| 1 | Reservoir Characteristics and Preservation Conditions of Longmaxi Shale in the Upper Yangtze Block, South China显示文摘The Upper Ordovician-Lower Silurian Longmaxi Shale in the Upper Yangtze block represents one of the most important shale gas plays in China. The shale composition,porosity,organic thermal maturity,and methane sorption were investigated at the Qilongcun section in the Dingshan area,southeastern Sichuan Basin. The results show that the Upper Ordovician-Lower Silurian Longmaxi Shale contains:(1) sapropelic I organic matter;(2) a 40-m thick bedded sequence where total organic carbon(TOC) content is > 2%;(3) a 30-m thick layer at the base of the Longmaxi Shale with a brittle mineral content higher than 50%; and(4) a mean methane adsorption capacity of 1.80 cm^3/g(7 MPa pressure). A positive correlation between TOC and sorbed gas indicates that organic matter content exerts an important control on methane storage capacity. Based on the analysis of the shale reservoir characteristics,the lower member of the Longmaxi Shale can thus be considered a favorable stratum for shale gas exploration and exploitation. It has similar reservoir characteristics with the Longmaxi Shale in the Jiaoshiba area tested with a high-yield industrial gas flow. However,based on tectonic analysis,differences in the level of industrial gas flow between the low-yield study area and the high-yield Jiaoshiba area may result from different tectonic preservation conditions. Evidence from these studies indicates the shale gas potential of the Longmaxi Shale is constrained by the reservoir and preservation conditions. | RAN Bo LIU Shugen Luba JANSA SUN Wei YANG Di WANG Shiyu YE Yuehao Christopher XIAO ZHANHG Jian ZHAI Cangbo LUO Chao ZHANG Changjun | 2016 | Acta Geologica Sinica(English Edition)2016，90，6： | 6 |
| 3 | Combinatorial metabolic engineering of Saccharomyces cerevisiae for improved production of 7-dehydrocholesterol显示文摘7-Dehydrocholesterol(7-DHC),a key pharmaceutical intermediate in the production of vitamin D3,has a wide range of applications.To explore fermentative synthesis of 7-DHC,a 7-DHC-producing Saccharomyces cerevisiae strain was constructed by blocking the competitive pathway,eliminating rate-limiting steps,altering global reg-ulation,and pathway compartmentalization.After blocking the competitive pathway by disrupting ERG5 and ERG6 and introducing DHCR24 from Gallus gallus,S.cerevisiae produced 139.72 mg/L(17.04 mg/g dry cell weight,hereafter abbreviated as DCW)7-DHC.Subsequent alteration of global regulation by deleting ROX1 and overexpressing UPC2-1 increased 7-DHC production to 217.68 mg/L(37.56 mg/g DCW).To remove the accu-mulated squalene,the post-squalene pathway was strengthened by co-overexpression of PGAL1-driven ERG11 and PGAL10-driven ERG1,which improved 7-DHC titer and yield to 281.73 mg/L and 46.78 mg/g DCW,respectively,and reduced squalene content by 90.12%.We surmised that the sterol precursors in the plasma membrane and peroxisomes may not be accessible to the pathway enzymes,thus we re-localized DHCR24p and Erg2p-GGGGS-Erg3p to the plasma membrane and peroxisomes,boosting 7-DHC production to 357.53 mg/L(63.12 mg/g DCW).Iron supplementation further increased 7-DHC production to 370.68 mg/L in shake flasks and 1.56 g/L in fed-batch fermentation.This study demonstrates the power of global regulation and subcellular relocalization of key enzymes to improve 7-DHC synthesis in yeast. | Yuehao Gu Shuhui Chen Xue Jiao Qi Bian Lidan Ye Hongwei Yu | 2023 | Engineering Microbiology2023，3，4： | 0 |
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