Honors Project

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Biologically, not much is known about the history of the earth for the first three billion years. Some questions such as when the first life appeared on earth and its source remain unanswered.

Before the Great Oxidation Event (GOE), which occurred about 2.45 billion years ago, our Earth’s ozone layer had not yet been formed. Since the ozone layer is useful in shielding life from the harmful UV radiation, phototrophs such as cyanobacteria were affected by the formation of the ozone layer since they required the solar radiation as an input in photosynthesis and other metabolic processes (Codd, Morrison & Metcalf, 2005, p267). However, this also exposed them to lethal UV radiation that can cause direct and indirect damage to the macromolecules such as proteins and DNA of all cellular life in this planet. Since the stratospheric ozone layer came into after the great oxidation event, failure of the event happening would have made microbial life adopt a wide range of strategies to survive under the harsh UV radiation, most probably by producing UV-blocking chemicals also known as microbial sunscreen compounds. In order to determine if microbial sunscreen biosynthesis is a form of a strategy that cyanobacteria adopted to mitigate the harmful effects of UV radiation before formation of the ozone layer, time machine would be a great option if Stephen Hawking can manufacture one, but that is not feasible for the time being. This study will aim to find out whether microbial sunscreen production like scytonemin is one of the mitigation strategies adopted by microbes in the past through the study of microbial mats and cyanobacteria like Lyngbya aestuarii from Shark Bay, Western Australia. As we know, microbial mats from Shark bay, Western Australia are the analogues of ancient microbial mats and stromatolites, so the study of these modern mats may inform us how microbes in the ancient stromatolites/ microbial mats might have protected themselves from the harmful UV radiation in the past.

Using the above assumptions on manufacture of UV radiation shielding compounds, I plan to pursue my Honors study at University of New South Wales by focusing my studies on explaining how cyanobacteria protected itself from lethal UV radiation in the past; the study will focus more on the microbial sunscreen biosynthesis. Analysis of microbial sunscreen production from the microbial mats of Shark Bay would be of paramount importance, as it will help in explaining how the first living organisms on earth became resistant to the harmful UV radiation before the formation of ozone layer. This study may also be important in finding whether life could be present in other planets that do not have a protective layer from UV radiation. I will be honored to work under the supervision of Professor Brett Neilan and Dr. Brendan Burns from the Australian Centre for Astrobiology (ACA), since they are some of the leading researchers in cyanobacterial research, astrobiology and other areas of environmental microbiology. I have chosen to pursue my Honors study at University of New South Wales because of its reputation and scientific achievements, which will greatly help me build my career as a great researcher in cyanobacterial.

References

Codd, G. A., Morrison, L. F., & Metcalf, J. S. (2005). Cyanobacterial toxins: risk management for health protection. Toxicology and applied pharmacology, 203(3), 264-272.