| Autor: |
Nami, Matsumoto, Hiromi, Hattori, Minenosuke, Matsutani, Chihiro, Matayoshi, Hirohide, Toyama, Naoya, Kataoka, Toshiharu, Yakushi, Kazunobu, Matsushita |
| Rok vydání: |
2018 |
| Předmět: |
|
| Zdroj: |
Applied and environmental microbiology. 84(10) |
| ISSN: |
1098-5336 |
| Popis: |
Thermotolerant microorganisms are beneficial to the fermentation industry because they reduce the need for cooling and offer other operational advantages. Previously, we obtained a thermally adapted Gluconobacter frateurii strain by experimental evolution. In the present study, we found only a single G insertion in the adapted strain, which causes a frameshift in a gene encoding a putative drug transporter. A mutant derivative strain with the single G insertion in the transporter gene (Wild-G) was constructed from the wild-type strain and showed increased thermotolerance. We found that the thermotolerant strains accumulated substantial intracellular trehalose and manifested a defect in sorbose assimilation, suggesting that the transporter is partly involved in trehalose efflux and sorbose uptake and that the defect in the transporter can improve thermotolerance. The ΔotsAB strain, constructed by elimination of the trehalose synthesis gene in the wild type, showed no trehalose production but, unexpectedly, much better growth than the adapted strain at high temperatures. The ΔotsAB mutant produced more acetate as the final metabolite than the wild-type strain did. We hypothesized that trehalose does not contribute to thermotolerance directly; rather, a metabolic change including increased carbon flux to the pentose phosphate pathway may be the key factor. The NADPH/NADP+ ratio was higher in strain Wild-G, and much higher in the ΔotsAB strain, than in the wild-type strain. Levels of reactive oxygen species (ROS) were lower in the thermotolerant strains. We propose that the defect of the transporter causes the metabolic flux to generate more NADPH, which may enhance thermotolerance in G. frateurii. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
|
