Prospects for Fungal Bioremediation of Acidic Radioactive Waste Sites: Characterization and Genome Sequence of Rhodotorula taiwanensis MD1149
“Highly concentrated radionuclide waste produced during the Cold War era is stored at US Department of Energy (DOE) production sites. This radioactive waste was often highly acidic and mixed with heavy metals, and has been leaking into the environment since the 1950s. Because of the danger and expense of cleanup of such radioactive sites by physicochemical processes, in situbioremediation methods are being developed for cleanup of contaminated ground and groundwater. To date, the most developed microbial treatment proposed for high-level radioactive sites employs the radiation-resistant bacterium Deinococcus radiodurans. However, the use of Deinococcus spp. and other bacteria is limited by their sensitivity to low pH. We report the characterization of 27 diverse environmental yeasts for their resistance to ionizing radiation (chronic and acute), heavy metals, pH minima, temperature maxima and optima, and their ability to form biofilms. Remarkably, many yeasts are extremely resistant to ionizing radiation and heavy metals. They also excrete carboxylic acids and are exceptionally tolerant to low pH. A special focus is placed on Rhodotorula taiwanensis MD1149, which was the most resistant to acid and gamma radiation. MD1149 is capable of growing under 66 Gy/h at pH 2.3 and in the presence of high concentrations of mercury and chromium compounds, and forming biofilms under high-level chronic radiation and low pH. We present the whole genome sequence and annotation of R. taiwanensis strain MD1149, with a comparison to other Rhodotorula species. This survey elevates yeasts to the frontier of biology’s most radiation-resistant representatives, presenting a strong rationale for a role of fungi in bioremediation of acidic radioactive waste sites.”
Tkavc Rok, Matrosova Vera Y., Grichenko Olga E., GostinÄar Cene, Volpe Robert P., Klimenkova Polina, Gaidamakova Elena K., Zhou Carol E., Stewart Benjamin J., Lyman Mathew G., Malfatti Stephanie A., Rubinfeld Bonnee, Courtot Melanie, Singh Jatinder, Dalgard Clifton L., Hamilton Theron, Frey Kenneth G., Gunde-Cimerman Nina, Dugan Lawrence, Daly Michael J. (2018). Prospects for Fungal Bioremediation of Acidic Radioactive Waste Sites: Characterization and Genome Sequence of Rhodotorula taiwanensis MD1149. Frontiers in Microbiology 8:2528.
I thought this paper would be interesting to look at not only because it deals with fungi, which are not often thought of as microbes, but because of why fungi were chosen. There are distinctive advantages and disadvantages to utilizing different types of microbes in bioremediation, and I think this paper addresses that well. There is also a definite need for something which is able to process the contamination at this site, and bioremediation is an intriguing possibility.