteria (PRB) and bacterivorous protozoa in a coastal area in the northern Baltic Sea. The results showed higher PRB diversity in the bays and freshwater inlets, than in the offshore waters. Further, genotype specific interactions between protozoa and bacteria were identified. The second study focused on Legionella species diversity and their association with humic substances and low salinity, potentially facilitated through the promotion of the heterotrophic microbial food web or by iron availability. The third study examined the impact of intensified land use on bacterial taxa abundance and community composition in lake inflows, demonstrating indirect downstream effects on water quality. Factors such as pastures, fields, farms, aluminium, iron, and humic substances were linked to increased Legionella abundance. The fourth study exposed aquatic organisms to climate change scenarios, causing eutrophication or brownification with elevated iron levels. Pseudomonas aeruginosa were found to be especially persistent to iron, likely linked to the same mechanism that enables survival in protozoan cells. This trait was shared with other observed intracellular pathogens and uncultured species, who showed elevated resilience to brownification and ability to survive outside host cells. These findings identified complex relationships, which improve our understanding of the intricate dynamics that shape aquatic ecosystems, and highlight the importance of considering multiple factors in managing water resources and maintaining ecosystem health. Human activities including intensified land use can have far-reaching consequences, jeopardizing the pristine nature of water bodies and escalate the presence of environmental and opportunistic bacterial pathogens.

Place, publisher, year, edition, pages
Umeå: Umeå University, 2023. , p. 62
Keywords [en]
bacterial pathogens, protozoa, predation resistance, aquatic microbiology, climate change, opportunists, humification, iron
National Category
Oceanography, Hydrology and Water Resources
Research subject
environmental science; Microbiology
Identifiers
URN: urn:nbn:se:umu:diva-216610ISBN: 9789180702058 (electronic)ISBN: 9789180702041 (print)OAI: oai:DiVA.org:umu-216610DiVA, id: diva2:1811621
Public defence
2023-12-08, SAM.A.280, Samhällsvetarhuset, Umeå, 09:00 (English)
Opponent
Supervisors
Available from: 2023-11-17 Created: 2023-11-13 Last updated: 2023-12-20Bibliographically approved
List of papers
1. Microbial Interactions - Underexplored Links Between Public Health Relevant Bacteria and Protozoa in Coastal Environments
Open this publication in new window or tab >>Microbial Interactions - Underexplored Links Between Public Health Relevant Bacteria and Protozoa in Coastal Environments
2022 (English)In: Frontiers in Microbiology, E-ISSN 1664-302X, Vol. 13, article id 877483Article in journal (Refereed) Published
Abstract [en]

The co-existence of bacteria and protozoa in aquatic environments has led to the evolution of predation defense mechanisms by the bacteria. Some of the predation-resistant bacteria (PRB) are also pathogenic to humans and other mammals. The links between PRB and protozoa in natural aquatic systems are poorly known, but they are important in predicting outbreaks and determining the long-term consequences of a contamination event. To elucidate co-occurrence patterns between PRB (16S rRNA) and bacterivorous protozoa (18S rRNA), we performed a field study in a coastal area in the northern Baltic Sea. Interactions between bacteria and protozoa were explored by using two complementary statistical tools. We found co-occurrence patterns between specific PRB and protozoa, such as Legionella and Ciliophora, and we also found that the interactions are genotype-specific as, for example, Rickettsia. The PRB sequence diversity was larger in bays and freshwater inlets compared to offshore sites, indicating local adaptions. Considering the PRB diversity in the freshwater in combination with the large spring floods in the area, freshwater influxes should be considered a potential source of PRB in the coastal northern Baltic Sea. These findings are relevant for the knowledge of survival and dispersal of potential pathogens in the environment.

Place, publisher, year, edition, pages
Frontiers Media S.A., 2022
Keywords
aquatic microbiology, bacteria, biotic interactions, co-evolution, direct acyclic graph (DAG), joint species distribution model, predation resistance, protozoa
National Category
Ecology
Identifiers
urn:nbn:se:umu:diva-196973 (URN)10.3389/fmicb.2022.877483 (DOI)000816889300001 ()35770179 (PubMedID)2-s2.0-85133551087 (Scopus ID)
Available from: 2022-06-21 Created: 2022-06-21 Last updated: 2024-01-17Bibliographically approved
2. Association between Legionella species and humic substances during early summer in the northern Baltic Sea
Open this publication in new window or tab >>Association between Legionella species and humic substances during early summer in the northern Baltic Sea
Show others...
2023 (English)In: Frontiers in Marine Science, E-ISSN 2296-7745, Vol. 9, article id 1070341Article in journal (Refereed) Published
Abstract [en]

Climate change is projected to cause alterations in northern coastal systems, including humification and intensified nutrient loads, which can lead to ecosystem imbalances and establishment of new bacterial species. Several potential pathogens, such as different species of Legionella, hide in the environment between infections, some by living inside protozoan host cells. Knowledge about the occurrence of Legionella in natural waters is missing, which disable risk assessments of exposure. We performed a study of the species diversity of Legionella in the northern Baltic Sea (Gulf of Bothnia) during early summer to map their occurrence and to identify possible environmental drivers. We detected Legionella and potential protozoan hosts along gradients of the Gulf of Bothnia. We also for the first time present third generation full-length 16S rRNA amplicon sequencing (Nanopore) to resolve environmental species classification of Legionella, with a method suitable to study all bacteria. Our data show that full length 16S rRNA sequences is sufficient to resolve Legionella while the standard short Illumina sequences did not capture the entire diversity. For accurate species classification of Legionella, harmonization between the Nanopore classification methods is still needed and the bias toward the well-studied Legionella pneumophila need to be resolved. Different Legionella species occurred both in the Bothnian Sea and in the Bothnian Bay and their abundance were linked to humic substances and low salinity. The relative abundance of Legionella was higher in the humic-rich northern waters of the Bothnian Bay. The link between Legionella species and humic substances may be indirect via promotion of the heterotrophic microbial food web, allowing Legionella species and similar bacteria to establish. Humic substances are rich in iron, which has been shown crucial for growth of Legionella species and other pathogens. Considering climate change projections in this regional area, with increased humification and freshwater inflow, this bacterial niche containing potential pathogens might become more widespread in the future Baltic Sea. This study demonstrates the significance of DNA sequencing to monitor public health relevant bacteria like Legionella species in the environment. Including sequencing of bacteria and protozoa in the environmental monitoring programs could be used to identify ecosystem imbalances, which enable appropriate responses to emerging diseases.

Place, publisher, year, edition, pages
Frontiers Media S.A., 2023
Keywords
Legionella, protozoa, predation resistance, aquatic microbiology, climate change, ecology change, marginal seas, humification
National Category
Ecology
Identifiers
urn:nbn:se:umu:diva-203899 (URN)10.3389/fmars.2022.1070341 (DOI)000924634400001 ()2-s2.0-85147432283 (Scopus ID)
Funder
Ecosystem dynamics in the Baltic Sea in a changing climate perspective - ECOCHANGESwedish Research Council FormasSwedish Armed Forces
Available from: 2023-01-23 Created: 2023-01-23 Last updated: 2023-11-13Bibliographically approved
3. Upstream land use with microbial downstream consequences: iron and humic substances link to Legionella spp.
Open this publication in new window or tab >>Upstream land use with microbial downstream consequences: iron and humic substances link to Legionella spp.
Show others...
(English)Manuscript (preprint) (Other academic)
National Category
Oceanography, Hydrology and Water Resources
Identifiers
urn:nbn:se:umu:diva-216607 (URN)
Available from: 2023-11-13 Created: 2023-11-13 Last updated: 2024-04-22
4. Who are the waterborne pathogens of the future?: Opportunistic bacterial persistence to predation, organic matter, and iron
Open this publication in new window or tab >>Who are the waterborne pathogens of the future?: Opportunistic bacterial persistence to predation, organic matter, and iron
Show others...
(English)Manuscript (preprint) (Other academic)
National Category
Oceanography, Hydrology and Water Resources
Identifiers
urn:nbn:se:umu:diva-216609 (URN)
Available from: 2023-11-13 Created: 2023-11-13 Last updated: 2023-11-14

Open Access in DiVA

fulltext(1284 kB)223 downloads
File information
File name FULLTEXT01.pdfFile size 1284 kBChecksum SHA-512
76aebe6ff1b2fc806bf2d2c47905f37023ad0d33d6dbe84ac99b4a4cb3c743df8f1d54d1217fdc7d8624e9022e3a72f3e6872164e2da6de3a48d7c49086d71de
Type fulltextMimetype application/pdf
spikblad(373 kB)35 downloads
File information
File name SPIKBLAD01.pdfFile size 373 kBChecksum SHA-512
cb7bce0f421cacd10e71235490b5951a3277b37f5d60da63bd0d35179fa8a54cdca13560bf063f5bf84abe378483607b2ff805f3bc4473c11982c3a58120ec2f
Type spikbladMimetype application/pdf

Authority records

Eriksson, Karolina I. A.

Search in DiVA

By author/editor
Eriksson, Karolina I. A.
By organisation
Department of Ecology and Environmental Sciences
Oceanography, Hydrology and Water Resources

Search outside of DiVA

GoogleGoogle Scholar
Total: 223 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

isbn
urn-nbn

Altmetric score

isbn
urn-nbn
Total: 827 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf