Mikiko Tsudome

Preparation and characterisation of nanofibrous cellulose plate as a new solid support for microbial culture

Porous plates made of nanofibrous crystalline cellulose were prepared, and used as a solid support for microbial cultures. Representative mesophilic microorganisms (, , and ) grew on the cellulose plate, just as well as they did on the conventional agar plate. optical microscopic examination revealed that the cellulose plate remained unchanged up to 280 °C at a constant pressure of 25 MPa. Due to the structural stability at high temperatures, a representative thermophile, , was cultured successfully on the cellulose plate at 80 °C. Mouse fibroblast cells did not show significant adhesion or extension on the cellulose plate.

Microbial growth at hyperaccelerations up to 403,627 × g

It is well known that prokaryotic life can withstand extremes of temperature, pH, pressure, and radiation. Little is known about the proliferation of prokaryotic life under conditions of hyperacceleration attributable to extreme gravity, however. We found that living organisms can be surprisingly proliferative during hyperacceleration. In tests reported here, a variety of microorganisms, including Gram-negative Escherichia coli, Paracoccus denitrificans, and Shewanella amazonensis; Gram-positive Lactobacillus delbrueckii; and eukaryotic Saccharomyces cerevisiae, were cultured while being subjected to hyperaccelerative conditions. We observed and quantified robust cellular growth in these cultures across a wide range of hyperacceleration values. Most notably, the organisms P. denitrificans and E. coli were able to proliferate even at 403,627 × g. Analysis shows that the small size of prokaryotic cells is essential for their proliferation under conditions of hyperacceleration. Our results indicate that microorganisms cannot only survive during hyperacceleration but can display such robust proliferative behavior that the habitability of extraterrestrial environments must not be limited by gravity.

Versatile Solidified Nanofibrous Cellulose-Containing Media for Growth of Extremophiles

ABSTRACT Solidified media that employ a porous matrix of nanofibrous cellulose are described. The physicochemical stability of the porous structure allows the development of solidified media that can support the growth of extremophiles, such as acidophilic Acidiphilium, alkaliphilic Bacillus, thermophilic Geobacillus and Thermus, alkalithermophilic Bacillus, and acidothermophilic Sulfolobus microbes. The cellulose-supported media have several advantages over agar- and gellan gum-derived media, including versatility and stability.