活性污泥合成PHAs单体组分的调控方法

聚羟基烷酸酯（PHAs）是一类生物合成的环境友好高分子塑料，具有广泛应用前景。活性污泥合成PHAs可降低PHAs生产成本，实现废物资源化。PHAs的物化性质取决于其单体组分的结构和含量。基于优化PHAs产量的工艺研究，总结了调控活性污泥合成的聚羟基丁酸 羟基戊酸（PHBV）中羟基戊酰含量的工艺措施和生化原理。已有研究表明，好氧时，碳源类型决定PHBV中的单体组分;一般地，溶解氧浓度（DO）降低，PHBV中HV含量会增加;污泥来源、pH值以及碳源与氮磷浓度比的变化都会影响HV含量;各参数对PHAs组分的影响存在关联性。展望了调控活性污泥合成PHAs中单体组分的进一步研究方向。     

活性污泥合成聚羟基烷酸酯中单体组分的调控

聚羟基烷酸酯(PHAs)是一类生物合成的环境友好高分子塑料,具有广泛应用前景.活性污泥合成PHAs可降低PHAs生产成本,实现废物资源化.PHAs的物化性质取决于其单体组分的结构和含量.基于优化PHAs产量的工艺研究,总结了调控活性污泥合成的聚羟基丁酸-羟基戊酸(PHBV)中羟基戊酰含量的工艺措施和生化原理.已有研究表明,好氧时,碳源类型决定PHBV中的单体组分;一般地,溶解氧浓度(DO)降低,PHBV中HV含量会增加;污泥来源、pH值以及碳源与氮磷浓度比的变化都会影响HV含量;各参数对PHAs组分的影响存在关联性.展望了调控活性污泥合成PHAs中单体组分的进一步研究方向.     

PBS/PHAs的熔融行为和非等温结晶动力学

用示差扫描量热仪测定了聚羟基丁酸酯(PHAs)/聚丁二酸丁二醇酯(PBS)共混体系的熔融和非等温结晶动力学。结果发现:PHAs和PBS之间存在着相互作用。用Jeziorny方程对共混体系的非等温结晶动力学进行了研究,说明PHAs的加入对PBS的结晶动力学参数影响不大,PHAs的加入没有起到异相成核的作用,而是使PBS的结晶生长更加完善。用Kissinger方程计算了体系的结晶活化能,发现PHAs的加入使结晶活化能先升高后降低。     

PHAs在其他降解材料中的应用

综述了PHAs的种类、结构与性质,以及PHAs在PLA、PBS、PCL、PPC等可生物降解材料和组织工程及其他降解材料中的应用研究进展。     

ABR产酸-硫酸盐还原相颗粒污泥富集PHAs产生菌

为探究硫酸盐有机废水厌氧处理合成聚羟基脂肪酸酯(PHAs)的可行性，利用五隔室厌氧折流板反应器(ABR)以硫酸盐有机废水为底物富集PHAs产生菌合成PHAs，考察不同进水COD/SO₄^2-比值(12.5、9.3、4.0)对ABR产酸-硫酸盐还原相(第1、第2隔室)颗粒污泥PHAs合成效果的影响，进而探讨该体系中PHAs合成模式。结果表明：随进水COD/SO₄^2-比值降低，产酸-硫酸盐还原相的COD与SO₄^2-去除沿程后移，第1隔室呈现丁酸型代谢类型为主，第2隔室由乙酸型转为丁酸型代谢类型为主；颗粒污泥PHAs的高含量隔室由第1隔室后移至第2隔室，其中COD/SO₄^2-比值为9.3时，产酸-硫酸盐还原相中颗粒污泥PHAs产生菌大量富集、PHAs合成效果最好；在颗粒污泥中PHAs产生菌个体大，PHAs颗粒密集地布满整个菌体细胞；产酸-硫酸盐还原相中存在产酸菌(APB)、脂肪酸型硫酸盐还原菌(FSRB)、乙酸型硫酸盐还...     

由剩余污泥合成聚β-羟基脂肪酸酯的研究

研究了厌氧-好氧过程中微生物合成聚β-羟基脂肪酸酯(PHAs)和除磷的关系,利用在SBR反应器中除磷后的剩余污泥作为菌源,以葡萄糖为碳源合成PHAs.在2 h厌氧4 h好氧的反应周期中COD的去除率为81.7%.2 h厌氧过程中可溶性磷酸盐从6.23 mg/L升高到11.95 mg/L,污泥PHAs的含量由12.6 mg/gMLSS增加为73.6 mg/gMLSS,好氧阶段可溶性磷酸盐减少至1.47 mg/LL,污泥PHAs的含量降低为10.3 mg/gMLSS.好氧阶段除磷能力与厌氧过程污泥合成PHAs的含量有关.剩余污泥加入8g/L葡萄糖厌氧2 h后得到占污泥干重6.1%的PHAs,1HNMR谱图和FT-IR谱图表明其结构为PHBV.     

聚羟基烷酸酯的研究进展

微生物发酵合成的聚羟基烷酸酯(PHAs)作为最具有发展潜力的新型生物高分子材料之一,备受关注。本文介绍了近几年来有关PHAs的生物合成、分离纯化、性能改进、生产与应用现状等方面研究的最新进展,探讨了这一领域未来可能的发展热点和动向。     

利用有机废水生产聚羟基烷酸(PHAs)的进展

聚羟基烷酸（PHAs,polyhydroxyalkanoates）是由微生物经β-羟基烷酸聚合而成的一类高分子化合物的总称,它具有优良的生物可溶性、生物可降解性、光学活性、压电性等品质。本文综述了近年来利用有机废水生产PHAs的研究进展。     

可生物降解塑料聚-β=羟基丁酸酯（PHB）

聚羟基链烷酯(Polyhydroxyalkanoate，PHAs)是一类微生物聚酯的简称，由于PHAs不仅具有化学合成塑料的特性，还具有一些特殊性能，如生物可降解性、生物相容性、光学活性以及在生物合成过程中可利用再生原料等，因而在医学、农业、电子和食品等工业领域具有广阔的应用前景，可望成为一种替代传统塑料的新型高分子材料，为解决“白色污染”带来希望。目前已鉴定的PHAs约有40种，其中PHB是PHAs的典型代表。它存在于多种微生物中，具有广泛的应用前景。     

混合液回流比对A/A/O工艺反硝化除磷的影响

以生活污水培养驯化污泥的小试规模A/A/O工艺为研究对象,进行了混合液回流比为100%、200%和300%时对反硝化除磷的影响研究,并利用厌氧/缺氧批式试验方法对污泥特性进行单独考察。结果表明,随着混合液回流比的增大,缺氧除磷在系统除磷所起的作用、反硝化聚磷菌缺氧利用单位聚羟基链烷酸（PHAs）的吸磷量和反硝化数量出现先升高后下降,厌氧合成单位PHAs的释磷量和好氧利用单位PHAs的吸磷量并没有受到影响,以200%时反硝化除磷和系统脱氮除磷效果为最好,过高或过低NO₃-N浓度均会影响反硝化聚磷菌的缺氧吸磷速率和PHAs降解速率,但并没有影响其本身所固有的特性。     

Polyhydroxyalkanoates,a family of natural polymers,and their applications in drug delivery

Polyhydroxyalkanoates (PHAs) are natural biopolymers produced by various microorganisms as a reserve of carbon and energy. PHA synthesis generally occurs during fermentation under nutrient limiting conditions with excess carbon. There are two main types of PHAs, short chain length PHAs (scl‐PHAs) and medium chain length PHAs (mcl‐PHAs). The mechanical and thermal properties of PHAs depend mainly on the number of carbons in the monomer unit and its molecular weight. PHAs are promising materials for biomedical applications because they are biodegradable, non‐toxic and biocompatible. The large range of PHAs, along with their varying physical properties and high biocompatibility, make them highly attractive biomaterials for use in drug delivery. They can be used to produce tablets, micro‐ and nanoparticles as well as drug eluting scaffolds. A large range of different PHAs have been explored and the results obtained suggest that PHAs are excellent candidates for controlled and targeted drug delivery systems. © 2015 Society of Chemical Industry     

Bioconversion of residual soybean oil into polyhydroxyalkanoates

The aim of this study is to evaluate the bioconversion of residual soybean oil (RSO) into polyhydroxyalkanoates (PHAs) by selecting microorganism and fermentation condition in order to increase PHAs production. PHAs production by Cupriavidus necator IPT 026 using glucose (PHA 1) and RSO (PHA 2) as substrate is 1.15 ± 0.21 and 2.84 ± 0.04 g L^?1, respectively. FTIR spectra of PHAs were similar to data reported in literature. PHAs presented low crystallinity (PHA 1: 42.69%; PHA 2: 46.44%), high thermal stability (PHA 1: 271.78 °C; PHA 2: 272.52 °C), and low M_W (PHA 1: 140.69 kDa; PHA 2: 254.54 kDa). PHAs produced by RSO are potential candidates for industrial applications, especially ones that demand higher temperatures. This is the first study on the production and characterization of PHAs obtained by C. necator IPT 026 in culture with RSO. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46255.     

Production of polyhydroxyalkanoates: the future green materials of choice

Polyhydroxyalkanoates (PHAs) have recently been the focus of attention as a biodegradable and biocompatible substitute for conventional non degradable plastics. The cost of large‐scale production of these polymers has inhibited its widespread use. Thus, economical, large‐scale production of PHAs is currently being studied intensively. Various bacterial strains, either wild‐type or recombinant have been utilized with a wide spectrum of utilizable carbon sources. New fermentation strategies have been developed for the efficient production of PHAs at high concentration and productivity. With the current advances, PHAs can now be produced to a concentration of 80 g L^?1 with productivities greater than 4 g PHA L^?1 h^?1. These advances will further lower the production cost of PHAs and allow this family of polymers to become a leading biodegradable polymer in the near future. This review describes the properties of PHAs, their uses, the various attempts towards the production of PHAs, focusing on the utilization of cheap substrates and the development of different fermentation strategies for the production of these polymers, an essential step forward towards their widespread use. Copyright © 2010 Society of Chemical Industry     

真氧产碱杆菌利用短链有机酸合成聚羟基烷酸酯

研究了真氧产碱杆菌利用单一以及混合短链有机酸作为碳源进行聚羟基烷酸酯(PHAs)的生物合成. 不同的碳氮浓度比对产物的形成有较大影响；在同样的碳源浓度下，较低氮源浓度更加有利于产物的合成；当短链有机酸浓度为8 g/L、硫酸铵浓度为0.3 g/L时对PHAs的合成最为有利.在4种短链有机酸分别单独用作碳源时，乳酸的消耗速度最快，其次为乙酸、丁酸以及丙酸；在单酸发酵条件下，丁酸的PHAs产量最高(2.72 g/L). 通过比较摇瓶以及5 L罐水平的混合酸发酵发现，发酵罐中的各项发酵指标均优于摇瓶. 研究还发现，真氧产碱杆菌在利用丙酸为碳源进行产物合成时，在发酵后期还伴随有乙酸产生.     

PVC modification with biobased poly(hydroxyalkanoates)

Supported by numerous calculated and empirical data, a miscibility between polyvinylchloride (PVC) and biobased poly(hydroxyalkanoates) (PHAs), PHAs along with its utilization in plasticization, toughening, and processing improvement is discussed in unplasticized and plasticized (semirigid to flexible) PVC compounds. The long‐term thermal stability of PVC stabilized with BaZn salts is shown to be improved in the presence of PHAs and the short‐term stability (initial color hold) slightly reduced. The biobased PHAs are also shown to improve UV stability of PVC by offsetting the yellowing of PVC and not causing additional photodegradation. The transparence and durability of PVC are found to be unaffected by the presence of minor phase of otherwise biodegradable PHA. The discussed PHAs offer a new, ecologically attractive, and simplified approach to PVC formulation in which multiple processing and modifying additives could be replaced with a single product, eliminating both undesirable additive interactions and the need to stabilize unstable ingredients. J. VINYL ADDIT. TECHNOL., 21:259–271, 2015. © 2014 Society of Plastics Engineers     

Wood flour/polylactide biocomposites toughened with polyhydroxyalkanoates

Polylactide (PLA)‐based wood–plastic composites (WPCs) were successfully manufactured by extrusion blending followed by injection molding. The effects of polyhydroxyanoates (PHAs) on the mechanical and thermal properties and the morphologies of the PLA‐based WPCs were investigated with mechanical testing, thermal analysis, and scanning electronic microscopy (SEM). The inclusion of PHAs in the PLA‐based WPCs produced an increase in the impact resistance and a decrease in the tensile strength. The brittle–ductile transition of the impact strength for the PLA‐based WPCs toughened with PHAs was confirmed when the wood flour content was between 15 and 35 wt %. SEM images showed that the fracture surfaces of the PLA‐based WPCs toughened with PHAs were rougher than that of their nontoughened counterparts. The ternary PLA‐based WPCs exhibited ductile fracture during mechanical testing. Differential scanning calorimetry (DSC) showed that addition of PHAs into the composites caused deviations of the cold crystallization temperature and melting temperature of PLA. Thermogravimetric analysis indicated that the PHAs reduced the thermal stability of the PLA‐based WPCs. PHAs can be a green toughening agent for PLA‐based WPCs. The specific properties evidenced by the biocomposites may hint at their potential application, for example, in the automotive industry and civil engineering. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

新型环境友好型热塑材料聚羟基烷酸的研究进展

在对聚羟基烷酸（PHAs）的结构和性质介绍的基础上，从实际工业应用的角度综述了国内外近年有关它的生物合成、提取及应用中取得的成果与存在的问题，展望了这一新材料的发展趋势与应用前景。     

Polyhydroxyalkanoates: Recent Advances in Their Synthesis and Applications

Polyhydroxyalkanoates (PHAs) are microbial biopolymers (polyesters) that have a wide range of functions and applications. They serve in nature mainly as carbon and energy storage materials for a variety of microorganisms. In past decades, their utilization has attracted much attention, from commodities and degradable plastics to specialty performance materials in medicine. PHA biosynthesis has been well understood, and it is now possible to design bacterial strands to produce PHAs with desired properties. The substrates for the fermentative production of PHAs are very manifold: some are derived from food‐based carbon sources (e.g., fats and oils (triglycerids)), thus raising concerns with regard to the sustainability of their productions in terms of crop area and food. In addition, hemicellulose hydrolysates, crude glycerol, and methanol are very promising carbon sources for the sustainable production of PHAs. The integration of PHA production within a modern biorefinery is an important issue and can result in a simultaneous production of biofuels and bioplastics. Furthermore, many chemical‐synthetic procedures by means of efficient catalysts can give access to a variety of PHAs. This article summarizes recent developments in these fields and emphasizes the importance of a sustainable PHA‐based industry. Practical Applications: Practical applications of the microbial polyesters PHAs are, for example, a variety of sustainably produced commodities as well as special applications in (bio)medicine, for example, tissue engineering.