Poster at Bertinoro (2018)

1. Microbial diversity in deep sediments of Lake Baikal
Who’s in there? – Preliminary results
1 Ecologie Systéma/que Evolu/on, Centre Na/onal de la Recherche Scien/fique (CNRS), Université Paris-Sud,Orsay, France ; 2 Limnological Ins/tute, Siberian Branch of the Russian Academy of Sciences, Irkutsk, Russia
* Corresponding author: guillaume.reboul@u-psud.fr
Reboul G. *,1, Moreira D. 1, Bertolino, P. 1, Galindo L. 1, Annenkova NV. 2, López-García P. *,1
Eukaryotic diversity
Archaeal diversity
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Sediment
samples
Sediment depth (m)
Number of reads after cleaning and merging paired-end reads
16S (290bp amplicons) 18S (527bp amplicons)
BK03S 1,081 269,945 ND
BK05S 1,450 258,956 105,975
BK16S 846 269,623 73,279
BK21S 373 319,902 255,442
BK22S 592 ND 198,890
BK25S 323 137,204 178,187
BK26S 1,412 95,952 57,340
BK30S 1,381 138,735 351,975
DPANN
TACK
Euryarchaeota
Pairwise Bray-Curtis dissimilarity matrix based on archaeal OTU frequencies
BK03S BK05S BK16S BK21S BK25S BK26S BK30S
BK03S 0.00
BK05S 0.45 0.00
BK16S 0.46 0.59 0.00
BK21S 0.83 0.95 0.79 0.00
BK25S 0.51 0.68 0.53 0.73 0.00
BK26S 0.57 0.67 0.65 0.76 0.63 0.00
BK30S 0.54 0.67 0.62 0.82 0.57 0.60 0.00
0 <= SCORE <= 1 0: Sample are iden/cal 1: Samples do not share any OTUs
Pairwise Bray-Curtis dissimilarity matrix based on eukaryotic OTU frequencies
BK05S BK16S BK21S BK22S BK25S BK26S BK30S
BK05S 0.00
BK16S 0.62 0.00
BK21S 0.87 0.79 0.00
BK22S 0.94 0.93 0.92 0.00
BK25S 0.69 0.68 0.82 0.89 0.00
BK26S 0.87 0.88 0.92 1.00 0.76 0.00
BK30S 0.98 0.97 0.97 1.00 0.85 0.81 0.00
Bacterial diversity
Pairwise Bray-Curtis dissimilarity matrix based on bacterial OTU frequencies
BK03S BK05S BK16S BK21S BK25S BK26S BK30S
BK03S 0.00
BK05S 0.48 0.00
BK16S 0.50 0.64 0.00
BK21S 0.72 0.86 0.68 0.00
BK25S 0.47 0.63 0.58 0.73 0.00
BK26S 0.54 0.72 0.58 0.61 0.62 0.00
BK30S 0.59 0.79 0.68 0.67 0.64 0.51 0.00
0 <= SCORE <= 1 0: Sample are identical 1: Samples do not share any OTUs
0 <= SCORE <= 1 0: Sample are iden/cal 1: Samples do not share any OTUs
As big as Belgium and 1.5 times bigger than the Emilia-Romagna region in Italy, Lake Baikal is the world’s deepest and largest
(by volume) freshwater lake (Fig1). Baikal formed in an ancient rift valley in Southern Siberia, Russia. The surface of the lake
freezes during winter and its water has a permanent average temperature of ca. 4°C below the surface layers. While planktonic
microorganisms have been studied by microscopy and are currently being studied by molecular approaches, the microbial
diversity associated to the deepest sediments of the lake is virtually unknown, except for one study focusing on methane
hydrates. In order to assess the microbial diversity in Lake Baikal deep sediments, we collected sediment samples in July 2017
(Pictures1&2) along the lake at depths from 323 m to 1450 m. After DNA extraction, we amplified by PCR 16S and 18S rRNA
gene fragments using specific primers for prokaryotes (both archaea and bacteria) and eukaryotes. After tagging and pooling,
amplicons were massively sequenced by paired-end Illumina MiSeq (metabarcoding). We analyzed the sequences in a home-
made metabarcoding pipeline.
Fig1
Picture 1: the scienYfic boat Picture 2: the core tube
15,384 OTUs
4116 OTUs
Same large archaeal groups
but different OTU
composi/on
High diversity of
Woesearchaeota
BK05S and BK21S are the
only samples sharing a Bray-
Cur/s index > 0.9
4196 OTUs
Contrasted qualitative and
quantitative distribution of
eukaryotic OTUs among
samples
BK30S has a very large
number of OTUs especially in
SAR clade
According to our preliminary results, we have showed
in the Baikal sediments:
An unexpected diversity of Woesearchaeota
High heterogeneity between samples for eukaryo/c OTUs
An extremely large diversity of bacterial OTUs
TO BE CONTINUED…
BK30S
BK26S
BK25S
BK22S
BK21S
BK16S
BK05S
BK30S
BK26S
BK25S
BK21S
BK16S
BK05S
BK03S