Our model system, the passalid beetle Odontotaenius disjuctus, is a subsocial insect that process large amounts of woody biomass, surviving on a low-nutrient diet likely through a symbiotic relationships with gut microorganisms.
The passalid beetle gut is highly compartmentalized, providing unique microenvironments that favor the segregation of microbial populations and metabolic processes.
Understanding how these populations use nutrients and decompose lignocellulosic materials can help to optimize industrial biofuel production processes. To understand the complex symbiotic relationships in the passalid digestive system we are defining the environment where these microorganisms interact, and indentifying the location of key species and their functions using the following approaches:
- Microelectrodes and micromanipulators to characterize physiological gradients relevant to lignocellulose deconstruction and hydrogen generation, including pH, O2, H2, and Eh.
- Metagenomic and metatranscriptomic sequencing to determine the metabolic potential of discrete gut regions
- Functional metagenomic screening and sequencing (fosmid libraries) to identify oxidative and carbohydrate active enzymes
- Use of our newly developed Chip-SIP approach for high-throughput measurement of stable isotope incorporation into microorganisms using microarray hybridization and NanoSIMS spectroscopy.
- Fourier Transform Infrared Spectroscopy to monitor the transformation of plant polymers through the beetle gut (collaboration with Zhao Hao in the Holman group @ LBNL)
- 13C-TMAH Thermochemolysis to study the chemical modification of lignin (collaboration with Prof. Tim Filley, Purdue).
- Analysis of C and H stable isotopic fractionation to study methanogenesis (collaboration with Mark Conrad and Markus Bill at the Center for Isotope Biogeochemistry, LBNL)
This project is funded by the Department of Energy, Biological and Environmental Research, Genomic Science program and is a subaward of the Lawrence Livermore National Lab Biofuels SFA (Jennifer Pett-Ridge, Technical Lead)