Comparison of prokaryotic community structure from Mediterranean and Atlantic saltern concentrator ponds by a metagenomic approach.

Ana B Fernã¡Ndez,Francisco Rodriguez-Valera,Rohit Ghai,R Thane Papke,Antonio Ventosa,Cristina Sã¡Nchez-Porro,Blanca Vera-Gargallo

doi:10.3389/fmicb.2014.00196

Ana B Fernã¡Ndez, Francisco Rodriguez-Valera + Show 5 more

Open Access

https://doi.org/10.3389/fmicb.2014.00196

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Abstract

We analyzed the prokaryotic community structure of a saltern pond with 21% total salts located in Isla Cristina, Huelva, Southwest Spain, close to the Atlantic ocean coast. For this purpose, we constructed a metagenome (designated as IC21) obtained by pyrosequencing consisting of 486 Mb with an average read length of 397 bp and compared it with other metagenomic datasets obtained from ponds with 19, 33, and 37% total salts acquired from Santa Pola marine saltern, located in Alicante, East Spain, on the Mediterranean coast. Although the salinity in IC21 is closer to the pond with 19% total salts from Santa Pola saltern (designated as SS19), IC21 is more similar at higher taxonomic levels to the pond with 33% total salts from Santa Pola saltern (designated as SS33), since both are predominated by the phylum Euryarchaeota. However, there are significant differences at lower taxonomic levels where most sequences were related to the genus Halorubrum in IC21 and to Haloquadratum in SS33. Within the Bacteroidetes, the genus Psychroflexus is the most abundant in IC21 while Salinibacter dominates in SS33. Sequences related to bacteriorhodopsins and halorhodopsins correlate with the abundance of Haloquadratum in Santa Pola SS19 to SS33 and of Halorubrum in Isla Cristina IC21 dataset, respectively. Differences in composition might be attributed to local ecological conditions since IC21 showed a decrease in the number of sequences related to the synthesis of compatible solutes and in the utilization of phosphonate.

Highlights

Hypersaline habitats are characterized by high salt concentrations, in addition to other features, such as high or low temperatures, high pH, and/or low oxygen concentrations (Javor, 1989; Rodríguez-Valera, 1993)
The salinity in IC21 is closer to the pond with 19% total salts from Santa Pola saltern, IC21 is more similar at higher taxonomic levels to the pond with 33% total salts from Santa Pola saltern, since both are predominated by the phylum Euryarchaeota
In IC21 the low G+C peak is shifted to a value slightly higher than that observed in metagenomic datasets from Santa Pola ponds, SS19 and SS33, around 51–52%

Summary

Introduction

Hypersaline habitats are characterized by high salt concentrations, in addition to other features, such as high or low temperatures, high pH, and/or low oxygen concentrations (Javor, 1989; Rodríguez-Valera, 1993). Most saltern studies have been performed on the saturated brine crystallizer ponds (Antón et al, 1999, 2000; Benlloch et al, 2001; Pašicet al., 2005; Pasicet al., 2007; Legault et al, 2006; Oh et al, 2010). Most bacterial sequences in the 8% salt pond were related to organisms of marine origin belonging to representatives of the classes Alpha-, Beta-, Gamma-, and EpsilonProteobacteria, and the phyla Bacteroidetes, Actinobacteria, and Cyanobacteria. From the 32% salt pond, the only Bacteria found were sequences that clustered with Salinibacter ruber, an extremely halophilic Bacteroidetes. In those three different salinity ponds, most of the clones were related to cultured strains of the archaeal www.frontiersin.org

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