紫外线诱变选育碱性蛋白酶高产菌株

本实验以枯草杆菌A4－3为出发菌株,发酵产生碱性蛋白酶,其野生型菌株产酶为2412u／ml。采用孢子热处理方法处理出发菌株孢子,得到变异株As—4,产酶2732．8u／ml。对As—4菌株进行紫外线绣变处理1min,得变异菌株AX—46,产酶为3213．8u／ml,且产酶能力稳定。     

葡聚糖酶高产菌株的诱变筛选及其摇瓶发酵条件的初步研究

从土壤中分离出的一株产葡聚糖酶酶活31 U／ml的野生菌株,经UV、^60Co、LiCl诱变筛选后得到了产葡聚糖酶高产菌株SB126,经发酵条件优化试验后检测其酶活达到85U／ml,较野生菌株提高了近两倍。葡聚糖酶摇瓶较适发酵条件为：装量30ml(250m1)、转速180r／min、pH7．0、温度30℃、接种量8％、发酵周期5d。     

产适冷木聚糖酶的海洋产青霉的筛选和诱变

从黄海深层海底泥样中分离到1株产低温木聚糖酶的青霉,经EMS诱变得到11株酶活性提高的菌株,对其中1株产低温木聚糖酶活力最高的菌株产酶性质进行了初步研究。所产木聚糖酶在pH4．6,45℃时酶活可达25．8u／ml,比出发菌株提高126％。诱变后菌株所产木聚糖酶在0℃仍有显著酶活性,达8．2u／ml。     

产壳聚糖酶菌株的初步筛选

通过大量的筛选,获得了产壳聚糖酶较好的菌株Y2、Y4、Y8。其发酵液所产壳聚糖酶的酶活力分别为2．0U／ml,2．1U／ml,2．2U／ml。     

芽孢杆菌E2菌株纤维素酶形成条件的研究

芽孢杆菌E,菌株(Bacillus sp.strain E2)能在55℃下良好生长并在培养液中大量积累胞外纤维素酶(190 mu／ml培养液),所产生的纤维素酶为单一的CMCa se。对芽孢杆茁E2菌株产酶条件进行了研究． 该菌产酶的最适培养基装量为200ml/500mI三角瓶,最适起始pH为6 5,最适产酶温度为45℃,产酶高峰在培养时间8—12小时。E2菌株不能利用单一的无机氮源形成纤维素酶。酪蛋白是试验过的供E2菌株形成纤维素酶的最好氮源,其用量为3g／L。CMC—Na,纤维二糖,能作为碳源供芽孢杆菌E2菌株形成纤维素酶。高浓度的葡萄糖(8g／L)对芽孢杆菌E2菌株纤维素酶的形成有抑制作用。天然纤维素不能作为芽孢杆菌E2菌株形成纤维素酶的碳源。     

根霉植酸酶的研究──Ⅰ.菌株的分离筛选及发酵条件研究

从21个土样和15株产酶菌株中筛选到1株产酶能力较强的菌株——根霉（Rhizopussp.）MR020。其优化培养基组成（％）：大米粉2.0,干酪素0．05,（NH4）2SO41.0,MgSO4·7H2O0.05,FeSO4·7H2O0.01,pH5.0。其振荡培养条件：培养基装最25ml／250ml三角瓶,用培养8天、浓度为1×107个／ml的孢子悬液接种1ml,于30℃,150r／min振荡培养108h产酶量最高达4000u/ml。     

产胞外青霉素酰化酶菌株的选育

以短小杆菌（B．pumilus）B－97为出发菌株,经过连续两次紫外线诱变处理,分离得一突变株B－U－29。其酶活力为4．56U／ml,较出发菌株酶活力提高113．3％。对B－U－29菌株进行连续两次亚硝酸处理,分离得一正变稳定株B—H－29,酶活力为4．93u／ml,较出发菌株酶活力提高了20％。     

利用原生质体诱变育种选育富硒能力强的酵母菌株

利用原生质体诱变育种技术选育富硒能力强的酵母菌株,从13株啤酒酵母中筛选出一株富硒量高的诱变出发菌株,采用溶壁酶进行破壁,确定了原生质体制备的最适条件为酶浓度1g／100mL,酶解处理时间为120min,原生质体形成率为95．2％,再生率为21．8％,诱变后筛选出富硒量为821mg／kg,酵母干菌体收获量为0．88g／100mL的酵母菌Al。     

碱性普鲁兰酶产生菌的原生质体制备与诱变选育

研究报道了Bacillus sp SX—12原生质体制备与再生最佳条件。实验表明,在液体完全培养基中加入2％的甘氨酸培养10h,原生质体制备最佳条件为：溶菌酶浓度0．5mg／mL,酶解温度37℃,酶解时间1．5h时原生质体形成率为93．8％。原生质体形成最佳高渗稳定剂为甘露醇,再生率26．4％。在原生质体制备的最佳条件下,用紫外线诱变技术选育产碱性普鲁兰酶的高产菌株。筛选到1株高产菌株SX—12C87,酶活由出发菌株的2．42μ／mL提高到6．87μ／mL,提高了约1．8倍。     

假丝酵母尿酸酶形成条件

选出了一株产尿酸酶的产朊候丝酵母(Candida utilis)AS2．117。此菌株尿酸酶形成条件的研究表明：尿酸、黄嘌呤和鸟嘌呤对酶形成起诱导作用;玉米浆对菌株生长和酶形成起十分重要的作用;蔗糖、葡萄塘、D-甘露糖和果糖是酶形成的适合碳源;生物素对酶产生有促进作用;在含有玉米浆培养基中加入无机氮源对产酶无作用,添加有机氮略增加产酶量。尿酸酶形成最适培养基组成为(％)：蔗糖;,玉米浆3,尿酸0．1,蛋白胨0．1,生物素0．05,KCI0．1,NaCl 0.1。最适pH为6．2。在250ml三角瓶中装30ml培养基为最适。在200r／min的旋转摇床上25℃振荡培养21h,在此条件下最终酶活力可达0．6u／ml。     

酵母SOD形成的生理学研究

对筛选出的一株ＳＯＤ高产菌株Ｙ－２１６形成ＳＯＤ的生理条件作了初步研究。结果表明：碳源、氮源、碳氮配比和金属离子等营养条件及培养温度、时间和通气量等培养条件,均对该菌株生物量与ＳＯＤ含量有较大的影响。同时通过对几种酵母的测定,发现酵母菌对氧的抗性越大其ＳＯＤ含量也就越高。     

Effect of superoxide dismutase(SOD) on pronucleus formation of porcine oocytes fertilized in vitro

This study was undertaken to evaluate the effects of superoxide dismutase (SOD) on pronucleus formation in porcine oocytes fertilized in vitro by frozen-thawed spermatozoa. No differences were found in penetration rates when SOD was added to maturation or fertilization medium at any level tested in first and second experiments. Pronucleus formation rates were higher (P < 0.05) when SOD at 10 and 100 units was added to the maturation medium (46 and 53%, respectively) compared with the controls (26%). On the other hand, when the fertilization medium was supplemented with SOD at different concentrations (1, 10 and 100 units/ml), pronucleus formation rates (55, 52 and 50%) were significantly higher (P < 0.05) than in the control group. In third experiment, the oocytes were cultured in medium with (1 unit/ml) or without SOD for 8, 16, 24 and 32 h after insemination. The penetration rates had a tendency to increase as time of sperm-oocyte culture was prolonged. No significant differences, however, were observed in penetration rates between groups with and without SOD. On the other hand, the pronucleus formation rates were higher in medium with than without SOD at 8 (7 vs 0%), 16 (14 vs 3%), 24 (48 vs 16%; P < 0.01) and 32 h (49 vs 22%; P < 0.05). These findings demonstrate the advantage of culture with SOD on pronucleus formation in porcine oocytes penetrated by spermatozoa. However, SOD does not affect penetration rates and polyspermy.     

高产SOD大蒜悬浮细胞系的选育

筛选获得了高产 SOD大蒜悬浮细胞系 ,培养 1 8d后达到最大生物量及最大 SOD总酶活分别为2 2 .1 2 g.DW/ L及 1 0 .81× 1 0 4 U/ L,最大单位细胞酶活为 679.67U/ g.FW,SOD最大比活力可达 85 .98U/mg Pro,具有较强的 SOD合成能力。     

SOD制剂在椪柑生产上的应用试验

本试验初步探明喷施益微SOD制剂,对椪柑成年结果树的果实SOD活性及品质有良好效应,建议采用0.16g/L SOD制剂进行喷施,每隔30d一次,连续喷布3~4次较为合适。     

Structures of mouse SOD1 and human/mouse SOD1 chimeras

Mutations in human copper-zinc superoxide dismutase (SOD1) cause an inherited form of amyotrophic lateral sclerosis (ALS). Inclusions enriched in pathogenic SOD1 accumulate in the spinal cords of transgenic mice expressing these proteins, but endogenous mouse SOD1 is not found as a component of these aggregates. In the accompanying paper, Karch and colleagues analyze aggregation propensities of human/mouse SOD1 chimeras in cell culture and identify two sequence elements in the human enzyme that seem to enhance its aggregation relative to the mouse enzyme. Here, we report the first structure of mouse SOD1 along with those of SOD1 chimeras in which residues 1-80 come from human SOD1 and residues 81-153 come from mouse SOD1 and vice versa. Taken together, the structural and cell-based data suggest a model in which residues Q42 and Q123 in mouse SOD1 modulate non-native SOD1-SOD1 intermolecular interactions at edge strands in the SOD1 Greek key β-barrel.     

激动素、脱落酸和丙二醛对SOD活性影响及其与SOD构象和疏水性变化间的关系研究

 激动素、脱落酸和丙二醛对ＳＯＤ活性影响及其与ＳＯＤ构象和疏水性变化间的关系研究伍泽堂候万儒（四川师范学院生物系,南充６３７０００）我们在实验中曾发现激动素（ＫＴ）激活小麦ＳＯＤ活性,脱落酸（ＡＢＡ）、丙二醛（ＭＤＡ）抑制小麦超氧化物歧化酶（ＳＯＤ）活...     

益生枯草芽胞杆菌B15的性能检测及培养条件研究

对筛选得到的枯草芽胞杆菌B15进行了产酶及拮抗性能的检测,结果表明该菌株能够分泌淀粉酶、蛋白酶、纤维素酶,同时对常见病原体有一定的拮抗作用,具有作为益生菌进行发酵和研制微生态制剂的潜力。采用单因子试验,对B15菌株的培养液组成（碳源、氮源）及培养条件进行了研究,结果表明：以1.5%葡萄糖及0.5%酵母浸出物制成的培养液,在35℃、初始pH6.5左右,装液量为20 ml/250 ml,接种量2%的条件下培养B15,可将活菌数目从原始的1.15×109CFU/ml提高至1.61×109CFU/ml。     

麦芽糖诱导软化芽孢杆菌α-环糊精葡萄糖基转移酶在枯草杆菌中的表达

通过PCR扩增软化芽孢杆菌α-环糊精葡萄糖基转移酶基因,将基因片段克隆到大肠杆菌-枯草杆菌穿梭载体pGJ103中,转化枯草杆菌WB600得基因工程菌进行外源表达。在1.5%的麦芽糖初始发酵培养基上摇瓶培养,48 h后重组枯草杆菌产酶活性为6.1U/ml。通过单因素分析和响应面分析对重组枯草杆菌产CGT酶摇瓶发酵条件进行优化。分析得到培养基关键组分麦芽糖,玉米淀粉和酵母粉三者最佳浓度分别为:15.5g/L,13g/L和20g/L。在此条件下,摇瓶培养36h后α-CGT酶活性为17.6U/ml,5L罐分批发酵30h后酶活达到20U/ml (水解活性为1.4×10⁴ IU/ml)。     

Enhanced expression of an endoglucanase in Bacillus subtilis by using the sucrose-inducible sacB promoter and improved properties of the recombinant enzyme

An endoglucanase from Bacillus akibai I-1 was successfully overexpressed in Bacillus subtilis 168 and the expression level of the recombinant enzyme was greatly enhanced by using the sucrose-inducible sacB promoter. The endoglucanase activity in the culture supernatant of recombinant B. subtilis by using itself promoter (HpaII) in plasmid pMA5 was 3U/ml. Interestingly, with the addition of sacB promoter at downstream from the HpaII promoter or the replacement of HpaII promoter by the sacB promoter, the endoglucanase activities reached 62 and 60U/ml, respectively, under the optimal culture conditions. These results demonstrated that the sacB promoter might be more efficient for the expression of the endoglucanase than the HpaII promoter. More interestingly, the purified native enzyme had broad pH stability, good thermostability and resistibility to various metal ions and chelating agents examined, while the recombinant enzyme had improved resistibility to SDS, which was stable in 0.2% (w/v) laundry detergent and thus showed great potential in detergents industry.     

植物乳杆菌CLP0279发酵生产低温SOD培养基的优化

【目的】提高植物乳杆菌CLP0279发酵生产低温超氧化物歧化酶(superoxide dismutase,SOD)的能力。【方法】在单因素实验基础上,采用Plackett-Burman (PB)设计、Box-Behnken (BB)设计和响应面分析法(RSM),对发酵培养基进行优化。【结果】植物乳杆菌CLP0279产低温SOD最佳发酵培养基(g/L)：玉米粉25.000,磷酸二氢钾2.600,磷酸氢二钾1.830,硫酸铜0.011,硫酸锌0.014。在最佳培养基条件下产酶活力达到194.82 U/ml,是优化前的1.36倍。【结论】通过响应面分析,对植物乳杆菌CLP0279发酵生产低温SOD的培养基进行优化,明显提高了产酶能力。确定了磷酸氢二钾、硫酸铜和硫酸铵为发酵培养基中影响酶活的3个关键因子。研究结果为SOD的发酵放大提供了依据。