Strategic Growth Area: Economical and Sustainable Materials (ESM)

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Browsing Strategic Growth Area: Economical and Sustainable Materials (ESM) by Department "Biological Systems Engineering"

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    Coenzyme Engineering of a Hyperthermophilic 6-Phosphogluconate Dehydrogenase from NADP(+) to NAD(+) with Its Application to Biobatteries
    Chen, Hui; Zhu, Zhiguang; Huang, Rui; Zhang, Y. H. Percival (Nature Publishing Group, 2016-11-02)
    Engineering the coenzyme specificity of redox enzymes plays an important role in metabolic engineering, synthetic biology, and biocatalysis, but it has rarely been applied to bioelectrochemistry. Here we develop a rational design strategy to change the coenzyme specificity of 6-phosphogluconate dehydrogenase (6PGDH) from a hyperthermophilic bacterium Thermotoga maritima from its natural coenzyme NADP(+) to NAD(+). Through amino acid-sequence alignment of NADP(+)-and NAD(+)-preferred 6PGDH enzymes and computer-aided substrate-coenzyme docking, the key amino acid residues responsible for binding the phosphate group of NADP(+) were identified. Four mutants were obtained via site-directed mutagenesis. The best mutant N32E/R33I/T34I exhibited a x 6.4 x 10(4)-fold reversal of the coenzyme selectivity from NADP(+) to NAD(+). The maximum power density and current density of the biobattery catalyzed by the mutant were 0.135 mW cm(-2) and 0.255 mA cm(-2), similar to 25% higher than those obtained from the wide-type 6PGDH-based biobattery at the room temperature. By using this 6PGDH mutant, the optimal temperature of running the biobattery was as high as 65 degrees C, leading to a high power density of 1.75 mW cm(-2). This study demonstrates coenzyme engineering of a hyperthermophilic 6PGDH and its application to high-temperature biobatteries.
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    In-Field Performance of Biomass Balers
    Grisso, Robert D.; Webb, Erin G.; Cundiff, John S. (MDPI, 2020-12-04)
    Herbaceous biomass will contribute significantly to meeting renewable energy goals. Harvesting equipment for hay is generally suitable for mowing, raking, and baling grasses such as switchgrass; however, there is a need for field data to better understand machine performance in energy crops. The purpose of this study was to collect field data to estimate baler field capacity, throughput, and speed. Data gathered with a Differential Global Positioning System (DGPS) unit during baling provided time-motion studies of baler productivity. Six fields were used to compare field capacity, speed, and throughput results from four round balers and one large-square baler. The results show that in-field performance of round balers is significantly affected by yield, but that the relationship can be represented with machinery management concepts, knowledge of maximum throughput, and wrap-eject time. Baler performance will be overestimated if the yield, maximum throughput, and wrap-eject time are not correctly accounted for.
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    Overcoming Biomass Recalcitrance by Combining Genetically Modified Switchgrass and Cellulose Solvent-Based Lignocellulose Pretreatment
    Sathitsuksanoh, Noppadon; Xu, Bin; Zhao, Bingyu Y.; Zhang, Y. H. Percival (2013-09-27)
    Decreasing lignin content of plant biomass by genetic engineering is believed to mitigate biomass recalcitrance and improve saccharification efficiency of plant biomass. In this study, we compared two different pretreatment methods (i.e., dilute acid and cellulose solvent) on transgenic plant biomass samples having different lignin contents and investigated biomass saccharification efficiency. Without pretreatment, no correlation was observed between lignin contents of plant biomass and saccharification efficiency. After dilute acid pretreatment, a strong negative correlation between lignin content of plant samples and overall glucose release was observed, wherein the highest overall enzymatic glucan digestibility was 70% for the low-lignin sample. After cellulose solvent- and organic solvent-based lignocellulose fractionation pretreatment, there was no strong correlation between lignin contents and high saccharification efficiencies obtained (i.e., 80-90%). These results suggest that the importance of decreasing lignin content in plant biomass to saccharification was largely dependent on pretreatment choice and conditions.