My research

I study life and the world around it; how life interacts with and is shaped by and in turn impacts its environment. I think about this in the context of our modern Earth, back in time throughout Earth history, and forward, as ecosystems respond to climate change. And sometimes, other worlds beyond the Earth.

My early scientific interests explored the limits of life—the microbes that thrive in extreme environments; how viruses hijack machinery from their hosts to reproduce; how life beyond the Earth might be completely different from what we know here; how life may have first originated. My PhD focused on the Cyanobacteria—the first organisms to perform oxygenic photosynthesis ~2.4 billion years ago, releasing the first oxygen into the atmosphere and transforming the face of our planet forever. My current research remains centered on photosynthetic organisms, but has expanded from Cyanobacteria to eukaryotic algae. I aim to bridge our understanding of biology from the reductionist study of model organisms in the laboratory with a more holistic view of life in the context of ecosystems and geological processes. By integrating these different ways of knowing, I hope to help us better understand our biosphere and how we can protect it going forward.

I use culture-based and cell-free techniques to experimentally investigate microbial physiologies; bioinformatic tools to explore microbial communities; analytical and imaging techniques to examine chemistries and textures in both petrographic and biological samples; and I do both geological and ecological fieldwork.


postdoc projects

coming soon

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PhD projects


the origins of photosynthesis

The onset of oxygenic photosynthesis was a huge turning point in the history of life on Earth, and the element manganese played a key role in how and why oxygenic photosynthesis evolved when it did. To understand the processes and mechanisms involved, I deciphered the vestiges of ancient manganese cycling recorded in sedimentary rocks, and also examined physiologies involving manganese in modern Cyanobacteria.

Lingappa et al, 2019. “How manganese empowered life with dioxygen (and vice versa).”

feature on NASA astrobiology portal

Other papers hopefully coming soon! Until then, check out my PhD thesis defense seminar.

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ROCK VARNISH

Rock varnish is a dark rock coating found in arid environments. It contains extremely high manganese content, the basis of which was a long-standing mystery. My work on manganese and Cyanobacteria led me to an explanation: keystone members of the varnish ecosystem are Cyanobacteria that accumulate massive amounts of manganese in their cells as an antioxidant system. This adaptation enables their survival in the harsh environments where varnish develops and also provides a mechanism for the selective enrichment of manganese in varnish itself—encapsulating the complex interplay of environment shaping life and life shaping environment.

Lingappa et al, 2021. “An ecophysiological explanation for manganese enrichment in rock varnish.”


MICROBIAL MATS

Little Ambergris Cay, a tiny uninhabited island in the Turks and Caicos, hosts an amazing tidal lagoon full of microbial mats which resemble the microbial ecosystems that dominated the ancient biosphere before the evolution of plants and animals. I spearheaded a study on the microbes within these mat communities, and was also involved in studies on the island’s geochemistry and sedimentology. In 2017, Little Ambergris Cay was directly hit by the eyewall of Category 5 Hurricane Irma. Our subsequent work focused on documenting the impact and recovery from this devastating storm event.

mats6.JPG

Lingappa et al, 2022. “Early impacts of climate change on a coastal marine microbial mat ecosystem.”

Present et al, 2021. “Non-lithifying microbial ecosystem dissolves peritidal lime sand.”

Ward et al, 2020. “Microbial mats in the Turks and Caicos Islands reveal diversity and evolution of phototrophy in the Chloroflexota order Aggregatilineales.”

Gomes et al, 2020. “Taphonomy of biosignatures in microbial mats on Little Ambergris Cay, Turks and Caicos Islands.”

Trower et al, 2018. “Active ooid growth driven by sediment transport in a high energy shoal, Little Ambergris Cay, Turks and Caicos Islands.”


BORING CYANOBACTERIA

With Lizzy Trower, I studied the Cyanobacteria that bore into ooid sand grains to better understand the geological record of endolithic microbes and also biological CaCO3 dissolution processes with implications for how the oceans are responding to increasing atmospheric CO2 and acidification.

Lingappa et al. 2019 AGU poster. “Ecophysiology of ooid microborings excavated by endolithic Cyanobacteria.”

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OTHER PROJECTS

Yu et al, 2022 “Comparative studies on cultivated and uncultivated, freshwater and marine “Ca. Manganitrophaceae” genomes implicates their worldwide reach in manganese chemolithoautotrophy.”

Kim et al, 2022 “Challenges of measuring soluble Mn(III) species in natural samples.”

Douglas et al, 2021. “Impact of river channel lateral migration on microbial communities across a discontinuous permafrost floodplain.”

Liu et al, 2021. “Manganese oxides in Martian meteorites Northwest Africa (NWA) 7034 and 7533.”

Smith et al, 2020. “Physical controls on carbonate intraclasts: Modern flat pebbles from Great Salt Lake, Utah.”

Trower et al, 2018. “Microabrasive compositions containing ooids.”

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pre PhD projects


Viral capsid assembly

At Prosetta Biosciences, I helped develop a cell-free protein synthesis system for the translation and assembly of rabies viral capsid proteins. Using this system, I elucidated a pathway of capsid formation and established a screen for novel antiviral drugs that interfered with this pathway. I worked on rabies drug development for several small molecules that came out of this screen, and I characterized host multiprotein complexes and protein-protein interactions involved in rhabdovirus capsid assembly.

Lingappa et al, 2013. “Host-rabies virus protein-protein interactions as druggable antiviral targets.”

feature in Cell Leading Edge


ALGAE AND OUTER SPACE

At NASA Ames Research Center, I studied oxidative stress responses in the green algae Chlamydomonas reinhardtii and Volvox carteri—two organisms which represent the bookends of a model lineage for the evolution of multicellularity. Some of this work had applications for space biology, so I was also involved in biocompatibility for the development of biological payloads to fly in Earth orbit.


MARS ANALOG MICROBES1b2.1e

My undergraduate research at Hampshire College involved studying the microbes in rock varnish from the Mojave and Atacama deserts, specifically looking at UV resistant isolates as an analog for hypothetical microorganisms in rock coatings on Mars. I also brought this work to the Mars Desert Research Station as part of a simulated mission to Mars.


DYNAMICS OF A STAR CLUSTER

As a research assistant at the Cerro Tololo Inter-American Observatory, I studied the globular cluster NGC2808. I measured the radial velocity dispersion of the cluster, and split the populations of stars by elemental anticorrelations looking for different spatial distributions and/or kinematics.

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HST image of NGC2808