Metabolic characterization of anaerobic fungi provides a path forward for bioprocessing of crude lignocellulose
Abstract
The conversion of lignocellulose‐rich biomass to bio‐based chemicals and higher order fuels remains a grand challenge, as single‐microbe approaches often cannot drive both deconstruction and chemical production steps. In contrast, consortia based bioprocessing leverages the strengths of different microbes to distribute metabolic loads and achieve process synergy, product diversity, and bolster yields. Here, we describe a biphasic fermentation scheme that combines the lignocellulolytic action of anaerobic fungi isolated from large herbivores with domesticated microbes for bioproduction. When grown in batch culture, anaerobic fungi release excess sugars from both cellulose and crude biomass due to a wealth of highly expressed carbohydrate active enzymes (CAZymes), converting as much as 49% of cellulose to free glucose. This sugar‐rich hydrolysate readily supports growth of Saccharomyces cerevisiae, which can be engineered to produce a range of value‐added chemicals. Further, construction of metabolic pathways from transcriptomic data reveals that anaerobic fungi do not catabolize all sugars that their enzymes hydrolyze from biomass, leaving other carbohydrates such as galactose, arabinose, and mannose available as nutritional links to other microbes in their consortium. Although basal expression of CAZymes in anaerobic fungi is high, it is drastically amplified by cellobiose breakout products encountered during biomass hydrolysis. Overall, these results suggest that anaerobic fungi provide a nutritional benefit to the rumen microbiome, which can be harnessed to design synthetic microbial communities that compartmentalize biomass degradation and bioproduct formation.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Jan 08, 2018
- Source ID
- 10.1002/bit.26515
Entities
People
- Chuck R. Smallwood
- James E Evans
- John K. Henske
- Kevin V. Solomon
- Michael K. Theodorou
- Michelle O'Malley
- St. Elmo Wilken
- Vaithiyalingam Shutthanandan
Organizations
- Division of Molecular & Cellular Biosciences
- Environmental Molecular Sciences Laboratory
- Harper Adams University
- Office of Biological and Environmental Research
- Purdue University
- United States Department of Energy
- University of California, Santa Barbara