Abstract
We evaluated biological activities in terrestrial extreme environment samples from Antarctica soils and submarine hydrothermal systems by measuring phosphatase activities. The soil of Site 8 (near a penguin rookery) showed almost the same level of phosphatase activities as usual surface soil sampled in Yokohama National University (YNU ) campus, while the soil of the other stations showed much less activities. Massive sulfide chimneys of submarine hydrothermal vents in South Mariana Backarc also showed phosphatase activities: The exterior part of the chimnies showed higher than the interior part, suggesting the prokarotic habitat and cell density. Alkaline phosphatase (ALP) in the extracts from the soil of Antarctica Site 8 and chimney samples was characterized by the laboratory-based enzymatic assessments. Among these profiles, firstly, the Antarctica ALP showed the maximal at 37℃, the chimney ALP showed the maximal at 90℃, while ALP from the YNU soil showed the maximal at 60℃. Secondly, the gel filtration chromatography showed that the ALP activity in both Antarctica and chimney samples was found mainly in the fraction whose molecular weights were around 100000 Dalton. The ALP activity was diminished with EDTA and was recovered with addition of zinc ion. The present results showed that zinc-containing metalloenzymes are present in the Antarctica soils and the chimneys in the hydrothermal system, and that phosphatases are useful bio-signatures for extant life in extreme environments. Phosphatase activity could be used for life detection in extraterrestrial environments, as well as for evaluation of biochemical function of prebiotic samples.
