Poster Presentation Australian Microbial Ecology 2022

Perchlorate tolerant halophile isolated from analogous Martian environment (#121)

Cameron Lee 1 , Anthony Greene 1
  1. School of Environment and Science, Griffith University, Brisbane, QLD, Australia

Extreme environments are highly diverse and abundant environments, with resident organisms not only capable of surviving, but thriving at conditions complex organisms would find detrimental. Spotted Lake, British Columbia, Canada is a hypersaline lake that shares similar conditions presumed to be associated with ancient Mars. Isolation and identification of novel organisms from extreme environments has vastly increased the knowledge and understanding of how organisms adapt, survive and metabolise in extreme conditions. Halophilic organisms are salt-loving organisms capable of growth in salt concentrations of 3-30% NaCl (w/v)[1], making them extremely diverse in ocean waters, saline lakes and other hypersaline environments[2]. Permanently cold hypersaline environments are found in dry regions of Antarctica including Deep Lake, Lake Suribati and Organic Lake. The halophilic psychrophile Halorubrum lacusprofundi was isolated from Deep Lake; and despite surface temperatures of -20oC, the water doesn’t freeze due to near salinity saturation[3]. Halophiles have evolved two distinctive strategies to generate a hyperosmotic cytoplasm and maintain a positive cell turgor pressure: the “High salt-in” strategy and the “Low-salt, organic solute-in” strategy[4]. Present day Mars is a volatile environment, described as a “cold and dry” planet with little to no surface water activity. Surface temperatures depend on the season and time of day on Mars but can range from -123oC to 25oC (average -61oC)[5]. Researchers have found pockets of surface waters that contain various salts (chlorides, sulphates and perchlorates) with can drop the freezing point to -80oC [6]. Streatham Salt Lake (SSL) is a pink lake located ~200km west of Melbourne, Victoria. The pink water is a result of Dunaliella salina (red algae) growing in the waters. There have been no studies on the waters of SSL. A halophilic isolate (SSL-5) was isolated; it has a salinity tolerance 3 – 25% (Optimum 7 – 11 %). The isolate was resistant up to 5% perchlorate. 16S rRNA analysis indicated SSL-5 was closely related to Halomonas alimentaria YKJ-16 and Halomonas icarae D1-1 (98.42% and 98.30% respectively). However, OrthoANI analysis of SSL-5 against Halomonas alimentaria YKJ-16 and Halomonas icarae D1-1 showed 91.90% and 85.60% respectively, indicating a novel organism. Further studies are required to classify and a novel genus/species. This study can further push the limits of terrestrial life.

 

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