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Abstract Detail



Comparative Genomics/Transcriptomics

Parks, Matthew [1], Wickett, Norman [2], Alverson, Andrew [3].

Characterizing persistent bacterial co-habitants and their genetic contribution to an araphid pennate diatom.

Diatoms (Bacillariophyta) are photosynthetic microbial eukaryotes with critical global roles in carbon and nutrient cycling. Diatoms also interact with bacterial taxa inhabiting the diatom phycosphere, including for iron and nitrogen uptake, cell division, and biofilm formation, and a significant portion of diatom genes originate from bacterial-to-diatom horizontal gene transfer events. We assembled the first genome of an araphid pennate diatom, Psammoneis japonica Shin.Sato, Kooistra & Medlin, from a combination of Illumina and Pacific BioSciences sequencing data to an estimated genome size of 91.4Mbp (N50=380Kbp). Assembly of four distinct and complete bacterial genomes from putatively axenic Psammoneis culture supports a requisite relationship between this species and bacterial phycosphere residents. We did not detect unique primary or secondary metabolic pathways in these bacteria compared to closely related taxa. However, at least one Psammoneis gene with strong parametric-based support for horizontal gene transfer, and at least seven orthologous genes in the Psammoneis genome, were supported as originating in one of the co-habiting bacterial lineages. This suggests specific diatom-bacterial relationships are stable over potentially millions of years. Structural modeling of these proteins and related proteins in the putative HGT donor bacterial genome supports extracellular and membrane-surface localization. This suggests possible roles in bacterial adhesion or bacterial-diatom signaling, although we were unable to explicitly identify ‘partner’ proteins in any of our assembled bacterial genomes.


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1 - Chicago Botanic Garden, 1000 Lake Cook Road, Glencoe, IL, 60022, United States
2 - Chicago Botanic Garden, 1000 Lake Cook Rd., Glencoe, IL, 60022, United States
3 - University of Arkansas, Department of Biological Sciences, 1 University of Arkansas, SCEN 601, Fayetteville, AR, 72701, USA

Keywords:
Diatoms
phycosphere
bacteria
horizontal gene transfer.

Presentation Type: Oral Paper
Session: 25, Comparative Genomics and Transcriptomics II
Location: 102/Mayo Civic Center
Date: Tuesday, July 24th, 2018
Time: 5:15 PM
Number: 25017
Abstract ID:884
Candidate for Awards:Margaret Menzel Award


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