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关键词： Microfibers   Microplastics   Recycling   PET   CLY   Wood-based cellulose fibers   Biodegradation  

摘要： As global production of textiles rapidly grows, there is urgency to understand the persistence of fabrics in the marine environment, particularly from the microfibers they shed during wearing and washing. Here, we show that fabrics containing polyester (one of the most common plastics) remained relatively intact (viz., with a limited biofilm) after >200 days in seawater off the Scripps Oceanography pier (La Jolla, CA), in contrast to wood based cellulose fabrics that fell apart within 30 days. We also show similar results under experimental aquaria (in open circuit with the pier waters) as well as bioreactor settings (in close circuit, using microbial inoculum from the North Sea, off Belgium), using nonwoven fabrics and individual fibers, respectively. The fact that fibers released from synthetic textiles remain persistent and non-biodegradable despite their small (invisible) size, highlights concern for the growing industry that uses polyester from recycled plastics to make clothing. (C) 2021 The Authors. Published by Elsevier B.V.

关键词： Carbohydrates   Fluxes   Ethanol   Oxygen   Optimization  

摘要： The application of economic model predictive control (EMPC) techniques in bioprocesses is scarce due to limitations in obtaining accurate dynamic models. Simplified unstructured models (e.g., Monod) can be easily developed, but their prediction capacity is poor. On the other hand, models based on dynamic flux balance analysis (dFBA) of the detailed metabolic network appear as a promising alternative. However, using dFBA inside the controller leads to a bilevel optimization problem, which could require excessive computational effort. In the present work, a control approach is proposed to tackle this limitation. By combining mass balances with a surrogate model for the metabolic network, our approach provides a significant reduction in online computation while still accurately describing the microorganism of interest. A case study of a fed-batch bioreactor of Saccharomyces cerevisiae for ethanol maximization was chosen to test the new approach. First, flux balance analysis simulations with Yeast 8.30 genome-scale model were performed, then a simple polynomial model was fitted to these data by partial least-squares regression (PLSR). The identification step showed that only 11 PLS components were necessary to allow the FBA to be replaced by the surrogate model with a good accuracy. The surrogate model was coupled to the EMPC, and the results were similar to those presented in the literature, where the bilevel optimization problem is explicitly solved. The EMPC was able to compensate for structural errors in the identification process, and it provided a higher ethanol titer in comparison to the open-loop operation. The results showed that applying surrogate models to dFBA is a viable strategy to the solution of a bilevel optimization problem.

标准号: T/ZGM 004-2021

关键词： biological hydrogen production   dynamic membrane bioreactor   microbial community structure   Sporolactobacillus   substrate affinity  

摘要： The aim of this study was to evaluate the feasibility of biological hydrogen production (BHP) in a dynamic membrane bioreactor. Hydraulic retention time (HRT) was varied from 1 to 12 hours, and the microbial communities were analyzed. The major hydrogen-producing bacterium wasClostridium chromiireducens, which was enriched up to 82% of the total bacteria with a 2 hour HRT, whileEnterobacter cloacaewas also observed in the range of 0.2% to 34.4% of total bacteria. When the level of the substrate in the reactor was low (<0.5 g/L), BHP dropped dramatically, andSporolactobacillus putidusincreased to 8.8% of the total bacteria. Differences in substrate affinity betweenS. putidusandC. chromiireducenslikely promoted the dominance ofS. putidus, which is more favorable for growth and metabolism at low substrate concentrations, and caused changes in the microbial community.

关键词： outer membrane vesicles   hydratase   decarboxylase   biocatalysis   nano-scale bioreactor  

摘要： Bacterial outer membrane vesicles (OMVs) are small unilamellar proteoliposomes, involved in various functions including cell-to-cell signalling and protein excretion. We have engineered the OMVs of Escherichia coli to nano-scaled bioreactors for the biotransformation of fatty acids by targeting a fatty acid double bond hydratase of Stentrophomonas maltophilia (SmOhyA) and/or a photoactivated fatty acid decarboxylase from Chlorella variabilis NC64 A (CvFAP) into OMVs. Engineered OMVs containing both SmOhyA and CvFAP were able to catalyse the transformation of oleic acid ((Z)-octadec-9-enoic acid) into 9-hydroxyheptadecane via (R)-10-hydroxyoctadecanoic acid. The specific biotransformation rates of oleic acid reached 8.0x10(-12) mu mol/min per OMV.

关键词： Chitosan   n-hexane   Silicone oil   Two-phase partitioning bioreactor   Cell surface hydrophobicity  

摘要： Two-phase partitioning bioreactors (TPPBs) have been extensively used for volatile organic compounds (VOCs) removal. To date, most studies have focused on improving the mass transfer of gas phases/non-aqueous phases (NAPs)/aqueous phases, whereas the NAP/biological phases and gas/biological phases transfer has been neglected. Herein, chitosan was introduced into a TPPB to increase cell surface hydrophobicity (CSH) and improve the n-hexane mass transfer. The performance and stability of the TPPB with chitosan for n-hexane biodegradation were investigated, and it was found out that the TPPB with chitosan achieved maximum removal efficiency and elimination capacity of 80.6% and 26.5 g m- 3 h-1, thereby reaching much higher values than those obtained without chitosan (61.3% and 15.2 g m- 3 h-1). Chitosan not only obvio usly increased cell surface hydrophobicity and cell dry biomass on the surface of silicone oil, but might also allow hydrophobic cells in aqueous phases to directly capture and biodegrade n-hexane, resulting in an obvious improvement of mass transfer from the gas phase to biomass. Stability enhancement was another attractive advantage from chitosan addition. This study might provide a new strategy for the development of TPPB in the hydrophobic VOCs treatment.

关键词： Liquid-solid fluidization   Shear stress   Particles collisions   Computational fluid dynamics   Biofilm   Tapered bioreactors  

摘要： Fluidized beds in tapered geometries provide advantages such as a broad range of optimum operating ***,the dynamics of the flow inside these bioreactors is significantly more complex,as they promote non-uniform bioparticles *** this end,the CFD technique can give a detailed description of the flow in the ***,the aim of this work is to assess the influence of the hydrodynamic on the steady-state biofilm thickness through numerical simulations of liquid–solid fluidized *** geometries of tapered bioreactors in the operating conditions used to develop *** were run to solve the two-phase RANS equations using the open-source software OpenFOAM in *** SST k−ω model was used to estimate the turbulent features of the *** and bioparticles distribution inside the reactor were analyzed for different inlet velocities,while bioparticles collision frequency and shear stresses were evaluated for various operating *** comparison between the turbulent kinetic energy and the granular temperature indicated that the fluid flow is more turbulent than the bioparticles *** hydrodynamics influence on the steady-state biofilm thickness was assessed,and results led to the conclusion that biofilm is more sensitive to hydrodynamic shear stress than bioparticles collisions.

关键词： 材料   支架材料   三维支架   聚氨酯   生物反应器   生物人工肝   生物相容性  

摘要： 背景:生物反应器是生物人工肝的核心部分,其性能直接关系到生物人工肝支持治疗的效果和作用。将支架材料应用于中空纤维性反应器中有望解决中空纤维型反应器对肝细胞培养支持不足的问题。目的:筛选可用于生物人工肝反应器构建的三维支架材料。方法:检测聚氨酯、壳聚糖、聚乳酸-聚羟乙酸酯支架材料的孔隙率。将HL-7702人肝细胞分别接种于3种支架上,培养4 h时,检测细胞接种率;培养24 h时,检测细胞活性与细胞内乳酸脱氢酶漏出量;培养3 d时,检测细胞内白蛋白合成量。根据上述实验结果选择聚氨酯进行以下实验:鼠尾胶原被覆组,以鼠尾胶原溶液浸泡材料后接种HL-7702人肝细胞悬液;纤维蛋白凝胶组,以含纤维蛋白原的培养液重悬HL-7702人肝细胞,随后接种于支架上;聚氨酯对照组,直接接种HL-7702人肝细胞悬液。培养1,3,5,7 d后,检测细胞活性、细胞内乳酸脱氢酶漏出量与白蛋白合成量。结果与结论:①3种支架均为多孔结构,聚氨酯和壳聚糖有较好的弹性,聚乳酸-聚羟乙酸酯质地较硬,聚氨酯和壳聚糖支架材料的孔隙率显著高于聚乳酸-聚羟乙酸酯(P<0.05);②聚氨酯内的细胞接种率高于聚乳酸-聚羟乙酸酯(P<0.05),低于壳聚糖(P<0.05);聚氨酯、壳聚糖内的细胞活性与白蛋白合成量高于聚乳酸-聚羟乙酸酯(P<0.05);3组间的细胞内乳酸脱氢酶漏出量比较差异无显著性意义(P>0.05);③纤维蛋白凝胶组的细胞分布较聚氨酯对照组、鼠尾胶原被覆组均匀,培养3,5,7 d的细胞活性与白蛋白含量高于聚氨酯对照组、鼠尾胶原被覆组(P<0.05),培养3,5,7 d的乳酸脱氢酶漏出量低于聚氨酯对照组、鼠尾胶原被覆组(P<0.05);④结果表明,聚氨酯支架材料经纤维蛋白凝胶优化培养可用于生物人工肝反应器的构建。

关键词： 功能性水稻   有色稻   低谷蛋白水稻   高抗性淀粉水稻   富微营养水稻   生物反应器   育种  

摘要： 功能性水稻的开发与推广应用,对改善我国以稻米为主食人群的营养与健康状况、促进我国农业产业结构转变、提高农民种粮效益及助推乡村振兴具有重要意义。功能性水稻主要包括有色稻、低谷蛋白水稻、高抗性淀粉水稻、富微营养水稻和药物制造生物反应器水稻等5大类。有色稻由于种子果皮积累花色素苷而呈紫色或红褐色,有红米和黑米两大类,分别受2个和3个基因控制,是体弱者药食同源的重要滋补食品,国内已育成一大批有色稻品种推广应用。低谷蛋白水稻由于稻米谷蛋白含量低,适于肾病患者作主粮使用,目前中国和日本已育成多个品种用于商业化开发应用。高抗性淀粉水稻由于有部分淀粉无法被人体淀粉酶分解而不能被肠道吸收,可降低糖尿病患者餐后血糖峰值,已成为糖尿病患者重要的主食,目前国内已育成多个品种推广应用。富微营养水稻由于稻米特种维生素、有益微量元素等含量高而有益于不同缺素症患者治疗与保健,国内外已育成以“黄金大米”为代表的多个富微营养水稻品种。药物制造生物反应器水稻利用水稻为药用重组蛋白、多肽或其他生物活性物质生产平台,合成与提取目标功能成分物质,目前国内外都有成功报道,并已尝试进行商业化开发应用。全球对功能性水稻的需求日益增大,功能性水稻研究具有广阔前景。功能性水稻育种未来将从功能的单一型向复合型发展,由保健型向保健与辅助疗效相结合转变。多组学技术和常规育种相结合的方法,不断挖掘与创制新种质以培育功能性水稻新品种,是功能性水稻研究的发展方向。

关键词： 钨冶炼废水   污泥驯化   微生物菌群特性  

摘要： 研究钨冶炼废水膜生物反应器(MBR)过程中的微生物菌群特性,旨在为生物法处理钨冶炼废水处理效能的提高提供理论依据。试验结果表明:随盐度的增加污泥体积指数降低,而污泥沉降性能却提高;耐盐驯化期间,化学需氧量(COD)和氨氮(NH+4-N)去除率分别达到了86%~93%和80%~85%。微生物需分泌更多的SMP和EPS以抵抗高盐环境下所产生的高渗透压,变形菌门为微生物群落结构的核心菌门,陶厄氏菌属、副球菌属、假单胞菌属、亚硝化单胞菌属和盐单胞菌属为优势菌属。