Pristine Ecosystem - an Ecological Approach to Geothermal and Hydrothermal Microbial Mat
Kenji KATO*a, Yonosuke MAKIb, Hiroyuki YAMAMOTOc, Hiroshi CHIURAa, Akira HIRAISHIe, Akira SHIMIZUf, and Katsunori FUJIKURAg
a Laboratory of Biology, School of Allied Medical Sciences, Shinshu University, Matsumoto 390, Japan
b Laboratory of Biology, Faculty of Humanities and Social Sciences, Iwate University, Morioka 020, Japan
c Department of Microbiology, St. Marianna University School of Medicine, Kawasaki 216, Japan
d Department of Biology, Division of Natural Sciences, International Christian University, Mitaka 181, Japan
e Department of Ecological Engineering, Toyohashi University of Technology, Toyohashi 441, Japan
f Department of Biology, Faculty of Science, Nara Women's University, Nara 630, Japan
g Deep Sea Research Department, JAMSTEC, Yokosuka 237, Japan
Hot spring as well as hydrothermal vent provide extremely, if compared to the majority of the present environment on Earth, thermal environment where ecosystem is constituted of prokaryote alone. These systems may lead us an imaginative world of the early stage of the environmental evolution on Earth ever existed. The big difference between these two is that hot spring is independent from the surroundings, while hydrothermal vent is surrounded by massive sea water which has kept various organisms of evolutional history. If the hot water is above 60℃ and contains abundant hydrogen sulfide and low oxygen below 1 ppm with neutral pH, a milky white filament like grass, which is named “sulfur-turf”, is found in many distant hot springs in Japan. The constituent bacteria of sulfur-turf and an existence of viruses_like particles (VLPs) with potential activity of gene transfer are shown in this Congress (presented by Yamamoto et al. and Chiura et al.). We regard this kind of system a pristine ecosystem which might exist in the world before eukaryotes appeared. Ecological aspect to study these exciting fields is discussed.
