Comparative Analysis of Trifluoracetic Acid Pretreatment for Lignocellulosic Materials.

Lignocellulosic materials are usually processed toward C5 and C6 corresponding sugars. Trifluoroacetic acid (TFA) is a pretreatment method to solubilize hemicellulose to sugars such xylose without degrading cellulose. However, this pretreatment has not been compared to other processes. Thus, this paper focuses on the techno-economic comparison of the C5-C6 production of C5-C6 as raw materials platforms using non-centrifuged sugarcane bagasse (NCSB) and Pinus patula wood chips (PP). Hydrolysates using TFA 2.5 M as an acid were characterized through HPLC regarding arabinose, galactose glucose, xylose, and mannose sugars. Then, simulations of the processes according to the experimental results were done. The economic assessment was performed, and compared with some common pretreatments. The mass and energy balances of the simulations indicate that the process can be compared with other pretreatments. From the economic perspective, the main operating expenditures (OpEx) are related to raw materials and capital depreciation due to the cost of TFA corrosion issues. The processes showed a CapEx and OpEx of 0.99 MUSD and 6.59 M-USD/year for NCSB, and 0.97 MUSD and 4.37 MUSD/year for PP, considering a small-scale base (1 ton/h). TFA pretreatment is innovative and promising from a techno-economic perspective.

Design and development of a "Y-shaped" microbial consortium capable of simultaneously utilizing biomass sugars for efficient production of butanol.

Microbial production of chemicals from lignocellulosic biomass is usually hampered by the low efficiency of the simultaneous utilization of C5 and C6 sugars. In nature, this is not a problem because different C5- and C6-utilizing microorganisms cooperate. Nevertheless, the diverse metabolism of microorganisms in nature makes it difficult to synchronize the utilization of biomass sugars toward a specific goal. To address this problem, we sought to develop a novel microbial consortium that can mimic nature's ability of efficiently use biomass sugars, while synchronizing this capability toward a useful goal to maximize the power of nature and engineering. Starting from a completely chromosomally engineered butanol hyper-producing Escherichia coli strain that we developed previously, we developed a consortium comprising two E. coli strains with nearly identical genomic backgrounds, thus creating a "Y-shaped" consortium with two different "heads" (using xylose or glucose) but the same "body" (from glycolysis to butanol production). This "Y-shaped" chimeric consortium achieved the most efficient butanol production from mixed sugars reported to date, by equally efficient and orthogonal consumption of C5 and C6 sugars. Furthermore, we show that the consortium structure is not only adaptive to environmental perturbations, but can be arbitrarily changed to simultaneously utilize C5/C6 sugars in different ratio. The design and development of such a "Y-shaped" chimeric consortium provides a novel approach to address the need for simultaneous efficient utilization of different biomass sugars for the production of useful chemicals.