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Title: Host selection and stochastic effects influence bacterial community assembly on the microalgal phycosphere

Abstract

Microalgae have major functions in global biogeochemical cycles and are promising sources of renewable energy, yet the relationships between algal hosts and their associated microbiomes remain relatively underexplored. Understanding community organization of microalgal microbiomes, such as how algal species identity influences bacterial community structure, will aid in efforts to engineer more efficient phototrophic ecosystems. Here, we examined the community assembly of phycosphere-associated (attached) and free-living bacterial taxa associated with two marine microalgae: the diatom Phaeodactylum tricornutum and eustigmatophyte Microchloropsis salina. Samples were collected from outdoor mesocosms, raceway ponds, and laboratory enrichments, and bacterial taxa identified by 16S rRNA gene sequences. In outdoor mesocosms, we found distinct bacterial taxa associated with each algal species, including the Cytophagaceae and Rhodobacteraceae families with P. tricornutum, and Rhodobacteraceae, Hyphomonadaceae, and Saprospiraceae with M. salina. Additionally, there were host-specific differences in the bacterial genera associated with the phycosphere, including Novosphingobium and Rhodopirellula with P. tricornutum, and Methylophaga and Dyadobacter with M. salina. Bacterial communities from outdoor monoalgal P. tricornutum and polyalgal P. tricornutum/M. salina samples were used as inocula for laboratory enrichments with axenic P. tricornutum. Here, similar bacterial communities emerged, suggesting that the algal host exerts substantial influence over bacterial community assembly. Further enrichmentsmore » for phycosphere-association revealed differing outcomes of community assembly processes contingent on the initial community composition. Phycosphere-associated communities from monoalgal P. tricornutum mesocosms were highly similar to one another, suggesting deterministic processes, whereas cultures from mixed M. salina/P. tricornutum raceways followed two apparent paths differentiated by the stochastic loss of specific community members and convergence towards or further deviation from the monoalgal samples. These results demonstrate that algal-associated bacterial communities are controlled by algal host, culture conditions, and the initial inoculum composition of the algal microbiome, and this knowledge can inform the engineering of more productive algal systems.« less

Authors:
ORCiD logo [1];  [1];  [1];  [1];  [1];  [2]; ORCiD logo [3];  [4];  [1]
  1. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  2. Texas A & M Univ., College Station, TX (United States); Georgia Southern Univ., Statesboro, GA (United States)
  3. Texas A & M Univ., College Station, TX (United States)
  4. Sandia National Lab. (SNL-CA), Livermore, CA (United States)
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
OSTI Identifier:
1547537
Alternate Identifier(s):
OSTI ID: 1548383
Report Number(s):
LLNL-JRNL-732570
Journal ID: ISSN 2211-9264; 884045
Grant/Contract Number:  
AC52-07NA27344; SCW1039
Resource Type:
Published Article
Journal Name:
Algal Research
Additional Journal Information:
Journal Volume: 40; Journal Issue: C; Journal ID: ISSN 2211-9264
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; 59 BASIC BIOLOGICAL SCIENCES

Citation Formats

Kimbrel, Jeffrey A., Samo, Ty J., Ward, Christopher, Nilson, Daniel, Thelen, Michael P., Siccardi, Anthony, Zimba, Paul, Lane, Todd W., and Mayali, Xavier. Host selection and stochastic effects influence bacterial community assembly on the microalgal phycosphere. United States: N. p., 2019. Web. doi:10.1016/j.algal.2019.101489.
Kimbrel, Jeffrey A., Samo, Ty J., Ward, Christopher, Nilson, Daniel, Thelen, Michael P., Siccardi, Anthony, Zimba, Paul, Lane, Todd W., & Mayali, Xavier. Host selection and stochastic effects influence bacterial community assembly on the microalgal phycosphere. United States. doi:10.1016/j.algal.2019.101489.
Kimbrel, Jeffrey A., Samo, Ty J., Ward, Christopher, Nilson, Daniel, Thelen, Michael P., Siccardi, Anthony, Zimba, Paul, Lane, Todd W., and Mayali, Xavier. Fri . "Host selection and stochastic effects influence bacterial community assembly on the microalgal phycosphere". United States. doi:10.1016/j.algal.2019.101489.
@article{osti_1547537,
title = {Host selection and stochastic effects influence bacterial community assembly on the microalgal phycosphere},
author = {Kimbrel, Jeffrey A. and Samo, Ty J. and Ward, Christopher and Nilson, Daniel and Thelen, Michael P. and Siccardi, Anthony and Zimba, Paul and Lane, Todd W. and Mayali, Xavier},
abstractNote = {Microalgae have major functions in global biogeochemical cycles and are promising sources of renewable energy, yet the relationships between algal hosts and their associated microbiomes remain relatively underexplored. Understanding community organization of microalgal microbiomes, such as how algal species identity influences bacterial community structure, will aid in efforts to engineer more efficient phototrophic ecosystems. Here, we examined the community assembly of phycosphere-associated (attached) and free-living bacterial taxa associated with two marine microalgae: the diatom Phaeodactylum tricornutum and eustigmatophyte Microchloropsis salina. Samples were collected from outdoor mesocosms, raceway ponds, and laboratory enrichments, and bacterial taxa identified by 16S rRNA gene sequences. In outdoor mesocosms, we found distinct bacterial taxa associated with each algal species, including the Cytophagaceae and Rhodobacteraceae families with P. tricornutum, and Rhodobacteraceae, Hyphomonadaceae, and Saprospiraceae with M. salina. Additionally, there were host-specific differences in the bacterial genera associated with the phycosphere, including Novosphingobium and Rhodopirellula with P. tricornutum, and Methylophaga and Dyadobacter with M. salina. Bacterial communities from outdoor monoalgal P. tricornutum and polyalgal P. tricornutum/M. salina samples were used as inocula for laboratory enrichments with axenic P. tricornutum. Here, similar bacterial communities emerged, suggesting that the algal host exerts substantial influence over bacterial community assembly. Further enrichments for phycosphere-association revealed differing outcomes of community assembly processes contingent on the initial community composition. Phycosphere-associated communities from monoalgal P. tricornutum mesocosms were highly similar to one another, suggesting deterministic processes, whereas cultures from mixed M. salina/P. tricornutum raceways followed two apparent paths differentiated by the stochastic loss of specific community members and convergence towards or further deviation from the monoalgal samples. These results demonstrate that algal-associated bacterial communities are controlled by algal host, culture conditions, and the initial inoculum composition of the algal microbiome, and this knowledge can inform the engineering of more productive algal systems.},
doi = {10.1016/j.algal.2019.101489},
journal = {Algal Research},
number = C,
volume = 40,
place = {United States},
year = {2019},
month = {4}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record
DOI: 10.1016/j.algal.2019.101489

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