Design and characterization of synthetic fungal-bacterial consortia for direct production of isobutanol from cellulosic biomass

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 110; no. 36; pp. 14592 - 14597
• Main Authors: Minty, Jeremy J., Singer, Marc E., Scholz, Scott A., Bae, Chang-Hoon, Ahn, Jung-Ho, Foster, Clifton E., Liao, James C., Lin, Xiaoxia Nina
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 03.09.2013; National Acad Sciences
• Subjects: Algorithms; bacteria; Bacteria - growth & development; Bacteria - metabolism; Biofuels; Biological Sciences; Biomass; Biomass production; bioprocessing; Biosynthesis; Biotechnology; Butanols - metabolism; Cell growth; Cellulase - metabolism; cellulases; Cellulose; Cellulose - metabolism; corn stover; E coli; Ecological engineering; Ecology; engineering; Enzymes; Escherichia coli; Escherichia coli - growth & development; Escherichia coli - metabolism; feedstocks; Fermentation; Fungal Proteins - metabolism; Fungi; Fungi - growth & development; Fungi - metabolism; Hydrolysis; Hypocrea jecorina; Industrial Microbiology - methods; Lignin - metabolism; lignocellulose; mathematical models; Microbial activity; microbial communities; Microbial Consortia; Modeling; Models, Biological; Oligosaccharides - metabolism; Physical Sciences; Population stability; Reproducibility of Results; Saccharides; Sensitivity analysis; Stover; Trichoderma - growth & development; Trichoderma - metabolism; Trichoderma reesei; renewable energy; consolidated bioprocessing; lignocellulosic biofuel
• ISSN: 0027-8424; 1091-6490; 1091-6490
• DOI: 10.1073/pnas.1218447110

Synergistic microbial communities are ubiquitous in nature and exhibit appealing features, such as sophisticated metabolic capabilities and robustness. This has inspired fast-growing interest in engineering synthetic microbial consortia for biotechnology development. However, there are relatively few reports of their use in real-world applications, and achieving population stability and regulation has proven to be challenging. In this work, we bridge ecology theory with engineering principles to develop robust synthetic fungal-bacterial consortia for efficient biosynthesis of valuable products from lignocellulosic feedstocks. The required biological functions are divided between two specialists: the fungus Trichoderma reesei , which secretes cellulase enzymes to hydrolyze lignocellulosic biomass into soluble saccharides, and the bacterium Escherichia coli , which metabolizes soluble saccharides into desired products. We developed and experimentally validated a comprehensive mathematical model for T. reesei / E. coli consortia, providing insights on key determinants of the system’s performance. To illustrate the bioprocessing potential of this consortium, we demonstrate direct conversion of microcrystalline cellulose and pretreated corn stover to isobutanol. Without costly nutrient supplementation, we achieved titers up to 1.88 g/L and yields up to 62% of theoretical maximum. In addition, we show that cooperator–cheater dynamics within T. reesei / E. coli consortia lead to stable population equilibria and provide a mechanism for tuning composition. Although we offer isobutanol production as a proof-of-concept application, our modular system could be readily adapted for production of many other valuable biochemicals.