Contrasting the Genetic Patterns of Microbial Communities in Soda Lakes with and without Cyanobacterial Bloom.

Ana P D Andreote,Ary T Rezende-Filho,Marli F Fiore,Laurent Barbiero,Bruno C E Souza,Gabriela Silva Machineski,Janaina Rigonato,Francisco Dini-Andreote

doi:10.3389/fmicb.2018.00244

Ana P D Andreote, Ary T Rezende-Filho + Show 6 more

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https://doi.org/10.3389/fmicb.2018.00244

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Abstract

Soda lakes have high levels of sodium carbonates and are characterized by salinity and elevated pH. These ecosystems are found across Africa, Europe, Asia, Australia, North, Central, and South America. Particularly in Brazil, the Pantanal region has a series of hundreds of shallow soda lakes (ca. 600) potentially colonized by a diverse haloalkaliphilic microbial community. Biological information of these systems is still elusive, in particular data on the description of the main taxa involved in the biogeochemical cycling of life-important elements. Here, we used metagenomic sequencing to contrast the composition and functional patterns of the microbial communities of two distinct soda lakes from the sub-region Nhecolândia, state of Mato Grosso do Sul, Brazil. These two lakes differ by permanent cyanobacterial blooms (Salina Verde, green-water lake) and by no record of cyanobacterial blooms (Salina Preta, black-water lake). The dominant bacterial species in the Salina Verde bloom was Anabaenopsis elenkinii. This cyanobacterium altered local abiotic parameters such as pH, turbidity, and dissolved oxygen and consequently the overall structure of the microbial community. In Salina Preta, the microbial community had a more structured taxonomic profile. Therefore, the distribution of metabolic functions in Salina Preta community encompassed a large number of taxa, whereas, in Salina Verde, the functional potential was restrained across a specific set of taxa. Distinct signatures in the abundance of genes associated with the cycling of carbon, nitrogen, and sulfur were found. Interestingly, genes linked to arsenic resistance metabolism were present at higher abundance in Salina Verde and they were associated with the cyanobacterial bloom. Collectively, this study advances fundamental knowledge on the composition and genetic potential of microbial communities inhabiting tropical soda lakes.

Highlights

Soda lakes are characterized by elevated levels of pH and NaHCO3 that result in saline and hypersaline alkaline waters
Taking into account that the lakes were sampled during the dry season, that is, when the water level was low, the water temperature and conductivity increased along the sampling day in both lakes
The cyanobacterial bloom observed in Salina Verde was associated with the proliferation of the species A. elenkinii

Summary

Introduction

Soda lakes are characterized by elevated levels of pH and NaHCO3 that result in saline and hypersaline alkaline waters. These ecosystems have been described worldwide, including the East African Rift Valley (Jones et al, 1977; Eugster and Jones, 1979; Ventosa and Arahal, 1989; Duarte et al, 2012), the North and Central Americas (Domagalski et al, 1989; Kazmierczak et al, 2011), Asia (Ma and Edmunds, 2006; Namsaraev et al, 2015), Australia (Hammer, 1986), and Europe (Felföldi et al, 2009; Stenger-Kovács et al, 2014).

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