DNA metabarcoding para análise da microbiota aquática em um experimento de mesocosmos
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2024-07-12
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Universidade Federal de Goiás
Resumo
Aquatic microbiota are very important in aquatic environments and perform essential ecosystem
functions, such as nutrient cycling and waste decomposition. A group of organisms that make up
this complex biota is the phytoplankton community. For the phytoplankton community, higher
temperatures and high concentrations of nutrients such as phosphorus can lead to an increase in the
biomass of algae, especially cyanobacteria, reducing biodiversity and impacting the entire aquatic
ecosystem. The use of advanced molecular technologies and techniques, such as DNA
metabarcoding, has enabled greater knowledge about the biodiversity of the aquatic microbiota. In
this study, two rDNA regions were analyzed in order to investigate how temperature rise and
trophic state variation affect the richness and composition of phytoplankton communities of
prokaryotes and microeucariots in mesocosms. We employed various methods to examine these
taxa (OTUs and ASVs) and evaluate the statistical pattern of response across three data sets: Total
OTUs/ASVs, OTUs/ASVs classified in databases, and OTUs/ASVs classified and manually filtered
for the phytoplankton community with the help of scientific articles. The samples were examined
from a mesocosm experiment where various temperature and trophic state conditions were
simulated. The DNA was extracted and quantified and the 16S V3-V4 and 18S V4 rDNA regions
were amplified to access prokaryotic and eukaryotic organisms respectively. The amplified products
were prepared and sequenced on the Illumina MiSeq platform using the 600-cycle Illumina MiSeq
kit. In bioinformatics analyses, we follow the PIMBA pipeline for the identification and
classification of OTUs and ASVs. A manual inspection was performed to filter the OTUs and ASVs
belonging to the phytoplankton. We conducted an ANOVA and PERMANOVA to evaluate the
richness and composition of OTUs and ASVs under different treatments. It was observed that there
were differences in the results obtained for OTUs and ASVs in certain cases. However, we noticed
that ASVs generate an inflation in the results of wealth and composition. This leads us to conclude
that the OTUs approach is more appropriate when the objective is to approach the species level to
evaluate aquatic microbiota communities. Our findings showed that the increase in nutrient load
was harmful to richness, as it encourages the selection of specific organisms that are more suited to
eutrophic environments, which, in turn, affects the composition and structure of the community of
prokaryotes and phytoplankton eukaryotes. The richness and composition of OTUs and ASVs for
cyanobacteria were not significantly altered by the temperature range between 25 °C and 28 °C,
suggesting that the species present are well adapted to this temperature variability. For
microeucariots, temperature had a positive influence on OTUs richness and no influence on ASVs
richness.Temperature did not have any impact on the composition of OTUs between treatments, but
the complex relationship between temperature and nutrients was crucial to distinguish these
communities. In general, we saw that eutrophication was more harmful to phytoplankton
communities than the increase in temperature at 3ºC.
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Palavras-chave
Ecologia de comunidades, EDNA, Mudanças climáticas, 18S rDNA, 16S rDNA, Community ecology, Climate change
Citação
MARTINS, Beatriz Barbosa Araújo. DNA metabarcoding para análise da microbiota aquática em um experimento de mesocosmos. 2024. 62 f. Trabalho de Conclusão
de Curso (Bacharelado em Ecologia e Análise Ambiental) - Instituto de Ciências Biológicas, Universidade Federal de Goiás, Goiânia, 2024.