木质素生物合成可降解包装材料聚羟基脂肪酸酯的研究进展

目的 通过对木质素生物合成聚羟基脂肪酸酯(PHAs)的研究,实现PHAs的低成本、规模化生产和木质素的高值化利用。方法 归纳分析现阶段国内外木质素降解菌及生物合成PHAs的主要菌种和目前存在的问题,介绍生物合成PHAs的木质素底物种类、合成过程中工艺优化策略的相关研究进展,同时总结PHAs在包装领域的相关应用。结果 木质素生物合成PHAs过程中,通过筛选木质素降解菌、培养PHAs合成菌、优化PHAs的合成工艺及影响因素,可有效提高木质素底物的转化率和PHAs的产量,从而降低生产成本。结论 木质素转化为PHAs的过程虽然面临着一些挑战,但随着技术的不断创新和生产工艺的优化,木质素为底物合成的绿色生物塑料PHAs在包装领域会有广阔的应用前景和发展空间,必将推动包装材料向绿色化、安全化方面发展。     

生物可降解塑料——聚羟基脂肪酸酯（PHA）的生产技术研究

清华大学和中国科学院微生物研究所合作超额完成了可生物降解塑料专题的攻关任务,该专题包括用废糖蜜为原料生产可生物降解塑料聚羟基丁酸酯(PHB)、基因工程菌生产可生物降解塑料PHB、用水解淀粉为原料生产可生物降解塑料PHB及其共聚物PH-BV、可生物降解塑料PHB的改性和应用研究等4个子专题。并在此基础上实现了世界上首次规模化生产第三代PHA——羟基丁酸共聚羟基己酸酯(PHBHHx),为我国的生物可降解塑料工业化研究开辟了广阔的前景。     

New challenges for syngas fermentation: towards production of biopolymers

Organic wastes are a suitable feedstock for the production of value‐added products that have been insufficiently exploited due to their complexity, which challenges their transformation by conventional procedures. Gasification and pyrolysis of organic wastes can reduce this complexity by producing syngas (CO plus H₂ and other C1 gases), which can be used as a valuable commodity by catalytic conversion into chemicals. However, the high cost and susceptibility to poisoning of chemical catalysts have encouraged research on biocatalysts that convert C1 components of syngas into different multi‐carbon compounds. Nowadays, research on syngas fermentation is receiving much attention in order to enhance the productivity of microorganisms by remodeling their metabolism and by optimizing the bioreactor operational conditions. This review highlights the new technical achievements of pyrolysis as well as the new biotechnological uses of syngas for the production of bulk chemicals and biopolymers, discussing the major bottlenecks that challenge syngas fermentation. © 2015 Society of Chemical Industry     

微生物聚羟基脂肪酸酯的应用新进展

生物制造产业系包括生物燃料、生物材料和生物化学品的产业,近来也称为“白色生物技术”。由于国内外对有关不依赖于石油原料、环保以及二氧化碳减排和可再生资源的利用等产业的重视,生物制造产业得到了快速发展的机会。聚羟基脂肪酸酯（简称PHA）拥有优良的生物可降解性、生物相容性和光学性能,是当今生物制造的重点之一。经过数十年的努力,PHA已经成长为一个包括工业发酵、环保材料、生物燃料和医用植人材料等的产业链。综述了聚羟基脂肪酸酯的应用新进展及国内发展现状。     

动胶菌发酵生产聚羟基烷酸的动力学模型

引言 聚羟基烷酸(PHAs)是许多细菌细胞内积累的一种碳源和能源贮藏物质[1-2],仅由C、H和O元素组成[3],是一类可完全生物降解、具有良好加工性能和广阔应用前景的新型热塑性材料[4-6].为实现PHAs发酵的优化控制,必须对发酵过程的菌体生长和产物形成的动力学有充分的研究和了解,以降低生产成本,为最终实现工业化生产打下基础.因此,动力学模型的建立,对优化控制发酵条件,实现规模生产是必不可少的.目前,国内外的研究主要集中利用Wautersia eutropha及工程菌株生产PHAs,关于以Wautersia eutropha生产PHB的发酵动力学模型报道很多[7-9],但是由于Wautersia eutropha产PHAs的培养条件较为严格,对微量元素和碳氮源浓度都有要求[9],故此生产成本较高.     

Composite scaffolds for cartilage tissue engineering based on natural polymers of bacterial origin,thermoplastic poly(3‐hydroxybutyrate) and micro‐fibrillated bacterial cellulose

Cartilage tissue engineering is an emerging therapeutic strategy that aims to regenerate damaged cartilage caused by disease, trauma, ageing or developmental disorder. Since cartilage lacks regenerative capabilities, it is essential to develop approaches that deliver the appropriate cells, biomaterials and signalling factors to the defect site. Materials and fabrication technologies are therefore critically important for cartilage tissue engineering in designing temporary, artificial extracellular matrices (scaffolds), which support 3D cartilage formation. Hence, this work aimed to investigate the use of poly(3‐hydroxybutyrate)/microfibrillated bacterial cellulose (P(3HB)/MFC) composites as 3D‐scaffolds for potential application in cartilage tissue engineering. The compression moulding/particulate leaching technique employed in the study resulted in good dispersion and a strong adhesion between the MFC and the P(3HB) matrix. Furthermore, the composite scaffold produced displayed better mechanical properties than the neat P(3HB) scaffold. On addition of 10, 20, 30 and 40 wt% MFC to the P(3HB) matrix, the compressive modulus was found to have increased by 35%, 37%, 64% and 124%, while the compression yield strength increased by 95%, 97%, 98% and 102% respectively with respect to neat P(3HB). Both cell attachment and proliferation were found to be optimal on the polymer‐based 3D composite scaffolds produced, indicating a non‐toxic and highly compatible surface for the adhesion and proliferation of mouse chondrogenic ATDC5 cells. The large pores sizes (60 ‐ 83 µm) in the 3D scaffold allowed infiltration and migration of ATDC5 cells deep into the porous network of the scaffold material. Overall this work confirmed the potential of P(3HB)/MFC composites as novel materials in cartilage tissue engineering. © 2016 Society of Chemical Industry     

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     

Modification of poly(3‐hydroxybutyrate)‐co‐poly(3‐hydroxyvalerate) with natural rubber

Composites of poly(3‐hydroxybutyrate)‐co‐poly(3‐hydroxyvalerate) (PHBHV) with 6% of 3‐hydroxyvalerate (HV) and natural rubber (NR) were prepared by a solvent‐casting method. Different approaches were tested for the composite preparation. Both PHBHV and NR were dissolved in chloroform, followed by its evaporation, giving various layers. The mechanical properties and morphology of the obtained composites were evaluated by tensile tests and scanning electron microscopy (SEM), respectively. The obtained results demonstrated that the final composite has excellent mechanical properties when compared with PHBHV. SEM analysis unequivocally showed the excellent adhesion between the two polymeric layers. This new material was also tested as a drug delivering system using flurbiprofen as a model drug, and then the diffusion coefficients were determined. This article describes an easy method to produce a desirable composite from PHBHV and NR. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

微生物聚羟基脂肪酸酯的应用新进展

生物制造产业系包括生物燃料、生物材料和生物化学品的产业,近来也称为"白色生物技术"。由于国内外对有关不依赖于石油原料、环保以及二氧化碳减排和可再生资源的利用等产业的重视,生物制造产业得到了快速发展的机会。聚羟基脂肪酸酯(简称PHA)拥有优良的生物可降解性、生物相容性和光学性能,是当今生物制造的重点之一。经过数十年的努力,PHA已经成长为一个包括工业发酵、环保材料、生物燃料和医用植入材料等的产业链。综述了聚羟基脂肪酸酯的应用新进展及国内发展现状。