Limits...
Identification of Associations between Bacterioplankton and Photosynthetic Picoeukaryotes in Coastal Waters.

Farnelid HM, Turk-Kubo KA, Zehr JP - Front Microbiol (2016)

Bottom Line: Photosynthetic picoeukaryotes are significant contributors to marine primary productivity.The results show that diverse bacterial phylotypes are found in association with photosynthetic picoeukaryotes.Taxonomic identification of these associations is a prerequisite for further characterizing and to elucidate their metabolic pathways and ecological functions.

View Article: PubMed Central - PubMed

Affiliation: Ocean Sciences Department, University of California at Santa CruzSanta Cruz, CA, USA; Centre for Ecology and Evolution in Microbial Model Systems, Linnaeus UniversityKalmar, Sweden.

ABSTRACT
Photosynthetic picoeukaryotes are significant contributors to marine primary productivity. Associations between marine bacterioplankton and picoeukaryotes frequently occur and can have large biogeochemical impacts. We used flow cytometry to sort cells from seawater to identify non-eukaryotic phylotypes that are associated with photosynthetic picoeukaryotes. Samples were collected at the Santa Cruz wharf on Monterey Bay, CA, USA during summer and fall, 2014. The phylogeny of associated microbes was assessed through 16S rRNA gene amplicon clone and Illumina MiSeq libraries. The most frequently detected bacterioplankton phyla within the photosynthetic picoeukaryote sorts were Proteobacteria (Alphaproteobacteria and Gammaproteobacteria) and Bacteroidetes. Intriguingly, the presence of free-living bacterial genera in the photosynthetic picoeukaryote sorts could suggest that some of the photosynthetic picoeukaryotes were mixotrophs. However, the occurrence of bacterial sequences, which were not prevalent in the corresponding bulk seawater samples, indicates that there was also a selection for specific OTUs in association with photosynthetic picoeukaryotes suggesting specific functional associations. The results show that diverse bacterial phylotypes are found in association with photosynthetic picoeukaryotes. Taxonomic identification of these associations is a prerequisite for further characterizing and to elucidate their metabolic pathways and ecological functions.

No MeSH data available.


Neighbor-joining phylogenetic tree of 97% similarity clustered non-Eukaryota sequences in 16S rRNA gene clone libraries from photosynthetic picoeukaryote cell sorts (P1, 1,000 cells) and their closest relatives. GenBank accession numbers are written in square brackets for the closest relatives and in bold for the representative clones. Colored circles indicate the number of sequences in each cluster and the corresponding date for each clone. Bootstrap values >50% (1,000 replicates) are indicated next to the node.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4834442&req=5

Figure 2: Neighbor-joining phylogenetic tree of 97% similarity clustered non-Eukaryota sequences in 16S rRNA gene clone libraries from photosynthetic picoeukaryote cell sorts (P1, 1,000 cells) and their closest relatives. GenBank accession numbers are written in square brackets for the closest relatives and in bold for the representative clones. Colored circles indicate the number of sequences in each cluster and the corresponding date for each clone. Bootstrap values >50% (1,000 replicates) are indicated next to the node.

Mentions: The most frequently detected phylum among the non-Eukaryota sequences was Proteobacteria including Alphaproteobacteria and Gammaproteobacteria (Figure 2). Several clusters were detected on multiple sampling dates (Figure 2). In the summer samples, sequences within the Roseobacter clade were found. Members of the Roseobacter clade are one of the most abundant groups of pelagic bacterioplankton and have a central role in organic sulfur cycling (González et al., 1999). Within this clade, a cluster of sequences (KT906717; Figure 2) were 99% identical to a symbiont of the brittle star Ophiopholis aculeata (accession number U63548) and a Single Amplified Genome (SAG) from the Gulf of Maine (SAG ID MS024-1C; Stepanauskas and Sieracki, 2007). In the October 8 sample, an alphaproteobacterial cluster (KT906762; Figure 2) was 99% identical to a sequence from a photosynthetic picoeukaryote population sort from Station ALOHA in the Pacific Ocean (accession number EU187888; Zehr et al., 2008). The largest gammaproteobacterial cluster (KT906757; Figure 2) contained sequences from five sampling days and was related to SAR86, an abundant uncultivated marine bacterial clade that is metabolically streamlined (Dupont et al., 2012). In summary, the clone library results showed that sequences from associated bacterioplankton could be amplified from the sorted photosynthetic picoeukaryote populations.


Identification of Associations between Bacterioplankton and Photosynthetic Picoeukaryotes in Coastal Waters.

Farnelid HM, Turk-Kubo KA, Zehr JP - Front Microbiol (2016)

Neighbor-joining phylogenetic tree of 97% similarity clustered non-Eukaryota sequences in 16S rRNA gene clone libraries from photosynthetic picoeukaryote cell sorts (P1, 1,000 cells) and their closest relatives. GenBank accession numbers are written in square brackets for the closest relatives and in bold for the representative clones. Colored circles indicate the number of sequences in each cluster and the corresponding date for each clone. Bootstrap values >50% (1,000 replicates) are indicated next to the node.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4834442&req=5

Figure 2: Neighbor-joining phylogenetic tree of 97% similarity clustered non-Eukaryota sequences in 16S rRNA gene clone libraries from photosynthetic picoeukaryote cell sorts (P1, 1,000 cells) and their closest relatives. GenBank accession numbers are written in square brackets for the closest relatives and in bold for the representative clones. Colored circles indicate the number of sequences in each cluster and the corresponding date for each clone. Bootstrap values >50% (1,000 replicates) are indicated next to the node.
Mentions: The most frequently detected phylum among the non-Eukaryota sequences was Proteobacteria including Alphaproteobacteria and Gammaproteobacteria (Figure 2). Several clusters were detected on multiple sampling dates (Figure 2). In the summer samples, sequences within the Roseobacter clade were found. Members of the Roseobacter clade are one of the most abundant groups of pelagic bacterioplankton and have a central role in organic sulfur cycling (González et al., 1999). Within this clade, a cluster of sequences (KT906717; Figure 2) were 99% identical to a symbiont of the brittle star Ophiopholis aculeata (accession number U63548) and a Single Amplified Genome (SAG) from the Gulf of Maine (SAG ID MS024-1C; Stepanauskas and Sieracki, 2007). In the October 8 sample, an alphaproteobacterial cluster (KT906762; Figure 2) was 99% identical to a sequence from a photosynthetic picoeukaryote population sort from Station ALOHA in the Pacific Ocean (accession number EU187888; Zehr et al., 2008). The largest gammaproteobacterial cluster (KT906757; Figure 2) contained sequences from five sampling days and was related to SAR86, an abundant uncultivated marine bacterial clade that is metabolically streamlined (Dupont et al., 2012). In summary, the clone library results showed that sequences from associated bacterioplankton could be amplified from the sorted photosynthetic picoeukaryote populations.

Bottom Line: Photosynthetic picoeukaryotes are significant contributors to marine primary productivity.The results show that diverse bacterial phylotypes are found in association with photosynthetic picoeukaryotes.Taxonomic identification of these associations is a prerequisite for further characterizing and to elucidate their metabolic pathways and ecological functions.

View Article: PubMed Central - PubMed

Affiliation: Ocean Sciences Department, University of California at Santa CruzSanta Cruz, CA, USA; Centre for Ecology and Evolution in Microbial Model Systems, Linnaeus UniversityKalmar, Sweden.

ABSTRACT
Photosynthetic picoeukaryotes are significant contributors to marine primary productivity. Associations between marine bacterioplankton and picoeukaryotes frequently occur and can have large biogeochemical impacts. We used flow cytometry to sort cells from seawater to identify non-eukaryotic phylotypes that are associated with photosynthetic picoeukaryotes. Samples were collected at the Santa Cruz wharf on Monterey Bay, CA, USA during summer and fall, 2014. The phylogeny of associated microbes was assessed through 16S rRNA gene amplicon clone and Illumina MiSeq libraries. The most frequently detected bacterioplankton phyla within the photosynthetic picoeukaryote sorts were Proteobacteria (Alphaproteobacteria and Gammaproteobacteria) and Bacteroidetes. Intriguingly, the presence of free-living bacterial genera in the photosynthetic picoeukaryote sorts could suggest that some of the photosynthetic picoeukaryotes were mixotrophs. However, the occurrence of bacterial sequences, which were not prevalent in the corresponding bulk seawater samples, indicates that there was also a selection for specific OTUs in association with photosynthetic picoeukaryotes suggesting specific functional associations. The results show that diverse bacterial phylotypes are found in association with photosynthetic picoeukaryotes. Taxonomic identification of these associations is a prerequisite for further characterizing and to elucidate their metabolic pathways and ecological functions.

No MeSH data available.