Deep-sea hydrothermal vent bacterium Thiomicrospira crunogena can generate intracellular bicarbonate concentrations that are 100X higher than extracellular.  We’re determining the molecular mechanism of this process using genomic, molecular, and pharmacological approaches.

We are currently taking a bioinformatics-based approach to understand autotroph physiology.  Thus far, our efforts have focused on central carbon metabolism (the citric acid cycle has a few surprises up its sleeve for organisms that use it primarily for biosynthesis), as well as comparing predictions of energetic cost of using different carbon fixation pathways to build cells.

Mutually beneficial partnerships between autotrophic bacteria and marine invertebrates are common in areas with elevated levels of sulfide or other reductants (e.g., hydrothermal vents).  We study the biochemistry and physiology of these systems.

The amounts of 12-C and 13-C in biogenic materials are used to make inferences about factors influencing autotrophic organisms in ancient and contemporary habitats.  RubisCO, the Calvin cycle carboxylase, fixes 13-CO2 more slowly than 12-CO2.  As a result, interpretation of the isotopic composition of biomass must include the impact of RubisCO isotope discrimination.  Unfortunately, it is commonly assumed that all RubisCOs fractionate carbon to the same degree.  Our experiments indicate otherwise — enzyme from marine algae discriminate less (far, far less in some cases).

Chemolithoautotrophs that act as CO2 vacuums

Carbon fixation by chemolithoautotrophic symbioses

Comparative genomics of autotrophic organisms

Isotope discrimination by RubisCO enzymes

Projects

All of the above  are made possible by funding from the following agencies, for which we are deeply grateful.

University of South Florida

We’ll fix *your* carbon...