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。     

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。     

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。     

微生物塑料的研究现状及应用前景

综述了近几年来国内外聚羟基脂肪酸酯(PHAs)微生物合成的研究进展,同时对PHAs的应用前景进行了展望。     

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...     

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。     

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.     

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。     

河流沉积物中多环芳烃(PAHs)类化合物提取技术的比较研究

河流沉积物中的多环芳烃(PHAs)威胁着河流底栖生物以及人类的健康,不断发展的检测技术可以帮助人类更好地研究PAHs类污染物的沉积、迁移、转化规律。文章综述了河流沉积物中PHAs的前处理提取技术,对索氏提取、自动索氏提取、固液搅拌萃取、UAE、MAE、SFE、ASE和吹扫捕集法等提取方法的提取条件、成本和效率进行了比较。     

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     

Polyhydroxyalkanoate‐based drug delivery systems

Microbial polyhydroxyalkanoates (PHAs) have been a subject of significant research interest in the past few decades. The recent development of novel functionalized PHAs has opened up new possibilities to combine the good biocompatibility of PHA‐based drug delivery systems to, for example, improve drug loading and release properties, targeting or imaging functionalities. This mini‐review presents some recent scientific developments in the preparation of functionalized PHAs, PHA–drug and PHA–protein conjugates, multifunctional PHA nanoparticles and micelles as well as biosynthetic PHA particles for drug delivery. These developments in combination with the generally excellent biocompatibility of PHA materials are expected to further expand the interest in PHA materials for drug delivery and other therapeutic applications. © 2016 Society of Chemical Industry     

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.     

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     

Surface Modification of Polyhydroxyalkanoates toward Enhancing Cell Compatibility and Antibacterial Activity

Biomaterials for in vivo application should induce positive interaction with various histocytes and inhibit bacteria inflection as well. Cells and/or bacteria response to the extracellular environment is therefore the basic principle to design the biomaterials surface in order to induce the specific biomaterial–biological interaction. Polyhydroxyalkanoate (PHAs) are of growing interests because of their natural origin, biodegradability, biocompatibility, and thermoplasticity; however, quite inert and intrinsic hydrophobic characteristics have hindered their extensive usage in medical applications. Surface modification of PHAs tailors the chemistry, wettability, and topography without altering the bulk properties, and introduces specific proteins/peptides and/or antibacterial agents to mediate cell–matrix interactions. This review describes the recent developments on the surface modification of PHAs to construct cell compatible and antibacterial surfaces.     

RETRACTED ARTICLE: Towards understanding polyhydroxyalkanoates and their use

It is fact that Polymers and their products have changed the face of the world in all the field of the technology. They are the future of the coming up generation of the research of the world. But this is also fact that these synthetic non biodegradable polymers have created a tough situation for the living being for a healthy life. Polyhydroxyalkanoates are polyesters produced by bacteria as intracellular storage materials in response to a variety of nutritional and environmental conditions, such as nitrogen limitation Polyhydroxyalkanoates (PHAs) are gaining increasing attention in the biodegradable polymer market due to their promising properties such as high biodegradability in different environments, not just in composting plants, and processing versatility. Indeed among biopolymers, these biogenic polyesters represent a potential sustainable replacement for fossil fuel-based thermoplastics. Most commercially available PHAs are obtained with pure microbial cultures grown on renewable feedstocks (i.e.glucose) under sterile conditions but recent research studies focus on the use of wastes as growth media.PHA can be extracted from the bacteria cell and then formulated and processed by extrusion for production of rigid and flexible plastic suitable not just for the most assessed medical applications but also considered for applications including packaging, moulded goods, paper coatings, non-oven fabrics, adhesives, films and performance additives. The present paper reviews the PHAs, their main properties, processing aspects, commercially available ones, as well as limitations and related improvements being researched,with specific focus on potential applications of PHAs in packaging.     

Integrated Biorefinery Design with Techno-Economic and Life Cycle Assessment Tools in Polyhydroxyalkanoates Processing

To support and move toward a sustainable bioeconomy, the production of polyhydroxyalkanoates (PHAs) using renewable biomass has acquired more attention. However, expensive biomass pretreatment and low yield of PHAs pose significant disadvantages in its large-scale production. To overcome such limitations, the most recent advances in metabolic engineering strategies used to develop high-performance strains that are leading to a new manufacturing concept converting biomass to PHAs with co-products such as amino acids, proteins, biohydrogen, biosurfactants, and various fine chemicals are critically summarized. This review article presents a comprehensive roadmap that highlights the integrated biorefinery strategies, lifecycle analysis, and techno-economic assessment for sustainable and economic PHAs production. Finally, current and future challenges that must be addressed to transfer this technology to real-world applications are reviewed.     

新型生物材料多聚羟基烷酸的开发与应用

综述了新型生物材料多聚羟基烷酸开发研究的历史与现状，重点介绍了多聚羟基烷酸生产和应用中取得的成果与存在的问题，并展望了这一新材料的发展趋势与应用前景。     

Extraction and purification of Polyhydroxyalkanoates (PHAs): application of Thermoseparating aqueous two-phase extraction

Being biodegradable, non-toxic and renewable as well as having similar or better properties than commercial plastics, polyhydroxyalkanoates (PHAs) can be a potential game changer in the polymer industry. Although viewed as a sustainable alternative to petrochemicals due to its biodegradability, PHAs are plagued with low commercial value due to their high production and recovery costs. Having the benefits of providing a mild environment for bioseparation, being environment-friendly and scalable, together with it its distinctive thermoseparating properties and ease of recyclability, thermoseparating-based aqueous two-phase extraction (ATPE) has provided the eco-friendly and economical solution to the PHA dilemma. ATPE-influencing factors such as types of thermoseparating polymer, concentration of phase-forming components, pH, and effect of centrifugation were investigated. Under the condition of 14 wt/wt% of EOPO 3900 concentration, 14 wt/wt% of ammonium sulfate concentration and pH 6 without the needs for extra centrifugation steps, a recovery yield and a purification factor of up to 72.2% and 1.61 fold can be achieved with the copolymers which can be recycled and reused twice. Thermoseparating ATPE has thus been proven to be a powerful primary purification tool for PHAs.