The Polyextreme Ecosystem, Salar de Huasco at the Chilean Altiplano of the Atacama Desert Houses Diverse Streptomyces spp. with Promising Pharmaceutical Potentials

Abstract

Salar de Huasco at the Chilean Altiplano of the Atacama Desert is considered a polyextreme environment, where solar radiation, salinity and aridity are extremely high and occur simultaneously. In this study, a total of 76 bacterial isolates were discovered from soil samples collected at two different sites in the east shoreline of Salar de Huasco, including H0 (base camp next to freshwater stream in the north part) and H6 (saline soils in the south part). All isolated bacteria were preliminarily identified using some of their phenotypic and genotypic data into the genera Streptomyces (86%), Nocardiopsis (9%), Micromonospora (3%), Bacillus (1%), and Pseudomonas (1%). Streptomyces was found dominantly in both sites (H0 = 19 isolates and H6 = 46 isolates), while the other genera were found only in site H0 (11 isolates). Based on the genotypic and phylogenetic analyses using the 16S rRNA gene sequences of all Streptomyces isolates, 18% (12 isolates) revealed <98.7% identity of the gene sequences compared to those in the publicly available databases and were determined as highly possibly novel species. Further studies suggested that many Streptomyces isolates possess the nonribosomal peptide synthetases-coding gene, and some of which could inhibit growth of at least two test microbes (i.e., Gram-positive and Gram-negative bacteria and fungi) and showed also the cytotoxicity against hepatocellular carcinoma and or mouse fibroblast cell lines. The antimicrobial activity and cytotoxicity of these Streptomyces isolates were highly dependent upon the nutrients used for their cultivation. Moreover, the HPLC-UV-MS profiles of metabolites produced by the selected Streptomyces isolates unveiled apparent differences when compared to the public database of existing natural products. With our findings, the polyextreme environments like Salar de Huasco are promising sources for exploring novel and valuable bacteria with pharmaceutical potentials.

Living to the High Extreme: Unraveling the Composition, Structure, and Functional Insights of Bacterial Communities Thriving in the Arsenic-Rich Salar de Huasco Altiplanic Ecosystem

“…1 ) ( 8 ), which is consistent with the widely reported heterogeneity for this area and the potential impact of such an extreme condition over the resident organisms ( 29 ). Previous studies have detected variations in conductivity, organic matter, and dissolved oxygen, even in geographically close areas ( 5 , 6 , 30 – 32 ). In aquatic ecosystems, the quantity of trace elements and physicochemical states of some elements are related to their circulation/interaction and with the coping mechanisms of the organisms present ( 33 ).…”

Genomic Variation and Arsenic Tolerance Emerged as Niche Specific Adaptations by Different Exiguobacterium Strains Isolated From the Extreme Salar de Huasco Environment in Chilean – Altiplano

“…Altiplanic environments have extreme and variating conditions, even between geographically close areas (Cabrol et al, 2009a;Hernández et al, 2016;Cortés-Albayay et al, 2019). Particularly, a previous work in SH showed highly different values of conductivity, dissolved nitrogen and dissolved organic carbon, between two ponds just a few meters apart (Aguilar et al, 2016).…”

“…The Salar de Huasco is a poly-extreme ecosystem located on the Chilean Altiplano (Northern Region) where cultivable members of the Exiguobacterium genus are ubiquitous ( Remonsellez et al, 2018 ). This area is subjected to major climatic oscillations ( Cortés-Albayay et al, 2019 ), namely: temperature, salinity, high levels of solar radiation, negative water balance and the presence of arsenic ( Dorador et al, 2008 ; Herrera et al, 2009 ; Hernández et al, 2016 ; Pérez et al, 2017 ; Remonsellez et al, 2018 ; Castro-Severyn et al, 2019 ). Another relevant aspect of the Salar de Huasco is the great microbial diversity that has been little explored ( Dorador et al, 2010 , 2013 ; Molina et al, 2016 ; Castro-Severyn et al, 2017 ).…”

Evaluation of antimicrobial and antiproliferative activities of Actinobacteria isolated from the saline lagoons of northwestern Peru

“…In this study, isolation was performed using three types of culture media and four different concentrations of salt in the lagoons because the concentration of salts ranged from 0 to 300 psu. Cortés-Albayay et al (2019) in Salar de Huasco reported similar results; they isolated Streptomyces (86%), Nocardiopsis , (9%), Micromonospora (3%), Bacillu s (1%), and Pseudomonas (1%) [ 44 ].…”