Characterization of R. taiwanensis MD1149. Light microscopy of liquid overnight culture of MD1149 grown (A) without chronic ionizing radiation and (B) under 36 Gy/h (137Cs). Scale bars: 5 μm. Source: Uniformed Services University of the Health SciencesThe production of 46,000 nuclear weapons in the U.S. during 1945-1986 generated large volumes of acidic radioactive waste. Stored in subterranean holding tanks or ponds, these legacy wastes have resulted in low levels of widespread contamination. Bioremediation schemes are usually effective in decontaminating radioactive waste, but bacteria-based techniques are not applicable to media with pH values below 4.8.

A yeast species discovered by Uniformed Services University of the Health Sciences researchers that was found to be extremely resistant to acute and chronic forms of gamma radiation, heavy metals and acid could form the basis of a safer, more efficient bioremediation route. Rhodotorula taiwanensis MD1149 was demonstrated to grow and remain viable under 66 Gy/h at pH 2.3 and in the presence of high concentrations of mercury and chromium compounds.

The proposed use of MD1149 and other fungi for treatment of environments where radiation, low pH and heavy metals are the principal factors limiting microbial survival and function appears to be a realistic approach given these early data.

The research is published in the journal Frontiers in Microbiology.