From Life on Earth to Life Elsewhere - How Biology Shapes Our World

Algae can grow with amazing speed—as anyone who has ever maintained a swimming pool can tell you. This is thanks to algae’s ability to biochemically boost photosynthesis. One of the crucial steps of the photosynthetic process involves pulling carbon dioxide out of the air and then using it to construct carbon-based sugars inside a cellular factory. But funny enough, plants aren’t actually very efficient at doing this, despite the centrality of photosynthesis to their way of life. It turns out that photosynthesis is a victim of its own success. When it first evolved in bacteria about 3 billion years ago, the planet’s atmosphere had plenty of carbon dioxide. Now, however, our atmosphere is oxygen rich thanks to photosynthetic activity. And oxygen slows the gears of the photosynthetic apparatus.  Algae, however, have mechanisms for concentrating carbon dioxide in the cell, speeding up their production of sugars and other nutrients. Carnegie’s Adrien Burlacot has spent much of his career elucidating these capabilities in detail, with a particular focus on the bio-energetic mechanisms that make them possible. Harnessing algae’s special abilities could increase agricultural productivity, fight global hunger, and remove more carbon pollution from the atmosphere—contributing to climate change mitigation.

‘Omics’ is a relatively new research term that refers to a collective effort to identify, characterize, and quantify groups of biomolecules within a cell—or in a community—and to understand their contributions to the complex physiology of the organism—or to dynamic group interactions. It represents the intersection of a variety of specialties, including genomics, proteomics, metabolomics. In many ways, it leapfrogs over the classical methods of microbiology and takes a systems view of studying biology. Carnegie’s Devaki Bhaya is pursuing an ‘omics approach to understanding the microbial communities that are adapted to thrive in the extreme conditions of Yellowstone National Park’s hot springs. Her research has revealed the lateral transfer of genes between microbes, which is the bacterial version of loaning your neighbor a cup of sugar.  Looking ahead, she is keen to link her work on extremophiles with the origins of life research undertaken by astrobiologists and geomicrobiologists.

Earth is an active planet, which means that it’s difficult to trace chemical signals backward through time, particularly evidence of biochemical interactions. These molecules are irrevocably altered by geologic processes. As a result, paleobiologists who search for signs of Earth’s most ancient life have long relied on fossil organisms, including microscopic fossils of single cells, as well as the mineralized remains of cellular structures such as mound-like stromatolites, which provide convincing evidence of life as far back as 3.5 billion years ago. However, such remains are few and far between. Pairing cutting-edge chemistry with artificial intelligence, a multidisciplinary team of scientists led by Carnegie Earth & Planets Laboratory scientists Robert Hazen, Michael Wong, and Anirudh Prabhu recently found molecular evidence that oxygen-producing photosynthesis was at work at least 2.5 billion years ago. This finding extends the chemical record of photosynthesis preserved in carbon molecules by over 800 million years. The researchers concluded that information-rich attributes of ancient organic matter, even though highly degraded and with few if any surviving biomolecules, can still reveal much about the nature and evolution of life.