Benthic Bacterial Diversity of High-Altitude Athalassohaline Lakes of the Puna de Atacama (Central Andes)

Abstract

High-altitude saline lakes (located more than 3000 m a.s.l.) provide multiple environmental extremities for polyextremophilic bacteria. In this study, lake sediment samples from Laguna Santa Rosa and microbial mat samples from the warm water pool of Laguna Verde (Puna de Atacama, Chile) were examined by cultivation and pyrosequencing. The 16S rRNA gene-based identification showed that most of the bacterial isolates belonged to different moderately halophilic Marinobacter species (Proteobacteria). Sample-specific occurrence was characteristic of genera Caenispirillum, Halomonas, Idiomarina, Nitratireductor and Salinarimonas (Proteobacteria), Planococcus, Jeotgalibacillus and Paraliobacillus (Firmicutes), Psychroflexus (Bacteroidetes) and Arthrobacter (Actinobacteria). Using cultivation-independent technique, the benthic communities of both lakes were dominated by sequences related to the phyla Proteobacteria and Bacteroidetes. In addition, representatives of phyla Actinobacteria, Chlorobi, Chloroflexi, Cloacimonetes, Cyanobacteria, Deferribacteres, Deinococcus-Thermus, Firmicutes, Gracilibacteria, Latescibacteria, Lentisphaerae, Parcubacteria, Planctomycetes, Spirochaetae, Tenericutes and Verrucomicrobia were present at least 1% relative abundance. Large differences were explored in the bacterial community composition of the sediment and mat samples at the level of the identified families. It is hypothesized that depending on the type of benthic habitat, different bacteria – involved in the phototrophy based primary production as well as the mainly anaerobic biodegradation of organic materials – can participate in the local carbon, nitrogen, and sulfur cycles.