Variation of Cell Shapes of an Acidothermophilic Archaebacterium Thermoplasma Strains
Akihiko YAMAGISHI*a, Megumi INUGAMIa, Naoya SHINZATOa, Tairo OSHIMAa, and Gen TAKAHASHIb
a Department of Molecular Biology, Tokyo University of Pharmacy and Life Science, 1432-1 Horinouchi, Hachioji, Tokyo 192-03, Japan
b School of Medicine, Hirosaki University, 5 Zaifucho, Hirosaki 036, Japan
We have previously isolated several new strains of Thermoplasma acidophilum from Japanese hot springs. These strains showed variations in cell structure when inspected by transmission electron microscope: some strains have fibrous structures at the surface of the cells while others do not, some have crystal like structures in the cytoplasm while others do not. We have investigated cellular and giant cellular structures of the strains with an optical and scanning electron microscopes (SEM). Most of the cells of strain HO-51 showed a spherical shape with a smooth surface. Although, rod-like structure with fibrous surface was also seen. Aggregated form of cells are seen especially after prolonged incubation of the culture. In addition to the aggregated spherical cells, three dimensional net like structure made of short rods was also observed by SEM.
Another strain HO-121 showed cells of iregular shape, which is rather characteristic to the type strain of Thermoplasma acidophilum.
Cells of HO-12 had spherical surface with knobs. Three dimensional net-like structure made of spherical cells and rods was also seen.
Cells of HO-54 were spherical when they are in a single form. Although the cells tend to form macro cells with large dimension. The DAPI stained cells showed particles in aggregated form of cells suggesting the presence of individual chromosome of each cell in the aggregate. On the other hand, dispersed continuous staining was observed in the macro cells suggesting that individual cells can not be identifiable within the macro cells.
