细菌纤维素生产与应用研究进展

简要介绍了细菌纤维素菌种选育、发酵条件优化,以及细菌纤维素在食品、医药、高级音响设备振动膜、造纸与无纺织物等方面应用研究的近况。由于细菌纤维素可形成纳米级的极细纤维,具有极高的杨氏模量和机械强度,以及高纯度和高结晶度、高亲水性和生物可降解性等特点,预计不久将成为一种多用途的商品。     

细菌纤维素的研究进展

细菌纤维素是由醋酸杆菌属、根瘤菌属、土壤杆菌属、八叠球菌属等的某些细菌在一定条件下产生的,其中最有代表性的细菌是木醋杆菌。与传统植物纤维素相比,细菌纤维素具有很高的化学纯度。主要介绍细菌纤维素性质、生物合成的方法及其在食品工业、造纸工业和作为一种生物材料在医学工程等方面的应用。     

细菌纤维素研究新进展

综述细菌纤维素的结构和性质、生物合成和分泌的过程与调控以及影响合成的因素。细菌纤维素的化学构成与天然纤维素相近 ,但又有其特殊性。参与纤维素合成的酶有 8种 ,其中纤维素合成酶是合成纤维素的关键酶和特征酶 ,环二鸟苷酸系统是研究得比较透彻的纤维素合成调节系统。培养基组成、发酵工艺和设备都会影响细菌纤维素的产量。深入研究细菌纤维素的合成和调节机制有助于揭示植物纤维素的生物合成机理和促进细菌纤维素的大规模商业化应用。     

细菌纤维素性质及应用的研究进展

细菌纤维素是由微生物合成的多孔性网状纳米级生物高分子材料,由于它具备高持水性、高透气性、良好生物相容性、高机械强度、三维网络结构等独特性质,因此在纺织、医用敷料、组织工程、食品、导电材料等行业具有广阔的应用前景。本文主要从性质和应用两方面对其近年来的研究进展做了综述,并对未来的发展做了展望。     

源于葡糖杆菌属细菌纤维素材料的检测分析

利用自筛的葡糖杆菌属菌株AXB(X),发酵获得产物细菌纤维素(BC),通过傅立叶红外光谱、X-射线衍射以及扫描电子显微镜等仪器研究其材料特性,确认BC是高纯度的纤维素,且晶型属于纤维素I型;通过酶解和酸解试验显示该产物纯度达95%以上,持水率在95%以上。此外,扫描电镜观察其产物表面形态结构表明纤维相互交织成具有超细精密多孔的网络结构,且具有比滤纸、棉纤维和桑皮纤维更高的结晶度。     

细菌纤维素在生物医学材料中应用的研究进展

细菌纤维素是一种天然的生物高聚物,具有生物活性、生物可降解性、生物适应性,具有独特的物理、化学和机械性能,例如高的结晶度、高的持水性、超细纳米纤维网络、高抗张强度和弹性模量等,因而成为近来国际上新型生物医学材料的研究热点。本文概括了细菌纤维素的性质、研究历史以及在生物医学材料上的应用,重点阐述了细菌纤维素在组织工程支架、人工血管、人工皮肤和治疗皮肤损伤方面的应用以及当前研究现状。     

细菌纤维素的研究进展

细菌纤维素是一种新型微生物合成材料,在食品、医药、纺织、化工等方面有着巨大的应用潜力。简要介绍了细菌纤维素的性质和结构特点,系统阐述了细菌纤维素的生物合成途径及影响细菌纤维素产量的因素。     

醋酸杆菌发酵生产细菌纤维素的研究进展

简要介绍醋酸杆菌发酵生产纤维素研究进展,内容包括：产纤维素的微生物、醋酸菌纤维素的结构特点、生物合成途径、一般提取处理及分析测定方法、商业用途、工业化发酵生产醋酸菌纤维素过程中存在的主要问题及发展前景。     

细菌纤维素的合成与调控进展

细菌纤维素是1种天然的高纯度生物多聚物,与木质纤维素相比,其生产和加工过程更为方便和环保,因此已成为1种极有潜力的生物材料。葡糖酸醋杆菌是目前已知的产纤维素能力最高的菌株。综述了葡糖酸醋杆菌的细菌纤维素合成和调控机制以及为提高产量所进行的基因工程手段和培养方法。     

Formation, derivatization and applications of bacterial cellulose

Acetobacter xylinum produces highly crystalline cellulose extracellulary using glucose as a carbon source. The polymer formed is free of other biogenic compounds, separable in a simple way and characterized by its high water-absorption capacity. Stepwise solvent exchange from water to unpolar solvents leads to a drastic decrease of the water content of the bacterial cellulose without decrease of the highly swollen and activated state. Heterogeneous as well as homogeneous derivatizations, e.g. carboxymethylation, silylation and acetylation, were performed on the wet or dried biopolymer. Furthermore, different methods for formation of hollow fibres during biosynthesis were investigated. Such tubes may have applications as biocompatible material in medicine.     

Recent developments in the production and applications of bacterial cellulose fibers and nanocrystals

Cellulosic nanomaterials provide a novel and sustainable platform for the production of high performance materials enabled by nanotechnology. Bacterial cellulose (BC) is a highly crystalline material and contains pure cellulose without lignin and hemicellulose. BC offers an opportunity to provide control of the products’ properties in-situ, via specific BC production methods and culture conditions. The BC potential in advanced material applications are hindered by a limited knowledge of optimal BC production conditions, efficient process scale-up, separation methods, and purification methods. There is a growing body of work on the production of bacterial cellulose nanocrystals (BCNs) from BC fibers. However, there is limited information regarding the effect of BC fibers’ characteristics on the production of nanocrystals. This review describes developments in BC and BCNs production methods and factors affecting their yield and physical characteristics.     

Properties and applications of undecylprodigiosin and other bacterial prodigiosins

The growing demand to fulfill the needs of present-day medicine in terms of novel effective molecules has lead to reexamining some of the old and known bacterial secondary metabolites. Bacterial prodigiosins (prodiginines) have a long history of being re markable multipurpose compounds, best examined for their anticancer and antimalarial activities. Production of prodigiosin in the most common producer strain Serratia marcescens has been described in great detail. However, few reports have discussed the ecophysiological roles of these molecules in the producing strains, as well as their antibiotic and UV-protective properties. This review describes recent advances in the production process, biosynthesis, properties, and applications of bacterial prodigiosins. Special emphasis is put on undecylprodigiosin which has generally been a less studied member of the prodigiosin family. In addition, it has been suggested that proteins involved in undecylprodigiosin synthesis, RedG and RedH, could be a useful addition to the biocatalytic toolbox being able to mediate regio- and stereoselective oxidative cyclization. Judging by the number of recent references (216 for the 2007–2013 period), it has become clear that undecylprodigiosin and other bacterial prodigiosins still hold surprises in terms of valuable properties and applicative potential to medical and other industrial fields and that they still deserve continuing research curiosity.     

Increased production of bacterial cellulose as starting point for scaled-up applications

Bacterial cellulose is composed of an ultrafine nanofiber network and well-ordered structure; therefore, it offers several advantages when used as native polymer or in composite systems.

In this study, a pool of 34 acetic acid bacteria strains belonging to Komagataeibacter xylinus were screened for their ability to produce bacterial cellulose. Bacterial cellulose layers of different thickness were observed for all the culture strains. A high-producing strain, which secreted more than 23 g/L of bacterial cellulose on the isolation broth during 10 days of static cultivation, was selected and tested in optimized culture conditions. In static conditions, the increase of cellulose yield and the reduction of by-products such as gluconic acid were observed. Dried bacterial cellulose obtained in the optimized broth was characterized to determine its microstructural, thermal, and mechanical properties. All the findings of this study support the use of bacterial cellulose produced by the selected strain for biomedical and food applications.

     

Properties and potential applications of natural cellulose fibers from the bark of cotton stalks

Natural cellulose fibers have been obtained from the bark of cotton stalks and the fibers have been used to develop composites. Cotton stalks are rich in cellulose and account for up to 3 times the quantity of cotton fiber produced per acre. Currently, cotton stalks have limited use and are mostly burned on the ground. Natural cellulose fibers obtained from cotton stalks are composed of approximately 79% cellulose and 13.7% lignin. The fibers have breaking tenacity of 2.9 g per denier and breaking elongation of 3% and modulus of 144 g per denier, between that of cotton and linen. Polypropylene composites reinforced with cotton stalk fibers have flexural, tensile and impact resistance properties similar to jute fiber reinforced polypropylene composites. Utilizing cotton stalks as a source for natural cellulose fibers provides an opportunity to increase the income from cotton crops and make cotton crops more competitive to the biofuel crops.     

Preparation of cellulose films from solution of bacterial cellulose in NMMO

Bacterial cellulose (BC) was dissolved in N-methylmorpholine N-oxide (NMMO) to prepare regenerated BC films (RBC) with phase inversion. The solubility of BC, supermolecule on structure, morphology, thermal and physical properties of the films were investigated by Fourier transform infrared spectroscopy (FT-IR), solid-state cross polarization/magic angle spinning ¹³C nuclear magnetic resonance (CP/MAS ¹³C NMR), wide-angle X-ray diffraction (WAXD), scanning electron microscope (SEM), and thermogravimetric analysis (TGA). The investigation suggested BC was dissolved completely in NMMO. From the C₆ signal shifts to the amorphous area, the crystallinity of materials decreased from 79.20% to 38.17%, and the transformation from cellulose I to II occurred. It was also found that the banded structure of the native materials was replaced by homogeneous and densified sections, so RBC films had better mechanical and barrier properties, and do thermal stability was similar to that of the native BC.