Corresponding author: Claudia Piccini (
Academic editor: Chloe Robinson
The authors declare no conflicts of interest
The close association between bacteria and
The synthesis of the external polysaccharide-rich (EPS) matrix that surrounds the cyanobacterial cells is thought to be a physiological response to fluctuations in environmental conditions, allowing bacteria to maintain their fitness and also the associated microbiota (
In some toxic bacteria, such as
Although it is proposed that the success of this species in tolerating, colonising and adapting to different environmental conditions (temperature, light and nutrients) is due to a strategy combining phenotypic plasticity (
This is the first description of the heterotrophic bacterial community associated with
We analysed the microbiome of two strains of
Static cultures of both strains were grown in a nitrogen-free BG11 medium (
To harvest the cells, samples were filtered on to 2 μm pore size polycarbonate hydrophilic membranes. The DNA extraction was performed as described in
The 16S rRNA gene was amplified (three pooled technical replicates) and sequencing at the Macrogen Sequencing Service (South Korea). Sequencing libraries were prepared according to the Illumina 16S Metagenomic Sequencing Library protocols to amplify the V3-V4. Primer sequences used for the first amplifications were as follows: 341F/805R(V3-V4, 341F: CCTACGGGNGGCWGCAG, 805R: GACTACHVGGGTATCTAATCC) (
Bioinformatic analyses of the microbiome were performed in R (version 4.1.0) using the DADA2 package (
The composition of bacterial microbiomes at different taxonomic levels was analysed with the Phyloseq package (
This study was focused on the microbiome of the bloom-forming cyanobacterium
16S ribosomal ARN gene.
Bacterial domain.
Sequence data from this study have been deposited to NCBI SRA database. Resource identifiers are PRJNA737279 for the taxa obtained from
Download URL:
Resource identifier: PRJNA737279
Data format : FASTQ
Download URL:
Resource identifier: PRJNA737280
Data format : FASTQ
After filtering by quality, denoising, merging and removing the chimeras, a total of 50,753 and 35,908 reads were obtained for the microbiome of LB2897 and MVCC19, respectively. They were clustered into amplicon sequence variants (ASVs) with 100% sequence identity. Taxa richness was 31 and 22 and Shannon Diversity was 2.2 and 2.4 for LB2897 and MVCC19, respectively. Bray–Curtis Distance Index between both microbiomes was 0.26. The most represented phylum was
In both microbiomes, few bacterial genera accounted for more than 50% of the community. In the case of the SxP (
In the NoP (
Taxonomic composition of the microbiome
The data, presented in this work, show that the composition of the bacterial community inhabiting the EPS of two strains of
In the SxP ecotype, a genus affiliated to
Other abundant bacterial groups associated to the SxP strain have been found in environments contaminated with polycyclic aromatic hydrocarbons (
Hence, the microbiome community, inhabiting the phycosphere of
Moreover, some of the taxa, accounting for the higher bacterial richness observed in the NoP microbiome, showed relative abundances ranging from 0.1 to 12.4% and were affiliated to
We found that the dominant bacterial genus in SxP and NoP microbiomes is involved in nitrogen metabolism. Interestingly, while the
The cultures of both strains were performed without added nitrogen, which implies that nitrogen fixation is the main way of obtaining the needed reduced nitrogen to growth. Further studies involving different nitrogen concentrations in the culture medium should be performed in order to determine if the dominant members of the microbiome are still those related to nitrogen cycling.
Caveats and Limitations
Sequence data from this study will be publicly available at NCBI.
Usage Rights
This work was supported by PEDECIBA and CSIC-Universidad de la República and was carried out in partial fulfilment of the requirements of P.V. for the Doctoral degree from PEDECIBA. P.V. was the recipient of a fellowship from ANII (Agencia Nacional de Investigación e Innovación, Uruguay).
Paula Vico - laboratory work, bioinformatic analysis, writing.
Andrés Iriarte - bioinformatic analysis, supervision, writing, revision.
Sylvia Bonilla - laboratory work (supervision of strains growth), revision.
Claudia Piccini - laboratory work, supervision, writing, revision.
The authors declare no conflicts of interest
Relative abundance of bacterial phyla found in
Abundance of the bacterial genera found in the microbiome of SxP (toxic MVCC19) and NoP (non-toxic LB2897) ecotypes of
Morphology, toxicity and biogeographic characteristics of
|
|
|
|
Lago Javiera |
Lemon Lakeb |
|
Eutrophic artificial lake/recreationa | Artificial lake/recreationb |
|
Subtropicala | Temperedb |
|
0.235a | 6677b |
|
10a | 6.1b |
|
0.48 ± 0.02 (6) /0.55 ± 0.02 (6)c | 0.154 ± 27.54 (18)/0.156 ± 33.1(18)b |
|
8.4 ± 0.08 (53)a | 8.08 ± 1.01 (21)b |
|
11/25.8a | -5.0/30.0b |
|
0.083 ± 0.008 (54)a | 0.077 ± 0.03 (30)b |
|
||
|
Straight and separate | Straight and slightly curved, bonded |
|
130.3 ± 55 (50) | 162 ± 84 (50) |
|
2.57 ± 0.4 (50) | 2.09 ± 0.26 (50) |
|
8.3 ± 0.4 (30) | 8.5 ± 0.6 (30) |
|
590.2 (50) | 556.11 (50) |
|
Terminal | Terminal |
|
Yesd,e | Nod,e |
|
Nod | Nod |
|
South American cladee | Ancestral to South American clade and related to Northern Africa strains e |
GenBank retrieved sequences having more than 97% identity with the ASVs obtained in this study.
|
|
|
|
|
LB2897 | MVCC19 | |||
|
|
13.79 | Uncultured bacterium partial 16S rRNA gene (99%) |
Wastewater treatment system |
|
20.54 | 5.80 | Uncultured |
Sewage sludge of the completely autotrophic nitrogen removal over nitrite process with a submerged aerated biological filter and the effect of inorganic carbon on nitrogen removal and microbial activity. |
|
13.35 | 0.00 | Uncultured alpha proteobacterium clone cafs1349 (100%) |
Floodplain lake water |
|
12.36 | 0 | More than 100 sequences having 100% identity, including |
Oral microbiome. Isolation and Characterization of Predominant Microorganisms during decomposition of Waste Materials in a Field-Scale Composter |
|
10.74 | 0 | Freshwater sediment | |
|
0.23 |
|
Cyanobacterial aggregates | |
|
0 | 12.30 | Water. Constructed wetlands. Ice | |
|
0.24 | 9.64 | Daphnia is a reservoir for mercury-tolerant |
|
|
2.03 | 2.86 | Uncultured bacterium clone SIP21-RS-6 (99%) |
Rice rhizospheric soil |
|
0.80 | 6.47 | Groundwater | |
|
2.36 | 0 | Uncultured bacterium clone Wat111 (100%) |
Bacterial Community Structure on |
|
0.91 | 4.23 |
|
Eutrophic lake. associated with cyano-bloom |
|
0 | 5.68 | Uncultured bacterium clone SPN0-300day-93 (99%) |
PAHs contaminated soil |
|
1.81 | 0 | Uncultured bacterium clone (100%) |
Down-flow Hanging Sponge (DHS) reactor treating toluene gas as carbon source |
|
1.94 | 0 | Uncultured bacterium clone (100%) |
Wastewater treatment system |
|
0.00 | 9.76 | Uncultured bacterium clone PlExp_89 (97%) |
Impact of manufactured TiO nanoparticles on planktonic and sessile bacterial communities (Moselle river) |
|
1.60 | 0.25 | Uncultured |
Hot water biofilm after heat shock |
|
1.23 | 1.14 | Groundwater | |
|
1.12 | 0 | Uncultured |
Sewage sludge of the completely autotrophic nitrogen removal over nitrite process with a submerged aerated biological filter and the effect of inorganic carbon on nitrogen removal and microbial activity. |
|
0.75 | 0 | Uncultured bacterium clone F5K2Q4C04I6QGN (99%) |
Activated sludge |
|
0 | 1.88 | Groundwater | |
|
0 | 1.82 | Uncultured bacterium clone HK31-1-39-10 (100%) |
Basaltic subsurface ecosystems |
|
0.55 | 0.25 | Uncultured bacterium clone N3 (100%) |
Biologically activated carbon for drinking water treatment |
|
0.36 | 0.10 | Uncultured bacterium clone SZB6 (100%) |
Mangrove sediment |
|
0 | 0.80 | Chimney Hills Pond, Tulsa | |
|
0.18 | 0.00 | Uncultured bacterium (100%) |
Wastewater treatment system |
|
0.15 | 0.29 | Root of aquatic plant | |
|
0.11 | 0 | Uncultured bacterium clone MPB2-18 (99%) |
Microflorae of aquatic moss pillars in a freshwater lake, East Antarctica |
|
0.09 | 0 | Exopolysaccharide-producing |
|
|
0.07 | 0 | ||
|
0.07 | 0 | Spacecraft associated microbial organisms from the Mars odyssey and Pathfinder missions | |
|
0.04 | 0.08 | ||
|
0.06 | 0 | Uncultured prokaryote clone OTU029 (99%) |
Drinking water biofilm |
|
0.05 | 0 | Uncultured |
Water from long-term experimental oligotrophic mesocosms in Cuatro Cienegas" |
|
0.05 | 0 | Uncultured bacterium clone Espejo_1_17_12_Water.240996 (98%) |
Water from Espejo lake, Argentina |
|
0.03 | 0.06 | Uncultured bacterium clone FL_03_167 (100%) |
Bacterial communities associated to |
|
0 | 0.14 | Uncultured bacterium clone LNH_9_9_11_Pumice.207741 (99%) |
Water from Nahuel Huapi lake, Argentina |
|
0 | 0.14 | No match | - |
|
0.04 | 0 | Uncultured bacterium clone EF_bacC09 |
Sediment from slow sand filtration columns (wastewater) |
Sequence ASV table
Phylogenetic
The representative sequence of each identified ASV and their taxonomic identity according to SILVA database are shown.
File: oo_572950.xls
Rarefaction curves
image
Rarefaction curves obtained from the 16S rRNA gene sequencing for each
File: oo_598214.tiff