产纤维素酶放线菌的筛选鉴定及其对玉米秸秆的降解

从寒地黑土中筛选得到一株对纤维素具有降解能力的菌株,观察该菌株的形态特征并对其进行分子生物学鉴定。采用响应曲面法对该菌株降解玉米秸秆的条件进行优化,并对玉米秸秆降解前后的结构变化、主要成分变化进行观察和测定。结果表明:该菌编号为GS-4-21,其透明圈与菌落直径的比值(D/d)为5.54±0.20,滤纸酶活、纤维素外切酶活、纤维素内切酶活和β-糖苷酶酶活分别为11.94±0.51、12.07±0.43、32.94±0.83和30.87±1.04 U/mL。经鉴定菌株GS-4-21属于链霉菌属。当以体积分数3%接种至pH为6的发酵培养基中,28℃、160 r/min发酵5 d时,玉米秸秆的降解率可达23.54%。SEM结果表明:菌株GS-4-21具有较好的纤维素降解能力。玉米秸秆中纤维素、半纤维素、木质素的降解率分别为30.33%、31.95%、18.91%。     

耐高温秸秆降解菌的筛选、鉴定及复合菌剂降解效果分析

[目的]筛选耐高温秸秆降解菌,并对其进行鉴定,分析复合菌剂的秸秆降解效果。[方法]从河南地区农田腐烂的玉米秆、麦秸秆、枯枝败叶中通过分离培养基分离出4株耐高温且具有纤维素降解能力的菌种,并对其进行16/18SrRNA鉴定,NGW11菌株为米曲霉菌,NGW12菌株为芽枝孢霉菌,NGW13菌株为枯草芽孢杆菌,NGW14菌株为苏云金芽孢杆菌,复合菌液降解菌种组合为3︰1︰4︰2。[结果]通过DNS法测定各菌株对不同秸秆的纤维素降解酶活,结果表明复合菌液对不同秸秆都有较好的降解效果。     

一株用于印染废水脱色菌产漆酶条件的优化

脱色菌—白腐真菌主要用于纤维素、木质素的降解,在稻草降解、产酶量等方面报导较多,但对于用脱色菌-白腐真菌用于印染废水脱色菌种培养基优化报导较少。文章从白腐真菌产漆酶条件入手,试求对其产漆酶条件进行优化。     

选择性降解木质素白腐菌筛选的研究

对国内外15种产漆酶的白腐菌进行初步筛选,从中获得7株产漆酶活性较高的菌株。经对木材降解能力的分析及在培养过程中所产各种酶酶活的测定,得到了2株产漆酶酶活高、降解木质素选择性优良的菌株,其中Flammulinavelutipes和My-1两菌株经14天液体培养,漆酶酶活高达214IU/mL和231IU/mL。杨木经其处理30天后木质素降解率达到22.67%和15.46%。     

纤维素降解菌的筛选、酶活及对稻草秸秆的降解研究

以滤纸条为唯一碳源培养基对富含纤维素的土样微生物进行富集培养,再用刚果红纤维素琼脂培养基筛选降解效果好的菌株,根据菌落形态及显微结构进行鉴定,并测定其发酵液的FPAase酶活和对稻草秸秆的降解情况。通过刚果红纤维素琼脂培养基筛选得到的最具纤维素分解能力的真菌经形态鉴定为冬克青霉(Penicillium donkii),该菌在含有羧甲基纤维素钠的液体培养基中28℃,180 r/min培养,在第8d酶活力达到最大为15.0 U/m L。接种菌株21d的稻草纤维素含量由接种前的30.30%减少至26.36%。青霉1-4为冬克青霉,对纤维素有一定的降解能力,可以加速对稻草秸秆中纤维素的降解。     

酸/碱预处理对两株木霉降解玉米秸秆效果的影响

研究了木霉菌(Trichoderma jw-1)、木霉菌(Trichoderma jw-2)及曲霉(Aspergillus xm.)在相同培养条件下,以纤维素为碳源产葡聚糖内切酶活力(CMC酶活)及滤纸酶活力(FPA酶活)的情况,并将其进行混合培养发酵,研究了不同菌系配比对CMC酶活及FPA酶活的影响。并以CMC酶活及FPA酶活作为指标,利用不同化学法处理玉米秸秆,对预处理条件进行了优化。结果表明:Trichoderma jw-1与Trichoderma jw-2组合产纤维素酶量最高,CMC酶活可达2.76 U/mL,FPA酶活可达1.52 U/mL;经10%NaOH预处理后,Trichoderma jw-1与Trichoderma jw-2的复合菌系降解秸秆效率最好,秸秆干粉失重率可达76.8%。     

好氧生物预处理时间对玉米秸秆水解酸化的影响

以玉米秸秆为原料,先经复合菌系进行好氧生物预处理,然后接种厌氧污泥进行厌氧发酵,考察了预处理时间对厌氧发酵的影响,并测定木质纤维素结构及含量变化、关键性酶活、微生物多样性和厌氧发酵酸化产量。研究结果表明：随着预处理时间的延长,玉米秸秆的结构逐渐被破坏,木质素过氧化物酶活性逐渐降低,木聚糖酶和纤维素酶活性逐渐升高,最高分别达0.879和0.025 7 U/mg。放线菌、芽孢杆菌和曲霉菌是秸秆好氧生物预处理中的优势菌群。玉米秸秆经好氧生物预处理2 d,厌氧发酵产酸效果最佳,乙醇和挥发性脂肪酸产量为249.3 mg/g,比未处理提高了46.73%;玉米秸秆经好氧生物预处理5 d,乙醇和挥发性脂肪酸产量为138.2 mg/g,比未处理降低了18.66%。过长的玉米秸秆好氧预处理时间会使玉米秸秆中半纤维素、纤维素过度降解,这是造成玉米秸秆厌氧发酵产酸量下降的主要原因。以能源化、资源化为目的的玉米秸秆厌氧发酵预处理时,利用复合菌系好氧生物处理作为其预处理方法,应严格控制预处理时间,避免因为纤维素、半纤维素过度降解导致的产品产率下降问题。     

预处理方法对玉米秸秆发酵产氢的影响及其机理分析

研究了不同预处理方法对玉米秸秆发酵产氢气的影响和秸秆降解产氢的机理。实验分别采用酸解(AP)、酸解耦合固态酶解(AEP)、高温蒸煮(HP)和高温蒸煮耦合固态酶解(HEP)的玉米秸秆进行发酵产氢,分析预处理后秸秆累积产氢量与可溶性糖含量的关系。在此基础上,通过秸秆化学组成成分分析、傅里叶变换红外光谱(FT-IR)和X-射线衍射分析,探讨了秸秆降解的机理。结果表明,秸秆的累积产氢量与可溶性糖含量基本正相关,秸秆糖化效率是影响秸秆累积产氢量的主要因素。四种预处理方法主要作用于秸秆半纤维素和纤维素的无定型区,预处理过程皆在不同程度上提高了秸秆的结晶度,并在极大程度上提高了玉米秸秆的累积产氢量。其中AEP方法预处理秸秆效果最好,累积产氢量达到了226.1 m L·(g·TS)-1。     

玉米秸秆稀酸蒸汽爆破协同作用机制研究

以玉米秸秆原料,进行蒸汽爆破处理,比较了水蒸气蒸爆、稀酸和稀酸蒸爆3种预处理方法,通过对3种预处理过程中米秸秆纤维组分变化、纤维素和半纤维素降解产物和玉米秸秆结构分析以及酶解试验,探讨稀酸蒸汽爆破的协同作用机制.结果表明,稀酸蒸爆协同作用包括稀酸的软化和蒸汽爆破的活化两种机制:一是通过稀酸脱除大部分的半纤维素破坏了半纤...     

高效协同酶解中性汽爆玉米秸秆的工艺优化

玉米秸秆是我国主要的农业废弃物之一,在木质纤维素乙醇领域具有广阔的应用前景。而玉米秸秆预处理和酶法糖化成本过高是目前工艺中的重点和难点之一。从4种纤维素降解酶制剂中优选出对中性汽爆玉米秸秆有最佳协同效果的木霉和黑曲霉纤维素酶制剂（6∶4体积比混合）。在此基础上,评估了木聚糖酶、β-葡萄糖苷酶、β-葡聚糖酶、漆酶、锰过氧化物酶等酶制剂,聚乙二醇-4000、吐温-80、牛血清白蛋白等非酶因子对糖化效率的影响,得到了一组高效协同降解汽爆玉米秸秆的复合酶体系,并获得了适宜的糖化工艺。结果表明,以每克中性汽爆预处理的玉米秸秆为底物,加入10FPU木霉/曲霉混合酶液,并添加1000IU的木聚糖酶和0.05 g PEG4000,于50℃/150 r·min^-1相似文献   

Recycling of waste FRP and corn straw in wood plastic composite

Waste fiber reinforced polymer (FRP) combined with corn straw fiber was recycled and incorporated in wood plastic composite (WPC). The synergistic enhancement effect of glass fiber and corn straw fiber was investigated. The results show that there was a good physical interlocking structure among glass fiber of waste FRP, corn straw fiber and poly(vinyl chloride) (PVC) in WPC, which led to the enhancement of mechanical properties of WPC. With 30 phr (parts per hundreds of resin) waste FRP, the tensile strength and flexural strength of WPC were improved to 24 and 66 MPa, increased by 31% and 23% with respect to starting WPC. This study reveals that waste FRP and corn straw fiber can be good alternative for wood fiber in the production of WPC. POLYM. COMPOS., 38:2140–2145, 2017. © 2015 Society of Plastics Engineers     

Optimisation of cellulose conversion into fungal cell mass

Chaetomium cellulolyticum was cultivated on Avicel and/or stream-and NH₃-pre-treated straw in a 20 litre stirred tank reactor with batch and/or fed-batch operation. The influence of the substrate concentration, the impeller speed and the fed-batch operation on cell productivity was investigated. Steam-pretreated straw can be better utilised by the fungus than NH₃-pretreated straw. The optimal conditions at which maximum cell productivity and/or maximum cell mass concentration can be attained were evaluated for stream-pretreated straw. At the beginning of the growth phase the oxygen consumption rate reaches a significant maximum. At this point the enzyme activity begins to increase. The investigations with Avicel indicate that the cell productivity could be significantly increased by fed-batch operation. A microprocessor-controlled fed batch process controlled by alkaline consumption is recommended.     

Direct ethanol production from rice straw by coculture with two high-performing fungi

To develop efficient and economical direct ethanol production from fine rice straw crashed mechanically, two high-performing fungi, which can secret hyperactive cellulases and/or ferment effectively various sugars, were selected from some strains belong to Mucor circinelloides preserved in our laboratory. The simultaneous saccharification and fermentation (SSF) by coculture with these fungi was investigated. The screening of high-performing fungi resulted in the selection of NBRC 4572 as an ethanol-producing fungus and NBRC 5398 as a cellulase-secreting fungus. The strain 4572 produced ethanol aerobically from glucose and xylose in high yields of 0.420 g/g at 36 h and 0.478 g/g at 60 h, respectively, but secreted fairly low cellulases. On the other hand, the strain 5398 also produced ethanol from glucose in yield of 0.340 g/g though it had a little growth in xylose culture. However, it secreted hyperactive cellulases that are essential for hydrolysis of rice straw in culture and the maximum activities of endo-β-glucanase and β-glucosidase were 2.11 U/L and 1.47 U/L, respectively. In SSF of rice straw by coculture with two fungi selected, the ethanol production reached 1.28 g/L after 96 h when the inoculation ratio of the strain 5398 to the strain 4572 was 9.     

生物降解聚酯/秸秆纤维全生物降解复合材料研究进展

介绍了玉米秸秆、水稻秸秆及小麦秸秆的利用现状，阐述了秸秆纤维的表面处理方法（物理处理法、化学处理法及其他处理法），综述了生物降解聚酯/秸秆纤维全生物降解复合材料的主要品种及性能，最后对生物降解聚酯/秸秆纤维全生物降解复合材料未来的研究及开发方向进行了展望。     

球磨大豆秸秆在LiCI／DMSO全溶体系中的溶解-再生性能

对大豆秸秆纤维形态、化学成分及球磨预处理后秸秆原料在8％LiCl／DMSO全溶体系中的溶解一再生性能进行了详细研究。大豆秸秆纤维长度明显较短,宽度较大,长宽比比其他秸秆纤维小;其灰分和二氧化硅含量比多数木材原料高,比麦草、玉米秆等原料低很多;其不同部位木质素、综纤维素、抽出物、蛋白质及各种无机元素等成分相差较大。利用8％LiCl／DMSO溶剂体系溶解球磨茎秆和荚组分后发现,球磨时间延长,溶解性能越好,球磨时间达4h,可完全溶解形成澄清透亮的均一溶液。溶解后样品经水再生,产物得率随球磨时间的延长而降低,且在溶解一再生过程中木质素和多糖会有较多损失,多糖损失大于木质素的损失,灰分和硅能得到较好保留。     

几种木质纤维的热稳定性能的研究

近十年来,我国生产的各种木塑复合材料大多采用木粉、稻糠为主要原料,其他木质纤维在木塑复合材料中的应用研究甚少。本文对松木粉、稻糠、竹粉、稻草纤维和麦秸纤维等5种木质纤维的热稳定性能及其在PE基木塑复合材料中的应用效果进行了对比研究。研究表明:5种木质纤维的热稳定性能相近,所得HDPE基木塑复合材料的物理机械性能也相近,均可用于制备PE基木塑复合材料。     

白腐菌木素过氧化物酶发酵条件及其酶液对稻草降解的研究

研究营养条件对白腐菌合成木素过氧化物酶(ligninperoxidase,LiP)的影响。在最适培养条件下,第6天获得7560U/L的酶活。利用LiP粗酶液在体外直接降解稻草,3天后Klason木素的降解率为8.7%,经红外光谱分析其降解产物,推断LiP粗酶液在体外降解稻草的反应主要是氧化反应。     

Spouted Bed Drying as a Method for Enzyme Immobilization

Usually immobilization is a requirement for the use of enzymes as an industrial biocatalyst. In this work, endophytic fungus Cercospora kikuchii lipase was immobilized by covalent binding on agricultural by-products and microcrystalline cellulose. The enzyme support system was submitted to spouted bed drying. Lipase immobilized on microcrystalline cellulose with 1.5% of glutaraldehyde showed the best results, presenting 179.1% of the original activity after drying, followed by rice husk (173.9%), corn stover (169.8%), sugarcane bagasse (157.3%), green coconut fiber (102.3%), and corncob (99.8%). The immobilized derivatives obtained showed a decreased enzyme activity with an average of only 17.31%, whereas the enzyme in its free form lost 85.8% of its initial activity after storage for 6 months. The operational stability showed that the biocatalysts prepared retained an average of 67.2% of the initial activity after five reuse cycles. The results showed that the use of agricultural by-products as low-cost support material associated with the spouted bed drying is promising and can contribute to industrial application of biocatalysts.     

天然植物原料改性聚氨酯及其应用

综述了含天然纤维素的植物原料在聚乙二醇和聚酯多元醇中进行液化及制备改性聚氨酯(PU)。介绍了植物纤维改性PU、玉米秸杆改性PU、稻草改性PU、甘蔗渣改性PU、树皮改性PU的性能及应用。重点介绍了树皮的主要成分单宁改性淀粉PU的耐水性、抗菌性和热稳定性。这些植物原料通过液化改性可替代部分石油多元醇,以满足性能各异的高附加值聚氨酯的要求及在卫生、家具、食品包装和保温隔热等领域中的应用。