In Ga As is an important bandgap-variable ternary semiconductor which has wide applications in electronics and optoelectronics. In this work, single-crystal In Ga As nanowires were synthesized by a chemical vapor depo...In Ga As is an important bandgap-variable ternary semiconductor which has wide applications in electronics and optoelectronics. In this work, single-crystal In Ga As nanowires were synthesized by a chemical vapor deposition method.Photoluminescence measurements indicate the In Ga As nanowires have strong light emission in near-infrared region. For the first time, photodetector based on as-grown In Ga As nanowires was also constructed. It shows good light response over a broad spectral range in infrared region with responsivity of 6.5×10~3 AW^(-1) and external quantum efficiency of 5.04×10~5%. This photodetector may have potential applications in integrated optoelectronic devices and systems.展开更多
Corynebacterium glutamicum represents an emerging recombinant protein expression factory due to its ideal features for protein secretion,but its applicability is harmed by the lack of an autoinduction system with tigh...Corynebacterium glutamicum represents an emerging recombinant protein expression factory due to its ideal features for protein secretion,but its applicability is harmed by the lack of an autoinduction system with tight regulation and high yield.Here,we propose a new recombinant protein manufacturing platform that leverages ethanol as both a delayed carbon source and an inducer.First,we reanalysed the native inducible promoter PICL from the acetate uptake operon and found that its limited capacity is the result of the inadequate translation initial architecture.The two strategies of bicistronic design and ribozyme-based insulator can ensure the high activity of this promoter.Next,through transcriptional engineering that alters transcription factor binding sites(TFBSs)and the first transcribed sequence,the truncated promoter PA256 with a dramatically higher transcription level was generated.When producing the superfolder green fluorescent protein(sfGFP)under 1%ethanol conditions,PA256 exhibited substantially lower protein accumulation in prophase but an approximately 2.5-fold greater final yield than the strong promoter PH36.This superior expression mode was further validated using two secreted proteins,camelid antibody fragment(VHH)and endoxylanase(XynA).Furthermore,utilizing CRISPRi technology,ethanol utilization blocking strains were created,and PA256 was shown to be impaired in the phosphotransacetylase(PTA)knockdown strains,indicating that ethanol metabolism into the tricarboxylic acid cycle is required for PA256 upregulation.Finally,this platform was applied to produce the“de novo design”protein NEO-2/15,and by introducing the N-propeptide of CspB,NEO-2/15 was effectively secreted with the accumulation 281 mg/L obtained after 24 h of shake-flask fermentation.To the best of our knowledge,this is the first report of NEO-2/15 secretory overexpression.展开更多
基金the NSF of China(Nos.61574054,61505051,11374092,11204073,61474040,and51302077)the National Basic Research Program of China(No.2012CB932703)+2 种基金the Hunan province science and technology plan(No.2014FJ2001,2014GK3015,and 2014TT1004)the Hunan Provincial Natural Science Foundation of China(No.2015JJ3049)the Aid program for Science and Technology Innovative Research Team in Higher Educational Institutions of Hunan Province
文摘In Ga As is an important bandgap-variable ternary semiconductor which has wide applications in electronics and optoelectronics. In this work, single-crystal In Ga As nanowires were synthesized by a chemical vapor deposition method.Photoluminescence measurements indicate the In Ga As nanowires have strong light emission in near-infrared region. For the first time, photodetector based on as-grown In Ga As nanowires was also constructed. It shows good light response over a broad spectral range in infrared region with responsivity of 6.5×10~3 AW^(-1) and external quantum efficiency of 5.04×10~5%. This photodetector may have potential applications in integrated optoelectronic devices and systems.
基金This work received funding from the National Natural Science Foundation of China(No.21878124,22078128,and 21938004)the Fundamental Research Funds for the Central Universities(No.JUSRP221032)+1 种基金the 111 Project(No.111-2-06)the national first-class discipline program of Light Industry Technology and Engineering(LITE2018-24).
文摘Corynebacterium glutamicum represents an emerging recombinant protein expression factory due to its ideal features for protein secretion,but its applicability is harmed by the lack of an autoinduction system with tight regulation and high yield.Here,we propose a new recombinant protein manufacturing platform that leverages ethanol as both a delayed carbon source and an inducer.First,we reanalysed the native inducible promoter PICL from the acetate uptake operon and found that its limited capacity is the result of the inadequate translation initial architecture.The two strategies of bicistronic design and ribozyme-based insulator can ensure the high activity of this promoter.Next,through transcriptional engineering that alters transcription factor binding sites(TFBSs)and the first transcribed sequence,the truncated promoter PA256 with a dramatically higher transcription level was generated.When producing the superfolder green fluorescent protein(sfGFP)under 1%ethanol conditions,PA256 exhibited substantially lower protein accumulation in prophase but an approximately 2.5-fold greater final yield than the strong promoter PH36.This superior expression mode was further validated using two secreted proteins,camelid antibody fragment(VHH)and endoxylanase(XynA).Furthermore,utilizing CRISPRi technology,ethanol utilization blocking strains were created,and PA256 was shown to be impaired in the phosphotransacetylase(PTA)knockdown strains,indicating that ethanol metabolism into the tricarboxylic acid cycle is required for PA256 upregulation.Finally,this platform was applied to produce the“de novo design”protein NEO-2/15,and by introducing the N-propeptide of CspB,NEO-2/15 was effectively secreted with the accumulation 281 mg/L obtained after 24 h of shake-flask fermentation.To the best of our knowledge,this is the first report of NEO-2/15 secretory overexpression.
