Archaea Isolates from five hypersaline environments in Argentinean Puna

Abstract

The objective of this study was isolate and study halophilic archaea in five hypersaline environments from the Argentinean Puna. Puna is a unique natural area covering northern Chile, western Bolivia, central and southern Peru and north-western Argentina (NOA). These environments are characterized by extreme conditions where salt concentration is very high, near saturation (up to 4 M or 25%), low oxygen tension, large daily air temperature fluctuations, ranging from 20°C during the day to −40°C at night, high UV incidence, high arsenic concentrations and oligotrophy. There is not much information about halophilic archaea in Argentina. The water samples were collected from five different wetlands: Antofalla lake (Catamarca), Socompa lake (Salta), Tolar Grande “Sea eye” (Salta), Pocitos salt flat (Salta) and Llullaillaco salt flat (Salta). These lakes are located above 3500 masl. The samples were cultivated in 6 ws medium for 7 days at 37ºC. 32 strains were isolates. The isolates corresponded to genera Halorubrum, Haloarcula and Halomicrobium. Pigments from the isolates were extracted with methanol. The identification of pigments was based on absorbance spectra. The absorbance was measured at wavelength range 200-800 nm. The most were carotenoids pigments with the highest absorption peak at 492 nm. Plasmid DNA was isolated by using a modified method of Anderson and McKay and the QIAprep® Spin Miniprep Kit (QIAGEN). Ten of the isolates contain plasmids with sizes ranging from 1.5 kb to 5 kb approximately. The presence of plasmids in Archaea from hypersaline environments apparently is a widespread phenomenon. For UV resistance qualitative analysis were plated 5 ul of dilutions between 10-1 and 10-7 in drop form, on 1.5% agar (w/v). The plates were exposed 1 to 13 hours to UV – B light. Then the plates were incubated inverted for 7 days at 37 °C. All the strain had resistance to UV - B light.