大豆渣制备细菌纤维素的研究

细菌纤维素(BC)是一类由微生物产生的纳米纤维素,其偏高的生产成本,尤其是成本相对较高的发酵碳源,限制了其工业化生产和应用。以廉价丰富的大豆渣为原料,进行稀酸预处理,剩余的不溶性滤渣经纤维素酶的水解获得可发酵糖。分别以酸预处理液和酶水解液配制培养基,用来制备细菌纤维素。结果表明:以酶解液作为发酵碳源的BC产量明显高于以酸预处理液为碳源时的产量;且以Ca(OH)2处理的酶解液为碳源时,BC产量可达5.52 g/L,远高于葡萄糖对照组(7.4倍),表明大豆渣作为碳源生产BC具有良好的应用前景和商业价值。     

红茶菌制备细菌纤维素的研究

寻找高效的生产菌和发酵工艺以及廉价高效的培养基是解决当前细菌纤维素产业化面临的高生产成本和低产率等瓶颈问题的重要手段。以红茶菌和木葡糖酸醋杆菌作为生产菌株,比较研究了不同碳源、氮源以及茶叶浓度对两种菌合成细菌纤维素的影响。结果表明,以红茶菌制备的细菌纤维素与木葡糖酸醋杆菌无本质区别;红茶菌生产细菌纤维素的效率显著高于木葡糖酸醋杆菌,产量可提高3倍以上。     

稻草秸秆综纤维素糖化液发酵产头孢菌素C的研究

目前头孢菌素C等抗生素的发酵碳源主要是源自玉米、小麦和甘薯等的工业淀粉,存在着"与人争粮"的危机,而利用资源丰富的木质纤维素类生物质资源作为替代碳源,是应对这一危机的有益尝试。利用稻草综纤维素糖化液作为速效碳源,综纤维素-纤维素酶体系作为持续碳源,在综纤维素含量为40g/L、纤维素酶量为0.4%、硫酸铵10g/L、玉米浆添加量为60g/L以及初始pH为6.0时,顶头孢霉(Cephalosporium acremonium)CPCC 400039发酵产CPC效价最高,为382.12U/mL,为标准培养基最佳效价的84.04%。研究结果进一步证实,经SO_3微热爆预处理的稻草秸秆,在纤维素酶的水解糖化作用下所得的糖化液,不仅葡萄糖含量高而且糠醛、乙酸等发酵抑制物含量低,完全可以应用于头孢菌素C等抗生素乃至工业生物发酵中,作为原料丰富且廉价的碳源替代物。     

黄酒糟发酵制备细菌纤维素的技术研究

以黄酒糟酶解液为主要原料,葡糖醋杆菌BC19-2发酵制备细菌纤维素。分别考察了温度、pH、接菌量、酒糟的酶解时间等因子对黄酒糟发酵生产细菌纤维素的影响,可视化表征细菌纤维素制备的微观过程。结果表明,单因素比较优化的最佳发酵条件是酒糟酶解3小时、初始pH6.0、接种量为6%时,在30℃恒温发酵7天,细菌纤维素的产量即达70 g/100 mL(湿重),干重约3.8 g/100 mL。扫描电镜表征生产过程发现:菌株初始发酵时产生短绒状纤维成纳米薄膜覆盖于培养基表面,随后菌体依附薄膜产生大量细丝长条状柔软的长纤维,后期菌株产生结晶度更高的纤维素,附着于纤维膜表面,结束发酵。黄酒酒糟资源丰富,成本低廉,酶解后发酵生产纳米细菌纤维素产率高,性能优异,具有良好的工业化应用前景。     

一株细菌纤维素生产菌株Gluconacetobacter xylinus的分离鉴定及其产物分析CSCD

为获得具有机械强度及弹性模量高等优点的细菌纤维素,满足其在食品工业、生物医学、造纸、声学器材和石油开采等方面的广泛应用。本研究通过初步活化和分步富集的方法获得细菌纤维素生产菌株,经过16S rDNA及形态学鉴定后,利用单因子试验对该菌株的发酵条件进行了优化,并利用扫描电子显微镜、红外光谱分析以及X-衍射等技术对获得的细菌纤维素进行表征。最终筛选获得一株细菌纤维素生产菌株,经鉴定为木葡糖酸醋杆菌Gluconacetobacter xylinus,命名为G.xylinus 5-2;经碳源、氮源、pH及其他影响因素的优化,该菌株发酵生产的细菌纤维素纯化干燥后干重达到13.2 g/L;发酵分离产物经扫描电子显微镜、红外光谱分析以及X-衍射等表征分析,证明该产物为细菌纤维素;对细菌纤维素进行力学性质表征分析,表明该细菌纤维素的弹性模量达到3.38 GPa。因此,本研究筛选获得了一株在生产效率和产品性能等方面都较为优异的纤维素生产菌株G.xylinus 5-2,并对其细菌纤维素的发酵条件进行了初步分析,为工业化生产高性能细菌纤维素奠定了基础。     

利用糖蜜制备细菌纤维素的研究

细菌纤维素（BC）是一类由微生物产生的纤维素。细菌纤维素以其独特的物理和化学性质被广泛应用于医药、食品、造纸、纺织等领域。然而，BC应用的最大挑战是其生产成本，尤其是发酵生产碳源的成本相对较高。以相对廉价的糖蜜为原料，研究比较了不同预处理方法（硫酸-热处理、热处理和未处理）以及生产菌种（木葡糖醋杆菌和红茶菌）对细菌纤维素产量的影响。结果表明，硫酸-热处理之后的糖蜜获得的细菌纤维素产量最高，可达6．0g/L，比用葡萄糖制备细菌纤维素的产量提高了78％。当以红茶菌为菌种，细菌纤维素的产量可达12．0g/L，是木葡糖醋杆菌作为菌种的两倍。与葡萄糖和果糖相比，糖蜜制备的细菌纤维素同样具有三维网状结构，但是含水率较低，杨氏模量较小。     

细菌纤维素的合成原料多样性及其合成机制研究概况

概述了细菌纤维素合成原料的多样性、细菌纤维素的合成途径及其调控机制。综述了用于生产细菌纤维素的三种原材料及其研究现状,商业化碳源价格昂贵、大规模合成应优先考虑低廉的农副产品和工业副产物。阐述了细菌纤维素的合成是有多种相关酶参与的调控过程,主要包括糖的水解和转化,纤维素的合成以及最后的组装和分泌三个步骤。指出用低廉碳源物质作为原材料存在的问题及解决思路,并对细菌纤维素的大规模生产及开发应用进行了展望。     

杨木屑酶解液作为碳源制备细菌纤维素的条件优化

目的:提高木屑酶解液作为碳源制备细菌纤维素的能力。方法:采用单因素法,对木醋杆菌合成细菌纤维的培养基成分和发酵条件进行了优化。结论:最终确定了葡萄糖15g/L,杨木屑酶解液75(ml/L),蛋白胨7.5g,酵母粉7.5g,无水磷酸氢二钠2.2g,柠檬酸一水化合物1.2g,pH5.5,发酵温度30℃,发酵时间5d的发酵条件,其产量较优化前调高了近1倍。     

中国塑料专利

一种氧化石墨烯/细菌纤维素抗菌复合材料的制备方法其特征在于包括以下操作步骤:1)将活化后的细菌纤维素生产菌接入种子培养基培养,再按照5%~10%的接种量接入发酵培养基中,充分混合均匀后,放置在(30±2)℃恒温培养箱中,静置发酵1~2周,获得细菌纤维素湿膜;2)将细菌纤维素湿膜碱洗后通过机械方法打浆成均相悬浮液;3)将氧化石墨烯溶液与细菌纤维素均相悬浮液混合,超声分散后制成均相混合液;4)将均相混合液减压过滤,冷冻干燥后     

细菌纤维素的制备和应用研究进展

细菌纤维素（Bacterial cellulose,简称BC）又称微生物纤维素,具有独特超细网状纤维结构、不含木质素和其他细胞壁成份,吸水性强、高生物兼容性、可降解性等优良特点,日益成为人们关注的焦点.综述了近年来国内外在细菌纤维素的菌种筛选、碳源优化、发酵工艺方面的研究成果,以及细菌纤维素在肾透析膜、血管支架、皮肤代用品、化妆品膜、减肥代餐食品等方面的应用.     

Wheat straw acid hydrolysate as a potential cost‐effective feedstock for production of bacterial cellulose

BACKGROUND: Bacterial cellulose (BC) is an extracellular biopolymer product of vinegar bacteria, which is widely used in many areas. However, problems of high production cost have prevented widescale extension of BC applications. In this work, BC was produced using wheat straw hydrolysates prepared by dilute acid hydrolysis instead of the usual carbon sources, with the aim of decreasing the production costs of BC. RESULTS: In order to remove microbial growth inhibitors, wheat straw hydrolysates were detoxified by treatment with various alkalis including calcium hydroxide, sodium hydroxide and ammonia, and their combination with activated charcoal or laccase. Results showed that the detoxification effect using calcium hydroxide was much better than that with the other alkalis. The BC yield using hydrolysate treated with Ca(OH)₂ and activated charcoal was at least 50% higher than that using routine carbon sources. Additionally, the ions of Ca²⁺ and Na⁺ in the hydrolysates had important and positive effects on BC production while Cl^? exhibited negative effects. CONCLUSION: Wheat straw was shown to be a suitable feedstock for BC production, and a process was established for BC production from lignocellulosic feedstocks using a detoxification treatment. Copyright © 2011 Society of Chemical Industry     

Bacterial Cellulose Production from Industrial Waste and by-Product Streams

The utilization of fermentation media derived from waste and by-product streams from biodiesel and confectionery industries could lead to highly efficient production of bacterial cellulose. Batch fermentations with the bacterial strain Komagataeibacter sucrofermentans DSM (Deutsche Sammlung von Mikroorganismen) 15973 were initially carried out in synthetic media using commercial sugars and crude glycerol. The highest bacterial cellulose concentration was achieved when crude glycerol (3.2 g/L) and commercial sucrose (4.9 g/L) were used. The combination of crude glycerol and sunflower meal hydrolysates as the sole fermentation media resulted in bacterial cellulose production of 13.3 g/L. Similar results (13 g/L) were obtained when flour-rich hydrolysates produced from confectionery industry waste streams were used. The properties of bacterial celluloses developed when different fermentation media were used showed water holding capacities of 102–138 g·water/g·dry bacterial cellulose, viscosities of 4.7–9.3 dL/g, degree of polymerization of 1889.1–2672.8, stress at break of 72.3–139.5 MPa and Young’s modulus of 0.97–1.64 GPa. This study demonstrated that by-product streams from the biodiesel industry and waste streams from confectionery industries could be used as the sole sources of nutrients for the production of bacterial cellulose with similar properties as those produced with commercial sources of nutrients.     

燃料乙醇生产技术路线分析及产业发展建议

对化学合成乙醇路线(合成气催化制乙醇、乙酸加氢制乙醇工艺)和生物发酵制乙醇路线(粮食发酵、非粮原料发酵、合成气发酵工艺)及其技术特点进行了分析,重点阐述了纤维素乙醇生产工艺、核心技术及国内外开发现状,并对我国燃料乙醇产业发展提出了有关建议.     

Comparison of bacterial cellulose production by Gluconacetobacter xylinus on bagasse acid and enzymatic hydrolysates

To fulfill the comprehensive utilization of cellulose and hemicellulose components in bagasse for bacterial cellulose (BC) production, both bagasse acid and enzymatic hydrolysates were used for BC production by Gluconacetobacter xylinus. Although the BC accumulation rate was slower during the early period of fermentation in the bagasse acid hydrolysate than in the enzymatic hydrolysate, the highest BC yield (1.09 vs. 0.42 g/L) was higher in the bagasse acid hydrolysate. The substrate utilization was evaluated in both bagasse acid and enzymatic hydrolysates, and glucose, xylose, and acetic acid were better carbon sources than arabinose and cellobiose for G. xylinus. The structure of the BC samples obtained from bagasse acid and enzymatic hydrolysates, including the microscopic morphology, functional groups, and crystals, was similar especially in the later phase of fermentation, which was analyzed by field emission scanning electron microscopy, Fourier transform infrared spectroscopy, and X‐ray diffraction. Thus, both bagasse acid and enzymatic hydrolysates could be promising substrates for BC production. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45066.     

小径纳米纤维素管的生物制备及其表征

以透氧硅胶双套管为模具,设计组装了一套新型生物反应装置,利用红茶菌和套管法生产细菌纤维素（BC）小径人工血管材料。研究发现,细菌纤维素可以分别在内外两根硅胶管的外表面和内表面同时生成,并最终长到一起形成整体BC管。获得的BC管不仅具有较好的强度和光滑平整的内外表面,而且纳米纤维交织紧密,无纤维分层现象,具有突出优点和应用潜力。该制备方法简便易行,成本低廉,生产效率高,可工业化生产。     

Physicochemical properties of bacterial cellulose obtained from different Kombucha fermentation conditions

The production of bacterial cellulose has been limited due to its high cost and low productivity. Alternative low-cost sources of this biopolymer of high purity and biocompatibility are needed in order to benefit from its enormous potential. Kombucha tea is a trend functional beverage whose production is growing exponentially worldwide, and the bacteria present in this fermented beverage belonging to the genus Komagataeibacter are capable of producing a crystalline biofilm with interesting properties. Obtaining bacterial cellulose from Kombucha tea has already been studied, however several fermentation conditions are being optimized in order to scale-up its production. In this study, we characterized the bacterial cellulose produced from three different Kombucha fermentation conditions. The scanning electron microscopy images revealed the crystalline structure of the biofilms. The energy-dispersive x-ray analysis exhibited the chemical composition of the crystals. The thermogravimetric analysis showed a rate of degradation between 490 and 560°C and the differential scanning calorimetry confirmed the presence of crystalline and amorphous regions in the bacterial cellulose samples. The results suggested that crystalline cellulose could be obtained by varying the fermentation conditions of Kombucha tea.     

Bioethanol production from biomass: carbohydrate vs syngas fermentation

Environmental problems associated with the use of fossil fuels as well as their expected scarcity in the near future requires a search for new alternative fuels produced from renewable sources. Bioethanol is a biofuel that can be obtained from biomass and waste as feedstocks through fermentation. Two major routes allow conversion of the feedstocks to fermentable substrates, i.e. the hydrolytic route and the thermochemical route. In the hydrolytic route, the feedstock undergoes a pretreatment stage first, aimed at facilitating the subsequent hydrolytic treatment. Chemical, physical or biological pretreatments can be applied. Lignocellulosic feedstocks are mainly composed of cellulose, hemicellulose and lignin. The pretreatment attacks the lignin and hemicellulose polymers and makes cellulose more accessible in the next, hydrolytic, stage. The hydrolytic treatment uses enzymes to convert the cellulose polymer to simple, fermentable, sugars, mainly glucose. Simple sugars obtained from hemicellulose and cellulose are then fermented by yeasts to bioethanol. In the thermochemical alternative, the feedstock is gasified, yielding syngas – a mixture largely composed of CO, CO₂ and H₂ – which can be fermented anaerobically, usually by clostridia, to ethanol or other products. In both cases, downstream processes are then applied to recover and purify the biofuel. The different stages involved in both alternatives are described, and both processes are compared in terms of their main characteristics and development stage. © 2015 Society of Chemical Industry     

Enzymatic saccharification of dissolution pretreated waste cellulosic fabrics for bacterial cellulose production by Gluconacetobacter xylinus

BACKGROUND: Waste textiles, such as dyed cellulosic and/or polyester blended fabrics have the potential to serve as an alternative feedstock for the production of biological products via microbial fermentation. Dissolution pretreatment was employed to enhance the enzymatic saccharification of dyed and synthetic fiber blended cellulosic fabrics. The fermentable reducing sugars obtained from waste cellulosic fabrics were used to culture Gluconobacter xylinus for value‐added bacterial cellulose (BC) production. RESULTS: Concentrated phosphoric acid was the ultimate cellulose solvent for dissolution pretreatment since 5% w/w cellulosic fabric can be completed dissolved at 50 °C. After regeneration in water, the cellulosic precipitate was subjected to cellulase hydrolysis, resulting in at least 4‐fold enhancement of saccharification rate and reducing sugars yield. The colored saccharification products can be utilized by G. xylinus to produce BC, approximately 1.8 g L^?1 BC pellicle was obtained after 7 days static cultivation. CONCLUSION: Dyed and blended waste fabric can be pretreated effectively by dissolution to produce fermentable sugars by cellulase hydrolysis. Dissolution pretreatment can expose the dyed or polyester fiber covered digestible cellulosic fibers to cellulase and leads to a significant enhancement of saccharification yield. The colored saccharification products have no significant inhibiting effect on the fermentation activity of G. xylinus for BC production. Copyright © 2010 Society of Chemical Industry