B.t.与敌百虫、氰戊菊酯对棉铃虫的联合作用

选用棉铃虫幼虫,用饲料混毒法了Ｂ．ｔ．均敌百虫和氰戊菊酯混用的增效作用,结果表明：（１）对２龄幼虫,敌百虫与Ｂ．ｔ．以１：３相混时显著增效;极少量Ｂ．ｔ．也明显增加敌百虫的毒力,同样,敌百虫与Ｂ．ｔ．２．５：１与５：１混合时对５龄幼虫也明显增效;（２）当氰戊菊酯与Ｂ．ｔ．中加入少量氰戊菊酯或氰戊菊酯中加入少量Ｂ．ｔ．以１”６．８相混时拮抗;而Ｂ．ｔ．相混,明显缩短了后对棉铃早思虫的作用时间。     

菜丰宁B1浓缩菌粉的防病机理、生产工艺及应用技术研究

经工业化生产制得的微生物农药丰宁Ｂ１浓缩菌粉是防治大白菜软腐病的活菌制剂。根据１９９４～１９９５年的田间试验,菜丰宁Ｂ１菌剂的防病效果可达５１．８％～８０％,且具有显著的促生作用,增产比对照提高１４．６％。     

Immobilization of <Emphasis Type="Italic">α</Emphasis>-amylase from <Emphasis Type="Italic">Bacillus licheniformis</Emphasis> on developed support using microbial transglutaminase

α-amylase from Bacillus licheniformis was successfully immobilized on developed support, which was prepared by coating a chitosan-casein film on silica, at 20 °C, pH 6.0 for 5 hr with microbial transglutaminase (MTG) as the cross-linking factor. The optimal support was obtained when 1% chitosan and 1% casein were used in the coating mixture. The optimal condition for immobilization catalyzed by MTG was confined to be at MTG concentration of 15 U/mL, pH 6.0, reacting for 6 hr at 20 °C. The highest specific activity of immobilized α-amylase was achieved as 236 U/g. After immobilization, the obtained enzyme showed broader pH profile and maintained more than 70% of the original activity after 20 reuses.     

Optimization of growth medium for the production of α‐amylase from Bacillus amyloliquefaciens using response surface methodology

The optimization of nutrient levels for the production of α‐amylase by Bacillus amyloliquefaciens was carried out using response surface methodology (RSM) based on the 2³ factorial central composite design (CCD). This procedure limited the number of actual experiments performed while allowing for possible interactions between three components. RSM was adopted to derive a statistical model for the effect of starch, peptone and yeast extract (YE) on α‐amylase production. The P‐value of the coefficient for linear effects of starch and YE concentration was <0.0001, suggesting that this was the principal experimental variable, having the greatest effect on the production of α‐amylase. The optimal combinations of media constituents for maximum α‐amylase production were determined as 12.61 g L^?1 starch, 2.83 g L^?1 peptone and 1.25 g L^?1 YE. The optimization of the medium resulted not only in a 34% higher enzyme activity than unoptimized medium but also in a reduced amount of the required medium constituents. Copyright © 2006 Society of Chemical Industry     

Optimization of transglutaminase extraction produced by Bacillus circulans BL32 on solid‐state cultivation

BACKGROUND: This paper reports investigations of the extraction of transglutaminase (TGase) produced by Bacillus circulans BL32 on solid‐state cultivation in order to obtain a crude extract with the highest possible specific activity. The optimization of downstream processing parameters for the effective recovery of the enzyme was carried out using response surface methodology based on the central composite rotatable design (CCRD) to reduce losses in the cultivated solids and to obtain a crude extract as concentrated as possible. Several solvents and temperatures were tested, followed by a 2³ factorial design performed to optimize conditions extraction time, mechanical agitation, and solid:liquid ratio. RESULTS: The mathematical model showed that solid:liquid ratio has a significant negative effect on transglutaminase recovery. The optimal conditions for extraction were: water as solvent at 7 °C; 5 min extraction time; agitation speed 250 rpm; and 1:6 solid:liquid ratio. Under these conditions the model predicts a maximum response of 0.291 U mg^?1 of protein of transglutaminase activity recovery, very closely matching experimental activity of 0.285 U mg^?1 of protein. TGase recovery achieved under the optimized extraction conditions, according to the CCRD, was 2.5‐fold higher than that obtained under non‐optimized conditions previously employed. CONCLUSION: Results show that TGase can be produced in cheap solid state cultivations and the optimization of its downstream processing parameters can improve enzyme recovery in crude extracts and may have important impacts on enzyme costs. Copyright © 2008 Society of Chemical Industry     

甲基营养型芽孢杆菌产氨肽酶的发酵优化

氨肽酶能从多肽链的N端顺序水解并释放氨基酸,广泛应用于食品、工业、医学等领域.该研究利用单因素试验、正交试验及响应面设计试验方法,优化了甲基营养型芽孢杆菌(Bacillus methylotrophilus) CC发酵产氨肽酶的条件.其发酵最佳培养基组成为1％蔗糖、1.5％黄豆饼粉、0.1％氯化钠、0.05％磷酸二氢钾和0.02％硫酸镁.最适发酵条件为初始pH值为8.5,发酵温度37℃,摇床转速180r/min,接种量6％,发酵时间15h.在上述条件下,氨肽酶的产量从优化前的83.09U/mL提高为310.05U/mL,比优化前增加了2.73倍.     

Characterization of L-Arabinose Isomerase in Bacillus subtilis,a GRAS Host,for the Production of Edible Tagatose

L-Arabinose isomerase (AI; E.C. 5.3.1.4), a commercial enzyme for the production of edible tagatose in vitro and ribulose production in vivo, has been studied using enzymes expressed in an Escherichia coli system, which might cause noxious by-products in food. To ensure food safety in the tagatose manufacturing process, we studied an AI expression system in Bacillus subtilis. The AI gene from Geobacillus stearothermophilus (GSAI) was expressed in Bacillus subtilis, a GRAS host used in the production of fermented soybean in Korea, after subcloning into a Bacillus subtilis - E. coli shuttle vector, and was characterized after purification. The activities of the crude enzyme extract and a purified sample were 0.15 U/mg protein and 2.7 U/mg protein, respectively. The optimal pH and the optimal temperature for arabinose and galactose as substrates were pH 8.0 and 60°C, respectively, the same as those for GSAI in an E. coli expression system. Substrate affinities (K_m) for arabinose and galactose were 77 mM and 279 mM, respectively, whereas in the E. coli expression system, they were 100 mM and 578 mM, respectively. Catalytic efficiencies (k_cat/K_m) for arabinose and galactose were 58.3 and 11.4 mM^?1 min^?1, respectively. The potential use of GSAI expressed in a GRAS host for the production of edible tagatose is discussed in light of these results.     

芽孢杆菌生长特性的研究

研究了14株常见芽孢杆菌在不同的水分活度和pH值条件下的生长特性.结果表明:芽孢杆菌对低水分活度(＜0.86)和低pH值(＜4.4)的耐受性均有限,使用柠檬酸来调节pH值能达到更好的抑菌效果.