Survey of Genomes - Deinococcus radiodurans

Genomics Revolution

Content provided by Hiram College Podcasting and Brad Goodner. All podcast content including episodes, graphics, and podcast descriptions are uploaded and provided directly by Hiram College Podcasting and Brad Goodner or their podcast platform partner. If you believe someone is using your copyrighted work without your permission, you can follow the process outlined here https://podcastplayer.com/legal.

6y ago 4:59

MP3•Episode home

Welcome to Genomics Revolution! My name is Nicole Ryman and I will be hosting this episode to discuss the genome of a bacterium with a Guinness World Record! Deinococcus radiodurans claimed the record for “Most radiation-resistant lifeform” by being capable of withstanding 1.5 million rads of gamma radiation, which is about 3,000 times the lethal amount to kill a human. The bacterium is capable of not only surviving, but also reproducing in environments that would be lethal for any other organism. Deinococcus radiodurans R1 was the first strain of deinobacteria to be discovered by Arthur W. Anderson in 1956 after observing red bacteria in spoiled canned meat after being exposed to radiation (White, et al. 1999).

The secret to this bacteria’s profound resistance to extreme conditions? It’s multi-genomic structure! The D. radiodurans R1 genome is composed of two chromosomes, ranging in size between 2.65 Mbp and 412 kbp, one megaplasmid of 177 kbp, and one small plasmid of 46 kbp (Hau et al. 2017). Overall, the genome encodes about 3,195 predicted genes. The bacterium carries between four and ten copies of its genome, rather than the usual single copy. The additional genomes seem to allow the bacterium to recover at least one complete copy of its genome after exposure to extreme conditions such as radiation, oxidation, desiccation, or UV light without dying or undergoing induced mutation (Eggington et al. 2004).

A combination of factors has positioned D. radiodurans as a promising candidate for the study of mechanisms of DNA damage and repair, as well as developing beneficial operations for toxic waste cleanup and stabilization of radioactive waste sites. The D. radiodurans sequencing project was funded by the US Department of Energy (DOE), which is interested in using the bacterium in environmental cleanup. DOE is responsible for multiple radioactive waste sites around the country, some of which are contaminated with heavy metals and toxic chemicals. Researchers have produced new strains of the bacterium to detoxify toxic waste sites which contain radioactive material (Brim et. al 2000).

Within the United States, radioactive wastes have contaminated millions of cubic yards of soil and trillions of gallons of ground water. Researchers have engineered multiple strains of D. radiodurans to convert heavy metals, organic and inorganic chemicals found in radioactive waste sites into a much less toxic form. These genetically engineered strains may not be able to completely dispose of the radiation, but they may accelerate the cleanup process and save money (Brim et al., 2006). Meanwhile, scientists are also pursuing more “out of this world” opportunities of D. radiodurans—outer space. The organism could be used in simulations to help scientists predict where to search for life on Mars and other planets. In addition, researchers suggest further potential uses of D. radiodurans in space. The bacterium could pose a use for space travel sewage treatment processes or in environmental engineering to make the surface more suitable for human colonization (Leuko et al. 2017).

Supposedly, there is no environment on Earth that exposes life to more than a fraction of the amount of radiation this bacterium can withstand. Since this bacterium is often isolated from extreme environments where severe conditions of temperature, pH, salts, or toxic compounds are present, genome analyzation offers the opportunity to understand how cells are able to exist and restore damaged chromosomal DNA in harsh conditions. Clearly this bacterium’s remarkable capabilities of cleaning up toxic waste, exploring extreme environments, and engineering new processes, should be continually studied for society’s benefit. Understanding the substantial endurance of D. radiodurans of extreme physical, chemical, and biological conditions opens up a field of indefinite possibilities… maybe anything is possible after all. Thanks for listening.

References:

Brim, H., S. McFarlan, J. Fredrickson, K. Minton, M. Zhai, L. Wackett, and M. Daly. 2000. Engineering Deinococcus radiodurans for metal remediation in radioactive mixed waste environments. Nature biotechnology 18: 85-90.

Brim, H., et al. 2006. Deinococcus radiodurans engineered for complete toluene degradation facilitates Cr(VI) reduction. Microbiology 152: 2469-2477.

Eggington, J., N. Haruta, E. Wood, and M. Cox. 2004. The single-stranded DNA-binding protein of Deinococcus radiodurans. BMC Microbiology 4: 1–12.

Hau, X., Y. Hua. 2016. Improved complete genome sequence of the extremely radioresistant bacterium Deinococcus radiodurans R1 obtained using PacBio single-molecule sequencing. American Society for Microbiology 4: 1-2.

Leuko, S., et al. 2017. On the stability of Deinoxanthin exposed to Mars conditions during a long-term space mission and implications for biomarker detection on other planets. Frontiers in microbiology 8: 1-11.

White, O., et al. 1999. Genome sequence of the radioresistant bacterium Deinococcus radiodurans R1. Science 286: 1571-1577.

58 episodes

#Science #Podcasting Education #Natural Sciences #Hiram College #Brad Goodner #Genomics #Dna Sequencing