培养基成分对里氏木霉合成木聚糖酶的影响

以里氏木霉(Trichoderma reesei)Rut C-30为产酶菌,研究了碳源、氮源和碳氮比对木聚糖酶合成的影响.结果表明粗木聚糖和亚硫酸盐纸浆混合作为碳源有利于木聚糖酶的合成,碳源中随着亚硫酸盐纸浆含量的增多,合成的木聚糖酶活先上升后下降,当碳源为粗木聚糖(5g/L)与亚硫酸盐纸浆(2g/L)的混合物时,木聚糖酶活最高,与单独用7g/L的粗木聚糖为碳源相比,木聚糖酶活提高了56.66%.混合氮源的产酶效果比单一氮源的产酶效果好,其中尿素、蛋白胨和酵母浸膏按一定的比例混合作为氮源产酶效果最好,木聚糖酶活达138.56 IU/mL,单一氮源中有机氮源产酶效果比无机氮源稍好.随着碳氮比的增加,木聚糖酶活值先上升后下降,以粗木聚糖为碳源,里氏木霉合成木聚糖酶的较适碳氮比为7.2左右.     

直接降解木质素的漆酶/木聚糖酶体系的合成

对一株高产漆酶及伴有木聚糖酶和少量纤维素酶的菌株,用不同的碳源和氮源对其调控培养,合成漆酶/木聚糖酶体系。实验结果表明,最佳的碳源是可溶性淀粉,用它作碳源,漆酶活性高达730IU/mL,木聚糖酶活性是4.49IU/mL,纤维素酶活性只有0.23IU/mL;最佳的氮源是蛋白胨,用其作氮源,合成漆酶活性可达812IU/mL,木聚糖酶活性是4.68IU/mL,纤维素酶活只有0.09IU/mL。     

粗糙脉孢菌(Neurospora crassa)木聚糖酶的合成及性质研究

粗糙脉孢菌1602(Neurosporacrassa)可以产生木聚糖酶。以不同的植物纤维物料及纯木聚糖作为底物都可诱导产生较高的木聚糖酶活,其中玉米芯粉的诱导能力最强,酶活可达25.02IU/mL。纤维素与木聚糖混合对木聚糖酶合成具有促进作用。葡萄糖、木糖对木聚糖酶的合成有很强的阻遏作用,葡萄糖的阻遏作用大于木糖的阻遏作用。其木聚糖酶最适作用pH值为5.4,最适作用温度为60℃。     

一株产木聚糖酶菌株的筛选及发酵产酶条件优化

以木聚糖为唯一碳源,从含有大量腐烂枯枝树叶土壤中筛选到一株高产木聚糖酶菌株,经形态学分析和分子学鉴定,确定其为链霉属(Streptomyces)。通过单因素实验考察了碳源、氮源、初始pH值、发酵温度和发酵时间对酶活的影响;在单因素实验的基础上,利用Design-Expert软件对碳源、氮源和发酵时间进行响应面分析。单因素实验确定适宜发酵产酶条件为:复合碳源为玉米芯粉+蔗糖(1∶2)、氮源为硝酸铵、初始pH值4.0、发酵时间2.5d、发酵温度30℃,此时,所产木聚糖酶酶活为511U·mL~(-1);响应面分析确定最优发酵产酶条件为:复合碳源(玉米芯粉∶蔗糖=1∶2)添加量4.09%、氮源硝酸铵添加量1.16%、初始pH值4.0、发酵时间3.14d、发酵温度30℃,此时,所产木聚糖酶酶活达到641U·mL~(-1),较单因素实验提高了25.44%。     

低聚木糖生产用木聚糖酶的选择性合成

以里氏木霉(Trichoderma reesei)Rut C-30为产酶菌,研究了碳源、碳氮比对木聚糖酶酶系组成的影响.低分子量组分较多的木聚糖有利于促进内切-β-木聚糖酶的合成,酶解产物中低聚木糖的含量较高(80.70%).低碳氮比有利于促进内切-β-木聚糖酶的合成,抑制外切-β-木糖苷酶的合成.以低分子量较多的木聚糖(7g/L)为碳源,降低培养基的碳氮比为4.0,调控培养60h,用该木聚糖酶酶解粗木聚糖,产物中低聚木糖占总糖的86.32%.     

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。     

绿色木霉合成几丁质酶条件的研究

绿色木霉ＺＵ０１１在以０．５％几丁质为唯一碳源的培养基中几丁质酶活达到０．１２４ＩＵ／ｍＬ。几丁质酶合成的最佳碳源和诱导物为几丁质。在一定范围内啬２基中几丁质浓度,葡萄糖浓度,微量元素盐浓度和碳氮比都能提高几丁质酶活。胆汁酸和吐温８０作为表面活性剂能显著提高几丁质酶活。     

荧光假单孢菌高活性木聚糖酶产酶研究

从盐碱土中获得一样荧光假单孢菌（P.flu．01）,研究了该菌木聚糖酶产酶条件。虽然木聚糖为木聚糖酶产酶最佳碳源,但以未处理的玉米芯为碳源,胰蛋白际和酵母混音为氮源时．经60h培养后,木聚糖酶活高达164．OIU／mL,而CMC酶活很低,只有0．29IU/mL。同时该菌对pH值具有广泛的适应性,在起始pH＝6．0－11．0范围内其木聚糖产酶能力相差不大。有机氛胰蛋白股和酵母混音比无机氛更有利于酶活的提高,并且木聚糖酶活力的提高和有机氟含量增加成正比。玉米芯的物理状态即粗细度对产酶影响不大,但玉米芯的含量增加对广酶有强烈的挺进作用。该酶最合适pH值为6．5,最适反应温度为50℃。     

木聚糖成分对木聚糖酶合成的影响

分别以两种含有不同组成的木聚糖为碳原进行产酶研究,结果发现木聚精成分对里氏木霉产木聚糖酶的效果具有重大影响。实验结果表明,用全组分的木聚糖（即用酒精等有机溶剂沉淀下来的木聚糖）诱导合成本聚糖酶的效果要比仅以水不溶性高聚合度木聚糖的效果好。当以全组分的木聚糖为碳源产酶时,不仅产酶周期缩短（仅需2．5d）,而且有利于提高木聚糖酶活力,酶活力、比活力、酶得率及酶产率分别达到34．27IU／mL、78．21;IU／g蛋白质、4895．7IU／g木聚糖和13708．0IU／L·d,酶活力和酶产率分别是以水不溶性木聚糖为碳源时的2．7倍和3．3倍。     

玉米芯木聚糖硫酸酯的合成、表征及其抗凝血活性

以碱法提取的玉米芯木聚糖为原料,LiCl为催化剂,在非质子溶剂中,采用三氧化硫-吡啶法合成了玉米芯木聚糖硫酸酯（XS）,通过正交试验对合成工艺进行了优化,并采用凝胶渗透色谱（GPC）、红外光谱（FT-IR）、元素分析和¹³C NMR对其结构与性能进行了表征,进一步考察了其体外抗凝血活性。结果表明：在DMF溶剂中,当三氧化硫-吡啶络合物与木糖羟基单元的物质的量之比为1.5：1时,于55℃反应3 h,木聚糖的酯化效果最好,所制备的XS的取代度（D_S）为1.53,得率为78.2%,重均相对分子质量为36 754,分散系数为1.191。结构表征发现,硫酸酯基已经成功引入木聚糖中。体外抗凝血活性结果表明：XS可以延长APTT和TT,具有一定的抗凝血活性;当取代度为1.53、质量浓度为20 mg/L时,XS的APTT、PT和TT分别为36.37、14.22和14.70 s,与阳性对照肝素钠基本相当。     

Effect of Natural and Pretreated Soybean Hulls on Enzyme Production by Trichoderma reesei

The enzyme induction utility of soybean hulls (SBH), consisting in excess of 50 wt% non-starch polysaccharides (NSP) cellulose, hemicellulose, and pectin, was studied through cultivation of the carbohydrase-producing fungus Trichoderma reesei Rut C-30. Shake flask systems of T. reesei were grown in a medium consisting of defatted soybean flour as a nitrogen source and SBH, some of which were untreated and others pretreated by liquid hot water, alkaline, and supercritical carbon dioxide, as carbon source. Cellulase, xylanase, and polygalacturonase activities were measured for the systems, and the natural hull systems were found to yield optimum enzyme production. Controlled batch fermentation experiments were carried out to compare enzyme production resulting from media with Avicel^® (FMC BioPolymer, Philadelphia, PA, USA) versus natural SBH with and without soybean flour as the nitrogen source. Soybean hull fermentations were also performed at several pH levels to observe the effects on enzyme production. Soybean hulls induced comparable levels of cellulase, and higher levels of xylanase and polygalacturonase, than Avicel^®. With SBH, cellulase and xylanase production were enhanced at higher pH levels (6.0), and polygalacturonase was enhanced at lower pH levels (4.0–4.5). Enzyme production was largely unaffected by the presence of soybean flour as the nitrogen source.     

乙酸钠外加碳源SBBR工艺脱氮效果的实验研究

选取乙酸钠为外加碳源,采用SBBR工艺处理低C/N比城市生活污水。当外加碳源后的C/N比值增加至7.0左右时,对原水NH4+-N去除率最高为89.31%,外加碳源后的C/N为7.12时,TN的去除率最好,为71.27%。结果表明,外加乙酸钠碳源后的SBBR工艺对于低C/N生活污水脱氮性能十分良好。出水水质指标均达到了《城镇污水处理厂污染物排放标准》(GB18918-2002)中的"一级标准A标准",出水作为回用水。     

碳氮比与氨氮负荷对序批式活性污泥法同步硝化反硝化的影响

为了提高生物脱氮的效率,研究采用序批式活性污泥法(SBR工艺)考察碳氮质量比w(C/N)与氨氮负荷对同步硝化反硝化的影响。结果表明:当w(C/N)为5.6,氨氮负荷为0.024 g/(g.d),碳源快速消耗,SBR工艺较难实现同步硝化反硝化,同步硝化反硝化率只能够达到0.76%。当w(C/N)为10.5,氨氮负荷为0.024 g/(g.d)时,SBR系统能够实现同步硝化反硝化,同步硝化反硝化率达到97.6%,NH4+-N和COD去除率均接近100%;当w(C/N)为16.3,氨氮负荷为0.024 g/(g.d)时,同步硝化反硝化率为94.5%,增加外加碳源的成本。同步硝化反硝化可以取代二段独立的硝化和反硝化过程,节省运行费用。     

有机碳源添加对脱氮副球菌脱氮效果的影响

以脱氮副球菌(Paracoccus denitrificans)为菌种来源,可生物降解聚合物PCL为有机碳源和生物膜载体,对养殖水体的硝酸盐氮进行脱除实验。结果表明,以特定反硝化菌株接入反硝化装置,可以有效去除硝酸盐氮和亚硝酸盐氮。经过15 d的驯化,60 d的反硝化实验,硝酸盐氮的去除率达到79%,且无亚硝态氮的明显累积;扫描电镜结果表明,固相碳源表面形成的凹陷可为脱氮副球菌提供碳源及载体,具有较好的生物利用性。以PCL为碳源,可以提高养殖水体中的C/N,且操作简单,在经济上具备一定的可行性。     

Nitrogen removal characteristics of heterotrophic nitrification-aerobic denitrification by Alcaligenes faecalis C16

Alcaligenes faecalis C16 was found to have the ability to heterotrophically nitrify and aerobical y denitrify. In order to further understand its nitrogen removal ability and mechanism, the growth and ammonium removal response were investigated at different C/N ratios and ammonium concentrations in the medium with citrate and acetate as carbon source separately. Furthermore, experiments of nitrogen sources, production of nitrogen gas and enzyme assay were conducted. Results show that the bacterium converts NH4+-N and produces NH2OH during the growing phase and nitrite accumulation is its distinct metabolic feature. A. faecalis C16 is able to tolerate not only high ammonium concentration but also high C/N ratio, and the ammonium tolerance is associated with carbon source and C/N ratio. The nitrogen balance under different conditions shows that approximately 28%–45%of the initial ammonium is assimilated into the cells, 44%–60%is denitrified and several percent is converted to nitrification products. A. faecalis C16 cannot utilize hydroxylamine, nitrite or nitrate as the sole nitrogen source for growth. However, nitrate can be used when ammonium is simultaneously present in the medium. A possible pathway for nitrogen removal by C16 is suggested. The preliminary enzyme assay provides more evidence for this nitrogen removal pathway.     

Characterization of cellulase and xylanase activities of Clostridium celerecrescens

The production of cellulases and xylanase by Clostridium celerecrescens, a new anaerobic mesophilic cellulolytic bacterium, was studied using various substrates (cellobiose, xylan and cellulose Whatman CF-11). While both cellulase (β-1,4-D-glucan glucanohydrolase) and xylanase (β-1,4-xylan xylanohydrolase) were produced on cellulose, only the latter was produced when xylan was used as the sole carbon source. A weak p-nitrophenyl-β-D cellobiohydrolase activity was detected in the extracellular filtrates when using cellulose as a substrate. Otherwise, β-glucosidase (p-nitrophenyl-β-D-glucopyranosidase) was always found to be associated with the bacteria and reached its maximum levels of growth on cellobiose. In all cases, enzyme production showed a cell growth associated profile. Activities of these enzymes had their optimal values within the ranges of temperature and pH reported for the corresponding enzymes from similar anaerobic mesophilic microorganisms, although a relatively high optimum temperature, 55°C, was found for xylanase. All enzymes showed a 90% reduction of half-life time for each 8°C increment of temperature. A 50% inhibition of xylanase and β-cellobiohydrolase activity was observed, through a competitive mechanism, by xylose (0.677 mmol dm^?3) and cellobiose (28 mmol dm^?3) respectively.     

Xylanase production by Bacillus polymyxa

Bacillus polymyxa produced high levels (12–13 U cm^?3) of extracellular xylanases when grown in a complex medium containing yeast extract and oat spelt xylan as nitrogen and carbon sources respectively. Substantially lower yields of enzyme were produced during growth on the monosaccharides glucose, arabinose and xylose. Meagre growth occurred when ammonium sulphate, instead of yeast extract, was used as nitrogen source. When assayed in culture broth supernatants, xylanase showed an optimum activity in 48°C and at pH values in the range 5.0–6.5. Under such conditions, the half-life of this xylanase preparation was 8 h. Mn²⁺ showed a strong inhibitory effect on the enzyme, but inhibition by EDTA (27% w/v) suggested dependence on a metallic ion. SDS-PAGE and zymogram overlay showed that up to five separate xylanases in the range of 20 to 116 kDa were produced.     

低碳氮比条件下外加铁源对生物脱氮性能与机理的研究

针对高氨氮废水,通过投加微量元素Fe²⁺强化微生物活性,研究低碳源(碳氮比不超过3)条件下外加铁源对活性污泥脱氮性能的影响以及主要反硝化功能基因的变化。结果表明:在低碳氮比(碳氮比为3)条件下,A反应器(ρ(Fe²⁺)=2 mg/L)的TN去除率比B反应器(ρ(Fe²⁺)=0 mg/L)提高了10.4%。持续投加Fe²⁺, A反应器TTC-ETS(电子传递体系)活性整体比对照组B高,同时A反应器中INT-ETS(电子传递体系)活性呈上升趋势,B反应器维持不变。另外,根据荧光定量PCR试验结果表明,在碳氮比为3的情况下,A反应器的活性污泥中narG、 nirK、 nosZ基因拷贝数均高于B反应器。研究表明,投加Fe²⁺有利于增加系统中反硝化菌群丰度,同时促进微生物的电子传递,进而实现TN的去除。