泡沙参同工酶基因位点的遗传分析

利用聚丙烯酰胺凝胶电泳技术 ,对来自天然群体 (居群 )的泡沙参 (Adenophora potaninii Korsh.)及其人工杂交子代进行了 8种同工酶的电泳检测和谱带遗传分析 ,以确定编码这些酶系统的基因位点和等位基因。选用 4种不同的凝胶缓冲系统 ,对下列不同酶系统进行了酶谱的遗传分析 :天冬氨酸转氨酶 (AAT)、酯酶 (EST)、甲酸脱氢酶 (FDH)、谷氨酸脱氢酶 (GDH)、异柠檬酸脱氢酶 (IDH)、乳酸脱氢酶(LDH)、苹果酸酶 (ME)和超氧化物歧化酶 (SOD)。结果表明 ,这 8种酶系统至少由 1 8个基因位点编码 ,其中 1 2个位点为遗传稳定的等位酶位点 ,是可靠的遗传标记。酶谱的分离式样表明 ,EST为单聚体结构 ,AAT、FDH、IDH、SOD为二聚体结构 ,GDH为六聚体结构。最后对同工酶的器官和发育特异性以及同工酶基因位点的遗传分析进行了讨论     

荧光假单胞菌抗噬菌体菌株的选育

本实验从荧光假单胞菌（Ｐｓｅｕｄｏｍｏｎａｓｆｌｕｏｒｅｓｃｅｎｓ）ＡＳ—３菌株的不正常发酵液中分离到一种噬菌体,将其命名为ＰＦＡＳ。ＡＳ—３菌株能利用葡萄糖发酵产生Ｄ－异维生素Ｃ的前体物质２－酮基－Ｄ－葡萄糖酸。电镜观察表明ＰＦＡＳ噬菌体呈蝌蚪形,具有直径为６６ｎｍ的六角形头部及长１１７ｎｍ的尾部。通过紫外线诱变及自然选育两种途径,配合简便有效的初筛方法,经多次分离、纯化、复筛最终在摇并发酵试验中获得６株产量稳定地高于对照敏感菌的抗噬菌体菌株,可望用于生产。     

Charactererization of novel non-toxic Bacillus thuringiensis isoloates from Korea

J.Y. ROH, H.W. PARK, B.R. JIN, H.S. KIM, Y.M. YU AND S.K. KANG. 1996. Four Bacillus thuringiensis isolates from soil samples produced parasporal inclusions which were non-toxic to insects. The isolates were named B. thuringiensis NTB-1, NTB-2, NTB-3 and NTB-4. The parasporal inclusions were shown to be ovoid by phase contrast and scanning electron microscopy. The serotypes of the four isolates were determined by agglutination using 33 antisera; NTB-1 and NTB-4 seemed to be subsp. isruelensis ,and NTB-2 seemed to be subsp. pondzcheriensis . NTB-3 did not react with the 33 antisera. However, comparison of parasporal protein and plasmid DNA patterns of the four isolates with those of 15 known non-toxic B. thuringiensis strains demonstrated that the four isolates are novel.     

Role of acetylation on metal induced precipitation of alginates

Acetylation dramatically effects both the solution properties and the metal induced precipitation of alginates. The presence of acetyl groups on both bacterial and seaweed alginate polymers marginally increased the weight average molecular weight (M_w) of each polymer by 7% and 11%, respectively. Acetylated bacterial alginate showed a significant increase in solution viscosity compared to its deacetylated counterpart. However microbial acetylation of seaweed alginate did not change its solution viscosity. Acetylation altered the calcium induced precipitation of both alginates. The presence of acetyl groups decreased the ability of each polymer to bind with calcium but increased their ability to bind with ferric Ion (Fe³⁺). By controlling the degree of acetylation on the alginate chains, it was possible to modify solution viscosity and cation induced precipitation of these polymers.     

Cellobiose-oxidizing enzyme from a newly isolated cellulolytic bacterium Cytophaga sp. LX-7

Summary The cellobiose oxidizing enzyme of the newly isolated cellulolytic bacterium Cytophaga sp. LX-7 was produced extracellularly when grown on cellulose or other saccharides, which was previously noted only in fungi. The enzyme could use not only cellobiose, maltose, glucose and other saccharides but also cellulose as substrates, and use dichlorophenol indophenol and oxygen as electron acceptors.     

Comparative study of nickel toxicity to growth and photosynthesis in nickel-resistant and -sensitive strains of Scenedesmus acutus f. alternans (Chlorophyceae)

Nickel (Ni) toxicity to growth and photosynthesis was studied in four strains of Scenedesmus acutus f. alternans. Effects of Ni dosage and duration of exposure on growth and photosynthesis were strain specific. Large differences in responses of both growth and photosynthesis to Ni were detected between three resistant strains (B4, Cu-Tol, and Ni-Tol) and one sensitive strain (UTEX 72). Growth of UTEX 72 was 18 times more sensitive to Ni than those of the three resistant strains. The order of Ni dosages (fmol Ni/pg cell dry weight) causing 50% inhibition (D₁₅₀) of growth rates in the four strains was Ni-Tol (10.5) > B4 (8.19) > Cu-Tol (4.60) > UTEX 72 (0.25). The effect of Ni dosage on photosynthetic rate as percentage of control corresponded to a saturation curve and was a strong function of duration of exposure. The DI₅₀s of photosynthetic rates were 3.5 times lower in UTEX 72 than in the three resistant strains, and in all four strains they decreased sharply with the increase in duration of exposure. The order of the four strains in DI₅₀s of photosynthetic rate was B4 (58.2) > Cu-Tol (38.0) > Ni-Tol (28.9) > UTEX 72 (8.24) for 6-h exposure and Ni-Tol (2.88) > Cu-Tol (1.30) > B4 (1.01) > UTEX 72 (0.15) for 24-h exposure. The DI₅₀s of photosynthetic rate for 6-h exposure were higher than those of growth rate in all four strains, and for 24-h exposure they were lower, except in UTEX 72. Thus, the relative Ni sensitivity of growth and photosynthesis of the four strains depends on the duration of exposure. The results of factorial analysis of variance suggested that Ni toxicity to photosynthesis is a consequence of a strong interaction among strain, Ni dosage, and duration of exposure.     

生物复苏——大绝灭后生物演化历史的第一幕

生命史是一部生物界短期,快速剧变与长期,慢速稳定相互交替的历史。大绝灭（即集群绝灭）事件反映了全球环境的大突变,点断了地质历史中的生命记录及其发展历程,预示着生物界的演化出现了最有意义的飞跃,近年来尝试研究大绝灭后全球生物界的残存－复苏及其基本型式,并探索复苏的控制因素,标志着地质科学中一个重心的转移（即从大绝灭转向其后的生物残存与复苏的研究）。生物复苏揭示了大绝灭后生物演化历史的第一幕,其研究的     

融合株SPSC发酵生产酒精的工艺研究 Ⅰ.絮凝速率、发酵过程的最适温度和pH值

酿酒酵母属(S. cereviae)变异株和粟酒裂殖酵母属(S. pombe)变异株进行属间原生质体融合得到融合株SPSC,该融合株比S. cereviae具有强的自身絮凝能力。以葡萄糖浓度150g/L的底物在30～44℃的温度范围内进行摇瓶厌氧发酵,获得最佳温度范围为34～38℃,最高发酵温度为40℃。在有效容积2.35L悬浮床反应器中,在pH值3.0～5.0范围内进行连续发酵,获得最适发酵pH为3.5～4.5。     

部分酶解酵母高效电击转化研究

以酵母质粒YCp50为外源DNA,电击转化部分酶解酵母宿主菌AB1380,转化效率稳定在10~6转化子/μg质粒DNA左右,比不酶解酵母或酵母原生质球作受体的电击转化效率高一个数量级以上,也比PEG介导的酵母原生质球转化高3～5倍,而且适合于大片段DNA如水稻YAC分子的转化。达最佳转化时的有关技术参数为:新接菌种通气培养至细胞密度1×10~8～1.5×10~8个/ml;转化时细胞密度控制在1×10~9～1.5×10~9个/ml;每毫升酶解缓冲液加15u溶菌酶(lyticase),30℃下处理酵母5min进行部分酶解;电击时,电场设置在6.25kV/cm、电容25μF,电击后直接铺板。     

微菌落观察法快速检测和鉴别结核杆菌培养物的研究

将取自肺结核患者的219例痰标本接种匡氏琼脂平板,共分离到112例结核菌生长物。其中培养法104例(92.8％)阳性,微菌落观察法108例(96.4％)阳性,微菌落法阳性率稍高。培养法和微菌落法阳性标本首次检出时间分别为18.6d和11d,微菌落检出时间更短(P<0.01)。常规菌型鉴别方法与微菌落法对结核杆菌菌型鉴别的符合率为99％。