3 research outputs found

    MOESM1 of Engineering a natural Saccharomyces cerevisiae strain for ethanol production from inulin by consolidated bioprocessing

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    Additional file 1: Table S1. The content of hexose in inulin and Jerusalem artichoke tuber powder (JAP). Fig. S1. Cell morphology and sporulation observed by optical microscopy. Fig. S2. Data on ethanol fermentation from inulin. Fig. S3. Codon-optimized sequences of the endo-inulinase gene in Penicillium sp. TN-88. Fig. S4. DNA cassettes used for transformation of S. cerevisia

    Table_1_Naphthylacetic Acid and Tea Polyphenol Application Promote Biomass and Lipid Production of Nervonic Acid-Producing Microalgae.docx

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    <p>Mychonastes afer HSO-3-1 is a potential producer of nervonic acid, which could be accumulated to 2–3% of dry cell weight. Improving the productivity of nervonic acid is critical to promote the commercialization of this product. In this study, 1-naphthylacetic acid (NAA) and tea polyphenol (TP) were selected as bioactive additives to stimulate the growth of M. afer. Supplementing NAA in the early growth stage and TP in the middle and late growth stage led to improved lipid accumulation in M. afer. The cultures supplemented with TP at the late growth stage maintained higher photosynthetic efficiency than the control groups without TP. Furthermore, the intracellular reactive oxygen species (ROS) accumulations in M. afer supplemented with 500 mg/L of TP was 63% lower than the control group. A linear relationship (R<sup>2</sup>= 0.899) between the values of Fv/Fm and ROS accumulation was established. We hypothesize supplement of bioactive additives at different growth stage could promote the cell growth rate and nervonic acid productivity of M. afer by retrieving intracellular ROS level. Further analysis of photosynthetic system II (PSII) protein in M. afer cultured in presence of NAA and TP indicated the levels of D1 and D2 proteins, the core skeleton proteins of PSII, showed 33.3 and 25.6% higher than the control group. CP43 protein, a critical module in PSII repair cycle, decreased significantly. These implied that TP possesses the function of slowing down the damage of PSII by scavenging excess intracellular ROS.</p

    Processive Degradation of Crystalline Cellulose by a Multimodular Endoglucanase via a Wirewalking Mode

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    Processive hydrolysis of crystalline cellulose by cellulases is a critical step for lignocellulose deconstruction. The classic Trichoderma reesei exoglucanase <i>Tr</i>Cel7A, which has a closed active-site tunnel, starts each processive run by threading the tunnel with a cellulose chain. Loop regions are necessary for tunnel conformation, resulting in weak thermostability of fungal exoglucanases. However, endoglucanase <i>Cc</i>Cel9A, from the thermophilic bacterium Clostridium cellulosi, comprises a glycoside hydrolase (GH) family 9 module with an open cleft and five carbohydrate-binding modules (CBMs) and hydrolyzes crystalline cellulose processively. How <i>Cc</i>Cel9A and other similar GH9 enzymes bind to the smooth surface of crystalline cellulose to achieve processivity is still unknown. Our results demonstrate that the C-terminal CBM3b and three CBMX2s enhance productive adsorption to cellulose, while the CBM3c adjacent to the GH9 is tightly bound to 11 glucosyl units, thereby extending the catalytic cleft to 17 subsites, which facilitates decrystallization by forming a supramodular binding surface. In the open cleft, the strong interaction forces between substrate-binding subsites and glucosyl rings enable cleavage of the hydrogen bonds and extraction of a single cellulose chain. In addition, subsite −4 is capable of drawing the chain to its favored location. Cellotetraose is released from the open cleft as the initial product to achieve high processivity, which is further hydrolyzed to cellotriose, cellobiose and glucose by the catalytic cleft of the endoglucanase. On this basis, we propose a wirewalking mode for processive degradation of crystalline cellulose by an endoglucanase, which provides insights for rational design of industrial cellulases
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