A Molecular View of Microbial Diversity in Marine and Terrestrial Hot Water Environments
Ken TAKAI*a,b, Takuro NUNOURAb, Yoshihiko SAKOb, and Aritsune UCHIDAb
a The DEEPSTAR group, Japan Marine Science and Technology Center, 2-15 Natsushima- cho, Yokosuka 237, Japan
b Laboratory of Marine Microbiology, Department of Applied Bioscience, Graduate School of Agriculture, Kyoto University, Kyoto 606-01, Japan
Isolation and cultivation of extremely thermophilic or hyperthermophilic microorganisms have contributed to our knowledge about the presence and diversity of microbes capable of growing at extraordinary temperatures and about their novel biochemical machinery. However, molecular phylogenetic surveys of naturally occurring microbial community in Yellowstone National Park hot spring environments indicate that the phylogenetic diversity of thermophilic microorganisms is far greater than previously proposed by such methods (1, 2). Here we report the further phylogenetic characterization of diverse microbial community in hot water environments by the PCR-mediated small subunit rRNA gene (SSU rDNA) sequencing. The mixed population DNA is directly extracted from the effluent hot water or sediment of a shallow marine hydrothermal vent at Tachibana Bay, or the acidic hot water of hot spring pools at Mr. Unzen, in Nagasaki Prefecture, Japan. Based on the partial rDNA sequences amplified with Bacteria-, Archaea-specific or universal primers, the microbial populations of hot water environments consisted of phylogenetically and physiologically diverse group of microorganisms. The microbial population are varied in each sample and subject to its environmental conditions. In addition, the large number of bacterial or archaeal rDNA sequences recovered from hot water environments are the uncultivated and unidentified types of sequences and reveal distant relationship not only to the cultivated species but also to the unidentified species found in a Yellowstone National Park hot spring. The findings extend our view of microbial diversity in hot water environments and phylogenetic organization of these organisms.
1. Barns, S.M., Fundyga, R.E., Jeffries, M.W., and Pace N.R. (1994) Proc. Natl. Acad. Sci. USA, 91, 1609-1613.
2. Reysenbach, A.-L., Wichham, G.S., and Pace, N.R. (1994) Appl. Environ. Microbiol., 60, 2113-2119.
