論文の公開元へEnhancement of ethanol production and cell growth in budding yeast by direct irradiation of low-temperature plasma
概要
Low-temperature plasma (LTP) has been widely used for medicine and agriculture1-7). Indirect plasma treatments such as plasma-activated medium (PAM) as well as direct plasma treatments have broadened the ways to apply the LTP8-11). Since reaction products among LTP and solutions play some roles on physiological responses, indirect plasma treatments are important, however, the effects by UV/VUV and direct interactions between short-lived reactive species and biological surface are brought by direct plasma treatments. Thus, it is essential to investigate effects by both direct and indirect plasma irradiations.
The budding yeast (Saccharomyces cerevisiae) is an important eukaryotic model organism with well-developed genetics and molecular biology12-14). The effects of LTP on budding yeast have been investigated to understand molecular mechanisms common to eukaryotic cells15-20). For example, Hashizume et al., showed that the growth of budding yeasts’ cells was regulated primarily in response to the total dose of oxygen atoms17). LTP induces apoptosis through reactive oxygen species (ROS) on budding yeast cells as well as mammalian cells18). There are two superoxide dismutases in budding yeast: Sod1p and Sod2p. Increased LTP resistance was observed in strains overexpressing SOD1 or SOD218). On the other hand, increased LTP sensitivity was observed in strains deleting SOD1 or SOD219). These results suggest that ROS generated by LTP are prominent factor in killing of budding yeasts. In addition to studies in basic science, budding yeast has been used in fermentation processes for making bioethanol21-24). LTP might be useful to improve the production of bioethanol by budding yeast25).
In this study, we investigated ethanol production of budding yeast treated with LTP directly and plasma-activated medium (PAM). The ethanol production was increased not by PAM but by direct plasma irradiation. We further demonstrated glucose consumption and glycolytic activity were increased by direct plasma irradiation of budding yeast cells. These results suggest that LTP is a promising strategy for producing bioethanol.
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