Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences
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Unusual acylation of chloramphenicol in Lysobacter enzymogenes , a biocontrol agent with intrinsic resistance to multiple antibiotics
No full textBackground: The environmental gliding bacteria Lysobacter are emerging as a new group of bio control agents dueto their prolific production of lytic enzymes and potent antibiotic natural products. These bacteria are intrinsicallyresistant to many antibioti cs, but the mechanisms behind the antibiotic resistance have not been investigated.
Results: Previously, we have used chloramphenicol acetyl transferase gene (ca t ) as a selection marker in genetic manipulation of natural product biosynthetic genes in Lysobac ter , because chloram phenicol is one of the two common antibiotics that Lysobacter are susceptible to. Here, we found L. enzymogenes, the most studied species of this genus, could still grow in th e p resen c e of a lo w c on centratio n of chlo ramphen icol . Th ree c hl oramphe nicol
derivatives (1–3) with an unusual acylation pattern were identified in a cat-containing mutant of L. enzymogenes and in the wild type. The compounds included chloramphenicol 3'-isobutyrate (1), a new compound chloramphenicol 1'-isobutyrate (2), and a rare chloramphenicol 3'-isovalerate (3). Furthermore, a mutation of a global regulator gene (clp) or a Gcn5-related N acetyltransferase (GNAT) gene in L. enzymogenes led to nearly no growth in media containing chloramphenicol, whereas a complementation of clp restored the chloramphenicol acylation as well as antibiotic HSAFproduction in the clp mutant.
Conclusions: The results indicated that L. enzymogenes contains a pool of unusual acyl donors for enzymatic modification of chloramphenicol that confers the resistance, which may involve the Clp-GNAT regulatory system.Because Lysobacter are ubiquitous inhabitants of soil and water, the finding may have important implications in understanding microbial competitions and bioactive natural product regulation
Ammonium, Nitrate, and Urea Play Different Roles for Lipid Accumulation in the Nervonic Acid - Producing Microalgae Mychonastes afer HSO-3-1.
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Preparation of 3D Architecture Graphdiyne Nanosheets for High-Performance Sodium-Ion Batteries and Capacitors
No full textHere, we apply three-dimensional (3D) architecture graphdiyne nanosheet (GDY-NS) as anode materials for sodium-ion storage devices achieving high energy and power performance along with excellent cyclic ability. The contribution of 3D architecture nanostructure and intramolecular pores of the GDY-NS can substantially optimize the sodium storage behavior through the accommodated intramolecular pore, 3D interconnective porous structure, and increased activity sites to facilitate a fast sodium-ion diffusion channel. The contribution of butadiyne linkages and the formation of a stable solid electrolyte interface layer are directly confirmed through the in situ Raman measurement. The GDY-NS-based sodium-ion batteries exhibit a stable reversible capacity of approximately 812 mAh g(-1) at a current density of 0.05 A g(-1) they maintain more than 405 mAh g(-1) over 1000 cycles at a current density of 1 A g(-1). Furthermore, the sodium-ion capacitors could deliver a capacitance more than 200 F g(-1) over 3000 cycles at 1 A g(-1) and display an initial specific energy as high as 182.3 Wh kg(-1) at a power density of 300 W kg(-1) and maintain specific energy of 166 Wh kg(-1) even at a power density of 15 000 W kg(-1). The high energy and power density along with excellent cyclic performance based on the GDY-NS anode offers a great potential toward application on next-generation energy storage devices
Sustainable preparation and characterization of thermally stable and functional cellulose nanocrystals and nanofibrils via formic acid hydrolysis. 2017, 2(1), 10-15.
No full textIn this work, a sustainable method to prepare functional cellulose nanocrystals (CNCs) and cellulose nanofibrils (CNFs) using formic acid (FA) (a recoverable organic acid) was established. After FA hydrolysis, the obtained CNCs could be well dispersed in DMAC. Thus, the CNC products and fibrous cellulosic solid residue (FCSR) in DMAC could be easily separated by a conventional centrifugal process, and the collected FCSR could be further fibrillated to CNFs with relatively low-intensity mechanical fibrillation process. The isolated CNC products showed high crystallinity index (about 75%) and excellent thermal stability (with onset thermal degradation temperature of 325 ºC). Both the resultant CNCs and CNFs showed better dispersibility in DMSO, DMF and DMAC respectively because of the introduction of ester groups on the surface of the products. The presence of surface ester groups could increase the interface compatibility of nanocelluloses with polymeric matrices and enable their application in reinforcing polymeric matrix materials (e.g. the composite films like PHVB+CNFs)
Recent progress on the pretreatment and fractionation of lignocelluloses for Biorefinery at QIBEBT.
No full textPretreatment or fractionation is one of the key steps for the conversion of lignocelluloses to sustainable biofuels, biomaterials or biochemicals, because pretreatment/fractionation can break the natural recalcitrance of lignocelluloses, improving the conversion efficiency of downstream processes. This paper will review the recent progress on pretreatment and fractionation of lignocelluloses for biorefinery in Qingdao Institute of Bioenergy and Bioprocess Technology (QIBEBT). Main technologies introduced were alkaline twin-screw extrusion pretreatment, modified alkali pretreatment, hydrogen peroxide-assisted sodium carbonate pretreatment, fractionation with formic acid, as well as the two-step fractionation by hot water treatment coupling ammonium sulfite treatment. With the development of these technologies, a pilot scale platform of pretreatment and saccharification was established in the pilot plant of QIBEBT
Effective removal of salicylic and gallic acids from single component and impurity-containing systems using an isatin-modified adsorption resin.
No full textIn this study, an isatin-modified adsorption resin named HF-02, which effectively adsorbs and removes
salicylic acid (SA) and gallic acid (GA) from aqueous phase, was prepared and characterized. Its
adsorption capacity towards these two adsorbates was higher than for the commercial hypercrosslinked
resins H103 and CHA-111, and the macroporous resins HPD 500, Amberlite XAD-7 and XAD-
4. This is attributed to its superior porous structure and modified groups. The adsorption capacity of HF-
02 towards SA is higher than for GA and its uptake amounts for SA and GA calculated by Freundlich
isotherm were 350.7 mg g 1 and 160.8 mg g 1, respectively. The difference is mainly because the
utilization ratio of adsorption sites in resins is lower when adsorbing GA and the hydrophilicity of GA is
stronger than SA. The thermodynamic parameters in single component systems indicated that the two
adsorption processes are exothermic and physical in nature. Furthermore, the molecular structure, initial
concentration and temperature determine the uptake amounts and adsorption rate of HF-02. It is
noteworthy that 1% NaOH aqueous solution and absolute ethanol gave a more efficient desorption
effect in the dynamic experiment than 363 K pure water. The salt-promoting effect of NaCl, the
complex-forming effect of Ni(II) and the ionization-inhibiting effect of H+ would enhance the uptake
amounts of HF-02 in impurity-containing systems
水力旋流器溢流管结构对微细颗粒分离的影响
No full text针对直径为50 mm的小直径水力旋流器，考察了溢流管插入深度和壁厚以及进口流量对微细物料分离效率的影响，并利用正交分析法得到了溢流管最优的插入深度、壁厚及最适的进口流量。此外，考察了两种套筒式溢流管对水力旋流器分离性能的影响。最后，在最优溢流管结构的基础上，探讨了分流比对分离效率的影响。结果表明：水力旋流器的直筒段具有一定的分离作用；对于微细物料的分离，溢流管采用薄壁且插入深度与水力旋流器直筒段长度相当的设计，有利于提高微细颗粒的分离效率。小直径水力旋流器溢流管的最佳插入深度比例大于大直径水力旋流器的最佳插入深度比例，表明它们的分离行为存在着较大的差异。The separation efficiencies were compared under different vortex finder lengths, thickness and flow rates in a small hydrocyclone with the diameter of 50 mm, and the optimal insertion depth, wall thickness of the vortex finder and flow rate were obtained by using the method of orthogonal design. In addition, the influence of vortex finders with tube-in-tube structure in the hydrocyclone on the separation efficiency was investigated. Finally, the relationship between the split ratio and separation efficiency was analyzed on the basis of the optimal structure for the vortex finder. The experimental results show that the cylindrical part of the hydrocyclone plays an important preliminary separation role. For the separation of fine particles, a thin vortex finder which is extended to the junction between the cylindrical and the conical parts is beneficial to the separation efficiency. The optimum proportion of the vortex finder insertion depth to the hydrocyclone diameter in the small hydrocyclone is bigger than those in the big ones, and it is indicated that there is a remarkable difference of separation between them
Contribution of the Polarity of Mussel-Inspired Adhesives in the Realization of Strong Underwater Bonding
No full textAlthough the role of 3,4-dihydroxyphenyl-L-alanine(DOPA)in mussel foot proteins (mfps) in the realization of underwater bonding has been widely recognized, the role of the polarity of the polymer was largely overlooked. Here, by systematically comparing the underwater bonding properties of four mussel-inspired adhesives with different amide/lactam contents but similar catechol contents and molecular weights, we came to the conclusion that the polarity of the polymers also contributes to the strong underwater bonding. With the increase in the amide/lactam contents, the polarity of the polymeric adhesive increases, which correlates to the improved underwater bonding strength. A dielectric constant is introduced to evaluate the polarity of the polymer, which may be used as a guidance for the design of mussel-inspired adhesives with even better underwater bonding properties