Current Members

Principal Investigator

photograph portrait of Victoria Orphan

Victoria Orphan

James Irvine Professor of Environmental Science and Geobiology


Graduate Students

photograph portrait of Grayson Chadwick

Grayson Chadwick

2010 - Present, Geobiology

I am interested in the mechanism of metabolic interaction between the two partner organisms in the AOM process. We recently found evidence supporting the hypothesis that electrons are directly shared between the two partners. I am investigating these ideas further by attempting to express and biochemically characterize the proteins that we think may be responsible. I am also interested in the better understanding the functional differences between ANME subgroups at higher phylogenetic resolution than has been previously been considered.

photograph portrait of Sean W Mullin

Sean W. Mullin

2013 - Present, Geobiology

My research interests are primarily focused around microbe-mineral interactions, especially as related to subsurface and deep biosphere communities. In particular, I focus on using micro-scale approaches to visualize the ways that microbes colonize various minerals as well as try to discern how the mineralogy affects the microbial assemblage in an area and the ways in which microbial metabolism can change the local mineralogy. We can do this using SEM, coupled Raman and deep-UV spectroscopy, as well as more familiar microbiological techniques like FISH microscopy and iTAG sequencing of 16S rRNA. I work with both in vitro and in situ communities, and the field sites I currently work in are a carbonate groundwater aquifer in Death Valley (~0.8 km deep) and the Subsurface Undgerground Research Facility in  South Dakota (~1.5 km deep). I am also dabbling in making my own glasses with controlled compositions and redox states to use as a defined substrate for more precise experiments.

photograph portrait of Kyle Metcalf

Kyle Metcalfe

2014 - Present, Geobiology

I am interested in using analysis of microbe-mineral interactions in modern sediments and experiments to provide insight into unresolved problems in Earth history. Working in the Orphan Lab, I am focusing on disentangling complex interactions between microbial communities and their clay mineral hosts in seafloor sediments to understand how these communities can shape their mineralogical environment, which may provide clues to tracing the imprint of life on the rock record here on Earth and beyond.

photograph portrait of Sujung Lim

Sujung Lim

2015 - Present, Geobiology

My research involves anaerobic environmental microbiology in the context of laboratory-tractable systems. More specifically, I study spatial organization in syntrophies. In these systems, I am attempting to determine the patterns of spatial arrangement in partnered microorganisms and the role the mechanism of their interactions play to drive these patterns. Ultimately, I would like to use this data - derived from lab-grown cultures - and apply it to more intractable systems, such as those cooperative microbial interactions found in the environment. I also have a project studying division of labor in the context of the anaerobic chitin degradation pathway in seafloor mud.

photograph portrait of Usha Lingappa

Usha Lingappa

2015 - Present, Geobiology

I'm interested in microbial metabolisms and the biogenesis of proteins that play important roles for biogeochemical processes in the environment. In the Orphan Lab, I'm developing a cell-free protein synthesis system to study enzymes that are central to archaeal methane metabolism. I'm also investigating the ecology and geobiology of microbial mats on Little Ambergris Cay.

photograph portrait of Cecilia Sanders

Cecilia Sanders

2016 - Present, Planetary Science

I am interested in the origins of life on rocky and icy worlds. How does the abiological (mineralogy, availability of water and pore space, availability of energy) inform the biological (microbial communities, metabolic staples) and vice versa? How do we study those connections in the rock record and modern extreme habitats?

photograph portrait of Aditi Narayanan

Aditi Narayanan

2017 - Present, Biology

I'm interested in the impact of viruses on nutrient cycles and microbial ecology in marine habitats. I primarily use TEM and epifluroescence microscopy, sequencing, and nanoscale secondary ion mass spectrometry (nanoSIMS) to answer questions regarding viral activity and identity in the deep ocean.

photograph portrait of Yongzhao Guo

Yongzhao Guo

2018 - Present, Environmental Science and Engineering

I am interested in the growth and interactions within the slowly-growing syntrophic AOM consortia. My current research focuses on tracking the spatial growth patterns for AOM consortia using microcosms and imaging approaches. Combined with the meta-omics data, I am also focusing on the metabolic interactions by spatially targeting mRNA signals at molecular- and single-cell levels.


Postdoctoral Scholars

photograph portrait of Ranjani Murali

Ranjani Murali

2016 - Present, Biochemistry

I am interested in understanding the biochemical mechanisms that underlie microbial adaptation to unique environments. I use biochemical and biophysical assays to characterize proteins, particularly membrane proteins that are involved in novel electron transport chains. I am also interested in using fluorescence and electron microscopy techniques to look at samples with low microbial abundance.

photograph portrait of Haley Sapers

Haley Sapers

2016 - Present

My interdisciplinary research into the interactions between microorganisms and their abiotic substrates reflects my fascination with the biogeochemical interface. I grew up in Edmonton Alberta where cold (sub -40) winters precluded outdoor pursuits for a large part of year – instilling in me a love for the spring, sun, and ocean – I can never let a sunny day go by without poking around outside under rocks. I completed my PhD in Geology, Planetary Science at the Centre for Planetary Science and Exploration at Western University in London, Ontario Canada where I investigated the role impact cratering has on facilitating microbial colonization and the potential for microbial metabolism to be preserved as conspicuous geochemical patterns in the rock record. In the Orphan Lab I am part of the NASA Astrobiology Life Underground Team lead by Dr. Jan Amend at USC and a member of the SHERLOC team at JPL lead by Drs. Luther Beegle and Rohit Bhartia. In my role on all three teams I am involved in developing in situ flow through microbial colonization experiments at the Sandford Underground Research Facility to investigate microbial activity in the terrestrial subsurface by integrating microbial activity monitoring experiments with a pipeline at JPL to use deep UV Raman and fluorescence spectroscopy at integrated observational scales to identify and characterize microbial activity while retaining the spatial context of the colonization substrate. When I’m not in the lab I’m usually hiking, running, knitting, or playing the tuba.

photograph portrait of Daan Speth

Daan Speth

2016 - Present

I'm interested in the physiology of microorganisms that (obligately) interact with other community members. My research focuses on the interactions within microbial communities using spatial organization at the micron scale. Most of my PhD work was focused on genome-resolved metagenomic analysis of microbial communities of varying complexity. Many of the genomes obtained using this method show indications of interaction with community members. As genome-resolved metagenomics is maturing, the majority of sequenced genomes will soon be derived from uncultured organisms. Both genome interpretation and testing of hypotheses generated from 'omics data are challenging with the existing model systems. Using microbial cooccurence patterns, I intend to enrich naturally occurring consortia to study the molecular basis for their interaction and to diversify the available model systems.

photograph portrait of Fabai Wu

Fabai Wu

2016 - Present

I am a biophysicist and microbiologist. In the Orphan lab, I develop approaches to disentangle the various strategies which microbes established to budget their energy in response to environmental constraints.

photograph portrait of Hang Yu Hank

Hang Yu (Hank)

2017 - Present

I am interested in the cycling of carbon and sulfur in deep sea methane seeps. This process is accomplished by a microbial consortia but their symbiotic mechanism remains elusive. Combining microcosms and meta-omics, my research aims to illuminate how this deep biogeochemical cycling is accomplished by the collaborative power of the small.

photograph portrait of Antoine

Antoine Cremiere

2017 - Present

photograph portrait of Alon Philosof

Alon Philosof

2018 - Present

I am interested in the ecological role of viruses (mainly phages) in the marine environment. Globally, viruses constitute a large and abundant biomass, and are the second largest biomass in the oceans, exceeded only by the total biomass of bacteria. I am especially interested in understanding the temporal and spatial dynamics of host-virus interactions in the environment and the role of viruses as drivers of microbial growth, metabolism and microbial mortality. My research aims to supplement meta-omic methods with direct in situ measurements of viral production, viral activity and transfer of nutrients.

photograph portrait of Yamini

Yamini Jangir

2018 - Present

My research interest lies in developing and harnessing electrochemical techniques that enable enhanced characterization of the unexplored subsurface biosphere. During my doctoral research at the University of Southern California, I colonized continental subsurface microbes on electrodes biased at metabolically relevant potentials to act as a surrogate for naturally occurring minerals. I applied electrochemical approaches both in situ (Death Valley, CA) and ex situ (Sanford Underground Research Facility, SD; SURF) to mimic the complex interactions and energetic gradients present in these field sites. I extensively used genomics to reveal the diversity of subsurface microorganisms on each electrode, and isolated pure bacterial strains for further electrochemical analysis. Building on my past expertise in studying subsurface microbes on poised electrodes, my near-term plan at Orphan lab is to study the responses of syntrophic biofilm communities under varying simulated (redox) environments. I am also interested in understanding the energy distribution mechanism across the syntrophic biofilm on the electrode.


Staff Scientists

photograph portrait of Stephanie Connon

Stephanie Connon

2010 - Present

photograph portrait of John Magyar

John Magyar

2017 - Present