混合菌群合成聚羟基脂肪酸酯研究进展

聚羟基脂肪酸酯（PHA）是微生物体内合成的可生物降解塑料,可以作为化学塑料的替代品。利用纯培养微生物发酵的合成方法由于使用葡萄糖等优质底物及过程需灭菌等原因,产品成本较高,严重制约了PHA的广泛使用;混合菌群利用废弃物合成PHA有效降低了纯培养方法的生产成本,因此受到人们越来越多的关注。本文对混合菌群合成PHA的历史沿革、合成原理、生产工艺、提取方法等方面进行了系统综述。回顾了混合菌群合成PHA的发展历程,简述了两种主要的合成机理,介绍了不同底物合成PHA的代谢途径,重点阐述了混菌合成PHA的三段式工艺和产物提取方法,同时也对新近的研究动态进行了分析总结。指出提高混菌浓度与利用实际废弃物的能力将成为未来研究的关键。     

多聚羟基烷酸的发酵生产研究进展

多聚羟基烷酸（PHA）是一类有良好应用前景的生物可降解塑料，为降低其生产成本，国内外科研工作者进行了大量的研究，本文着重对PHA的发酵生产和提取工艺进行了介绍。     

人白细胞介素-2提纯样品中PHA残留量测定

应用SDS梯度聚丙烯酸胶凝胶电泳法、淋巴细胞增殖法和显微血凝法对三批提纯人IL-2样品中的残留PHA作了检测·结果表明我们提纯工艺对去除PHA效果较好，PHA残留浓度低于25μg／ml，PHA总量从提纯前的600mg降为0．75mg以下．去除率达99％以上，另外，我们还对三种检测方法进行了比较，认为显微血凝法是一种简便、特异、灵敏的方法。     

PHA/PBC聚合物合金的制备及其性能

聚羟基脂肪酸酯(PHA)具有优异的力学性能、生物相容性和阻隔性能，作为一种生物降解高分子材料在包装材料、组织工程和电学等领域得到广泛应用。结晶速率慢和韧性差限制了PHA应用领域的拓展。通过熔融混合的方法制备了一系列不同聚碳酸丁二酯(PBC)含量的PHA聚合物合金。采用差示扫描量热仪、热重分析仪、万能试验机、扫描电子显微镜和接触角测量仪等表征手段重点考察了PBC含量对PHA/PBC合金结晶、热分解、力学和亲疏水等性能的影响。结果表明，PBC的加入可以提高PHA/PBC合金的结晶峰温度，少量PBC均匀分散在PHA基体中可为成核中心，PBC质量分数为10%的PHA/PBC合金具有最高的结晶度。随着PBC含量的增加，PHA/PBC合金由脆性断裂向韧性断裂转变，PBC质量分数为90%的PHA/PBC合金的断裂伸长率分别是PHA和PBC的143倍和1.6倍，主要因为三柠檬酸三丁酯(TBC)对合金的增塑作用。另外，通过改变PBC含量还可以调控PHA/PBC合金热稳定性和亲疏水性。     

利用淀粉化废水驯化活性污泥合成聚-β-羟基脂肪酸酯及其表征

研究了活性污泥利用淀粉酸化废水合成聚-β-羟基脂肪酸酯(PHA)及其表征。结果表明，淀粉废水酸化产物为丁酸、乙酸、丙酸、乙醇、戊酸。以此酸化产物为碳源经活性污泥合成PHA，合成结束后活性污泥中PHA含量为34.7％。活性污泥中PHA采用氯仿提取，并用核磁共振(NMR)、热失重(TG)、差热(DSC)方法对其结构和热性质...     

聚羟基脂肪酸酯的鉴定及检测方法研究进展

聚羟基脂肪酸酯(简称PHA)是由很多细菌合成的一种细胞内聚酯,由于具有生物可降解性、生物相容性、压电性等许多优良性能,在众多领域,如生物降解性包装材料、组织工程材料、缓释材料以及电学材料等方面得到广泛应用,引起了科研领域和工业界的广泛兴趣。对PHA的物理、化学性质以及鉴定及检测方法的研究进行了综述,回顾有关PHA的鉴定及检验方法的同时介绍了近期取得的研究进展。     

厨余垃圾生物合成聚羟基脂肪酸酯研究进展

基于利用厨余垃圾作为合成挥发性脂肪酸（VFAs）的原始基质，既可以增加厨余垃圾资源化利用新途径，又可以降低聚羟基脂肪酸酯（PHA）合成成本，有利于厨余垃圾合成PHA产业化发展的优势，概述了PHA的应用领域和类型，总结了厨余垃圾合成PHA工艺路线和PHA前体物（VFAs）合成阶段与PHA 合成阶段的内在合成机制，重点汇总了利用厨余垃圾合成VFAs过程和利用VFAs合成PHA过程的重要工艺参数。最后，对厨余垃圾合成PHA 研究方向进行了展望。     

VFAs组分调控对合成PHA影响研究进展

介绍了有机酸复配合成PHA的国内外研究现状,阐明了VFAs合成PHA的代谢途径,得出PHA的单体组成直接受VFAs中奇偶数酸的影响。围绕VFAs组分的调控策略,论述了有机废弃物厌氧发酵过程中VFAs组分的变化规律,归纳了不同组分VFAs合成PHA的性能和产率变化,指出提高奇数酸质量分数、增加HV单体占比是优化PHA性能的重要方式。通过归纳总结VFAs的各种调控策略,明确了合成优质PHA的研究方向。     

聚β–羟基烷酸酯的改性研究进展

介绍了聚β-羟基烷酸酯的性能。综述了近年来针对PHA的缺点进行改性的方法:生物合成改性;与生物活性无机材料的复合改性及表面改性。展望了改性后的PHA在组织工程及医用材料中的应用。     

聚β-羟基烷酸酯的改性研究进展

介绍了聚β-羟基烷酸酯的性能.综述了近年来针对PHA的缺点进行改性的方法:生物合成改性;与生物活性无机材料的复合改性及表面改性.展望了改性后的PHA在组织工程及医用材料中的应用.     

复合菌群利用模拟APG协同FNA预处理剩余污泥水解液合成PHA

为探究亚硝酸（FNA）预处理协同烷基糖苷（APG）处理剩余污泥水解液合成聚羟基烷酸酯（PHA）的可行性,本文启动接种两种不同污泥的序批式反应器（SBR）富集PHA产生菌,研究活性污泥复合菌群以模拟APG协同FNA预处理剩余污泥的水解液为底物的PHA合成效果;并采用批次合成实验,考察pH、C/N和C/P对PHA合成量的影响。结果表明：与接种污水厂二沉池污泥的反应器（SBR^#1）相比,接种以葡萄糖为底物驯化成熟的产PHA混合菌的反应器（SBR^#2）在30天时得到的PHA合成量较高;随着富集时间的推移,到117天时,接种污水厂二沉池污泥得到的PHA产生菌性能更优。PHA合成的最佳条件为：pH=8,C/P=100∶0.03,C/N=125∶1。在此条件下,PHA合成量最大,为57.34%。以实际FNA预处理协同APG处理剩余污泥水解液为底物时,PHA的累积合成量为24.43%。该研究结果可丰富污泥合成PHA技术方法,为污泥的处理和资源化利用提供技术支持。     

pH对嗜盐混合菌发酵挥发性有机酸混合物合成PHA的影响

嗜盐混合菌发酵生产聚羟基脂肪酸酯（polyhydroxyalkanoate,PHA）具有免灭菌程序、产量高、易提取等优势而被广泛关注。集中考察了pH对嗜盐混合菌（MMCs）发酵混合挥发性有机酸（VFA）生产PHA的影响。研究结果表明,在6.5～8.2范围内pH对PHA合成没有明显影响,过高或者过低的pH都会降低PHA合成速率和VFA的吸收速率。发酵体系的pH影响了嗜盐MMC的PHA产量,但是在酸性和碱性条件下却存在不同的影响机制。碱性环境增大了VFA的解离程度,导致MMC对底物的吸收耗费大量的能量,造成VFA吸收速率的下降。这一作用在pH升高至9.2以上时表现显著。酸性环境下,分子态VFA进入细胞后改变了胞内的pH,降低了相关酶和蛋白质的活性,从而影响了底物的利用。当pH=5.2时微生物代谢及底物利用能耗量降低,导致PHA胞内降解利用率降低,刺激了PHA合成量的提高。PHA组分受pH影响不大,初始pH=5.2～10.2时羟基脂肪酸戊酯（hydroxyvalerate,HV）所占比例维持在34.9%～38.3%范围内。本研究对于进一步利用嗜盐MMC发酵含有混合VFA的废弃物生产PHA具有重要的指导意义。     

Start up of biological sequencing batch reactor (SBR) and short‐term biomass acclimation for polyhydroxyalkanoates production

BACKGROUND: The adaptation/selection of mixed microbial cultures under feast/famine conditions is an essential step for polyhydroxyalkanoates (PHA) production. This study investigated the short‐term adaptation of a mixed microbial culture (activated sludge) during the start up of a sequencing batch reactor (SBR). RESULTS: Four different SBR runs were performed starting from different inocula and operated at the same organic load rate (8.5 gCOD L^?1 d^?1) and hydraulic retention time (1 day). At 3–7 days from SBR start up, the selected biomass was able to store PHA at comparable rate and yield with those obtained after long‐term acclimation. Independently from the time passed, a short feast phase was the key parameter to obtain PHA storage at high rate and yield in the following accumulation stage (244 mgCOD g^?1CODnonPolym h^?1 for specific storage rate and 48% COD COD^?1 as PHA content in the biomass). The DGGE profiles showed that the good storage performance and the structure of the microbial community were not fully correlated. CONCLUSIONS: The results suggest a new strategy for operating the PHA accumulation stage directly in the SBR, after very short biomass adaptation, instead of using two separate reactors for biomass enrichment and PHA accumulation, respectively. © 2012 Society of Chemical Industry     

1,3-二羟基丙酮的合成与应用研究进展

1,3-二羟基丙酮作为重要的化工医药中间体,广泛应用于化工、医药、化妆品和食品领域。主要综述了1,3-二羟基丙酮的合成方法,包括化学合成法和微生物合成法,并介绍了其在化工与医药领域的最新应用进展。     

SRT对富集高聚PHA能力嗜盐MMC的影响

调控菌群富集过程的工艺参数,富集具有高PHA积累能力的混合菌(MMC)是发酵生产PHA的第一步也是最重要的一步。采用批式培养条件,集中研究了污泥停留时间(SRT)对PHA积累菌群的富集作用。研究结果表明SRT影响富集MMC的底物降解速率(q_S),微生物积累PHA的速率(q_P)和PHA积累能力。长SRT(SRT4d)导致了较低的q_S,q_P和PHA细胞含量;过短的SRT(SRT1d)则降低了MMC的PHA转化率(Y_PHA/S)和PHA积累能力,刺激了非PHA积累菌群的快速增殖。研究确定的最佳SRT为2d,在此条件下富集的MMC最大PHA积累量可达细胞干重的56%。研究证明了SRT在选择嗜盐MMC中的重要作用,为快速富集PHA积累能力MMC奠定基础。     

Morphologies and mechanical properties of polylactide blends with medium chain length poly(3‐hydroxyalkanoate) and chemically modified poly(3‐hydroxyalkanoate)

Blends of bacterial poly(3‐hydoroxyalkanoate) (PHA) with a medium‐length side chain and polylactide (PLA), and blends of the chemically modified PHA (ePHA) with PLA, were prepared. The morphologies, some physical properties, and thermal behavior of the blends based on PLA were investigated by electron microscopies, testing machines, and a differential scanning calorimeter, respectively. A blend of uncrystallized rubbery second components, PHA and ePHA, produced an increase in the impact toughness of the PLA blends in contrast to a decrease in the tensile strength value. PHA, especially, with an inserted epoxy group side chain was more effective in improving the morphology and the physical properties than PHA. The ePHA particles existed in the PLA domain as a dispersed phase having a size of 0.1–1 μm. The results of the biodegradation test demonstrated that the PLA blends still maintained their biodegradability and were more accessible to hydrolysis and microbial attack, resulting in a greater weight loss than the pure PLA. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2363–2369, 2004     

Production of polyhydroxyalkanoates by batch and fed-batch cultivations of <Emphasis Type="Italic">Bacillus megaterium</Emphasis> from acid-treated red algae

Polyhydroxyalkanoates (PHAs) are linear polyesters synthesized by microbial fermentation of various substrates. PHAs are accumulated in microbial cells in order to store carbon and energy for future use. We used acid-pre-treated red alga (Gelidium amansii) as a cheap, abundant carbon source to produce PHA via batch and fed-batch cultivation of Bacillus megaterium KCTC 2194. After acid treatment of 10% (w/v) G. amansii, 25.5 g/L galactose, 3.6 g/L glucose, 6 g/L 5-HMF, and 1.05 g/L levulinic acid were formed. In batch culture at pH 7, the dry cell weight (DCW) and PHA content increased to 5.5 g/L and 51.4%, respectively. The cell concentration was enhanced by fed-batch cultivation using two feeding strategies: pH-stat and intermittent feeding. When the pH-stat feeding strategy was employed to add concentrated hydrolysate to the fermentor, DCW increased to 8.2 g/L, with 53.2% PHA content. When concentrated hydrolysate was fed using the intermittent feeding strategy, higher DCW (10.1 g/L) was obtained, along with a slight increase of PHA content to 54.5%. This study demonstrates that red algae could be used after simple acid treatment, to produce PHA without steps for enzymatic hydrolysis and inhibitor removal.     

Uranyl ion binding properties of poly(hydroxamic acid) hydrogels

Summary   Poly(hydroxamic acid) (PHA) hydrogels, obtained from the synthesis of crosslinked poly(acrylamide) (PAAm) gels have been prepared, and their uranyl ion binding properties from two different sources were investigated. Swelling and binding parameters of crosslinked PHA gels were determined from swelling and uranyl ion adsorption studies. The effect of uranyl ion concentration, pH, temperature and mass of adsorbent on the uranyl ion adsorption were examined. The binding process between PHA and uranyl ions complies with the S type adsorption according to Giles classification. Free energies of the adsorptions found as negative values indicating spontaneous adsorption process. The structure and hydrophilicity of the used crosslinkers, the ionogenity of PHA polymers and the source of uranyl ions found to be effective on the swelling and binding behaviors of PHA hydrogels. Received: 3 March 2001 / Revised version: 30 June 2001 / Accepted: 9 July 2001