新型生物材料PHAs用于污水固相脱氮处理

介绍了生物可降解聚合体PHAs（聚羟基脂肪酸酯）的特点及其在污水反硝化脱氯中的应用。与传统液相有机基质脱氮相比，PHAs固相基质脱氮具有很多优点：为脱氮过程提供了连续的资源；有利于生物膜的培养和生成；PHAs释放的不溶有机碳不会对水质产生潜在的危害。PHAs固相基质脱氮技术已显现出了良好的应用前景。     

嗜盐微生物底盘细胞：应用和前景

嗜盐微生物是一种耐高盐的微生物,有细菌、古菌、藻类等。其中的中度嗜盐菌耐受30~150g/L的氯化钠,有很高的研究价值和应用前景。嗜盐微生物可以在海水中生长,有的同时嗜碱,尤其不少嗜盐细菌在矿物培养基中生长迅速,具有作为底盘细胞的优势。随着近年来对嗜盐微生物分子操作工具的不断开发,嗜盐细菌的改造工作得到了迅猛发展。工程化的嗜盐微生物已经可以用于合成数种聚羟基脂肪酸酯（PHA）,也用于大规模生产多种聚合物、蛋白质、小分子化合物、氨基酸和化妆品原料。合成生物学技术的使用也使嗜盐微生物实现了可控形变, 有利于更多的胞内产物的合成和下游的细胞分离。根据嗜盐微生物,特别是嗜盐细菌的特点和研究进展,本文提出了以嗜盐微生物作为底盘细胞的“下一代工业生物技术”,使发酵工业实现开放式的节能、节水、连续、全自动的过程,减少微生物大规模培养的复杂程度和对设备的高要求,同时能联产生产多种产品,大幅度降低工业生物技术的制造成本,提高产品的竞争性。     

强化生物除磷系统胞内聚合物测定方法优化

为优化强化生物除磷系统胞内PHA、糖原以及多聚磷酸盐颗粒的测定方法,采用色谱与化学分析相结合的方法进行研究.其中,PHA的测定采用气相色谱法,糖原的测定采用稀盐酸消解加葡萄糖试剂盒法,多聚磷酸盐采用过硫酸钾氧化和钼锑抗光度法,经过方法优化得出4%酸化甲醇消解20h是提高PHA回收量的最佳条件;糖原在0.6mol/LHCl条件下消解5h提取量最大,临床中的葡萄糖氧化酶法试剂盒可以应用到本实验中;在120℃下氧化30min条件下多聚磷酸盐颗粒可以最大回收.经过加标回收实验等对这3个方法进行精密度、准确度分析,结果显示,在这3个条件下的3种方法都具有很高的精密度或准确度,而且简单易行,适合实验室及生产实践中的应用.     

Exploiting olive oil mill effluents as a renewable resource for production of biodegradable polymers through a combined anaerobic–aerobic process

BACKGROUND: The performance of a three‐stage process for polyhydroxyalkanoate (PHA) bioproduction from olive oil mill effluents (OME) has been investigated. In the first anaerobic stage OME were fermented in a packed bed biofilm reactor into volatile fatty acids (VFAs). This VFA‐rich effluent was fed to the second stage, operated in an aerobic sequencing batch reactor (SBR), to enrich mixed cultures able to store PHAs. Finally, the storage response of the selected consortia was exploited in the third aerobic stage, operated in batch conditions. RESULTS: The anaerobic stage increased the VFA percentage in the OME from 18% to ～32% of the overall chemical oxygen demand (COD). A biomass with high storage response was successfully enriched in the SBR fed with the fermented OME at an organic load rate of 8.5 gCOD L^?1 d^?1, with maximum storage rate and yield (146 mgCOD gCOD^?1 h^?1 and 0.36 COD COD^?1, respectively) very similar to those obtained with a synthetic VFA mixture. By means of denaturing gradient gel electrophoresis (DGGE) analysis, different bacterial strains were identified during the two SBR runs: Lampropedia hyalina and Candidatus Meganema perideroedes, with the synthetic feed or the fermented OMEs, respectively. In the third stage, operated at increasing loads, the maximum concentration of the PHA produced increased linearly with the substrate fed. Moreover, about half of the stored PHAs were produced from substrates other than VFAs, mostly alcohols. CONCLUSION: The results obtained indicate that the process is effective for simultaneous treatment of OME and their valorization as a renewable resource for PHA production. Copyright © 2009 Society of Chemical Industry     

Production and characterization of poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) co‐polymer by a N2‐fixing cyanobacterium,Nostoc muscorum Agardh

BACKGROUND: Poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) [P(3HB‐co‐3HV)] co‐polymer has immense potential in the field of environmental and biomedical sciences as biodegradable and biocompatible material. The present study examines a filamentous N₂‐fixing cyanobacterium, Nostoc muscorum Agardh as a potent feedstock for P(3HB‐co‐3HV) co‐polymer production and characterization of co‐polymer film for commercial applications. RESULTS: Under photoautotrophic growth conditions, N. muscorum Agardh accumulated the homopolymer of poly‐β‐hydroxybutyrate (PHB), whereas synthesis of P(3HB‐co‐3HV) co‐polymer was detected under propionate‐ and valerate‐supplemented conditions. Exogenous carbons such as acetate, fructose and glucose supplementation with propionate/valerate was found highly stimulatory for the co‐polymer accumulation; the content reached 58–60% of dry cell weight (dcw) under P‐/N‐deficiencies with 0.4% acetate + 0.4% valerate supplementation, the highest value reported so far for P(3HB‐co‐3HV) co‐polymer‐producing cyanobacterial species. The material properties of the films were studied by mechanical tests, surface analysis and differential scanning calorimetry (DSC). CONCLUSION: N. muscorum Agardh, a photoautotrophic N₂‐fixing cyanobacterium, emerged as a potent host for production of P(3HB‐co‐3HV) co‐polymer with polymer content 60% of dry cell weight. The material properties of the films were found to be comparable with that of the commercial polymer, thus advocating its potential applications in various fields. Copyright © 2012 Society of Chemical Industry     

Method for rapid control of bacterial PHA production through thermogravimetric analysis

BACKGROUND: PHA (polyhydroxyalcanoates) are highly promising biopolymers, which are produced as storage material inside the cells by several microorganisms. During microorganism cultivations numerous parameters can be measured (DW, pH, glucose concentration, etc.) but the most important, e.g. PHA content in cells, can only be viewed by qualitative techniques or after long and tricky extraction for a quantitative approach. RESULTS: A thermogravimetric method was studied based on the difference between the degradation temperatures of PHA, at 210 °C, and those of the rest of the cells, the degradation of which begins at 250–260 °C. Proofs of the accuracy, robustness and reproducibility of this method were achieved. CONCLUSION: An optimized thermogravimetric method for PHA analysis inside cells has been described. This method allows a precise appreciation of PHA content in less than 70 min and with only 1 mL of withdrawn sample. Copyright © 2011 Society of Chemical Industry     

厌氧HRT对A/O除磷工艺的影响

为系统考察厌氧水力停留时间（AHRT）对生物除磷效果的影响,本文以实际生活污水作为进水,在实验室连续流厌氧／好氧（A／O）除磷系统稳定运行的基础上,统计了不同AHRT下系统除磷效果及胞内贮存物的变化。设计批式实验,考察了AHRT较长情况下生物增强除磷代谢过程,针对实验过程中出现的厌氧聚羟基链烷酸酯（PHAs）分解和厌氧糖原合成现象,提出聚磷不足情况下聚磷菌代谢的假想模式。最后根据实验结果指出A／O除磷工艺AHRT的确定应以PHAs的合成量最大作为控制目标。     

聚羟基烷酸酯降解包装材料的生物合成及进展

目的综述聚羟基烷酸酯(Polyhydroxyalkanoates,PHAs)的生物合成工艺、影响因素及其在包装工业领域的应用研究进展,以期优化其生产工艺、降低生产成本、提高PHAs的产量。方法通过对近年来国内外研究现状和研究成果的分析和总结,介绍PHAs的生物合成工艺、影响PHAs产量的主要因素及在包装方面的应用。结论好氧瞬时供料法合成的PHAs产量高于微好氧-好氧工艺;底物种类、C/N值、pH值、溶解氧浓度和合成温度对生物合成PHAs的产量和成分比例都有很大影响;PHAs作为可降解材料在包装领域具有广阔的应用前景,未来的重点研究方向是优化PHAs的合成工艺和影响因素,降低其生产成本,提高产量和产品性能。     

Vimentin Cytoskeleton Architecture Analysis on Polylactide and Polyhydroxyoctanoate Substrates for Cell Culturing

Polylactide (PLA), widely used in bioengineering and medicine, gained popularity due to its biocompatibility and biodegradability. Natural origin and eco-friendly background encourage the search of novel materials with such features, such as polyhydroxyoctanoate (P(3HO)), a polyester of bacterial origin. Physicochemical features of both P(3HO) and PLA have an impact on cellular response 32, i.e., adhesion, migration, and cell morphology, based on the signaling and changes in the architecture of the three cytoskeletal networks: microfilaments (F-actin), microtubules, and intermediate filaments (IF). To investigate the role of IF in the cellular response to the substrate, we focused on vimentin intermediate filaments (VIFs), present in mouse embryonic fibroblast cells (MEF). VIFs maintain cell integrity and protect it from external mechanical stress, and also take part in the transmission of signals from the exterior of the cell to its inner organelles, which is under constant investigation. Physiochemical properties of a substrate have an impact on cells’ morphology, and thus on cytoskeleton network signaling and assembly. In this work, we show how PLA and P(3HO) crystallinity and hydrophilicity influence VIFs, and we identify that two different types of vimentin cytoskeleton architecture: network “classic” and “nutshell-like” are expressed by MEFs in different numbers of cells depending on substrate features.