An in situ assay for induced diphtheria-toxin-resistant mutants of diploid human fibroblasts

The sensitivity of diploid human fibroblasts to the cytotoxic effects of diphtheria toxin (DT) depended on the cell growth status. Exponentially growing cells treated with 10^?3-1 lethal flocculating units (LF) of DT/ml for 4 days survived with a frequency of 4 × 10^?4. However, the DT-resistant phenotype of colonies isolated under these conditions was not stable. When the growth of the cells had been arrested by confluence or deprivation of serum growth factors prior to treatment with DT (4 days, 10^?3-0.6 LF/ml), the survival decreased to 2 × 10^?6 and the resistance of isolated colonies was stable. An in situ assay for induced DT-resistant mutants was developed in order to avoid problems associated with the possible reduced viability of the mutants relative to that of wild-type cells. A reproducible and linear dose response was obtained for the induction of DT-resistant mutants by ethylnitrosourea. The mutants were induced with high frequency by this compound (e.g., 10^?3 mutants/viable cell at a 37% survival dose); complete expression of the mutant phenotype occurred after 6 generations of growth under nonselective conditions. Isolated mutant colonies showed stable resistance to DT and were cross-resistant to Pseudomonas aeruginosa exotoxin A.     

产紫青霉EL-02的分离鉴定及其絮凝活性

摘要：【目的】分离鉴定有絮凝活性真菌,同时对其絮凝活性进行初步研究。【方法】采用梯度稀释、平板划线、18S rDNA检测等方法分离鉴定絮凝活性菌株。通过高速离心、超声破碎、乙醇沉淀、定性试验等方法确定絮凝活性物质性质。【结果】从渤海湾海岸土壤样品中分离筛选出一株有较高絮凝活性的真菌,经鉴定为产紫青霉（Penicillium purpurogenum）,命名为产紫青霉EL-02（P. purpurogenum EL-02）。超声破碎试验证实其絮凝活性主要存在于发酵上清液。根据絮凝活性曲线,确定4 d为积累絮     

高效微生物絮凝剂D6对屠宰废水的应用研究

筛选出一株针对屠宰废水有高效絮凝活性的微生物絮凝剂产生菌,并对其所产微生物絮凝剂D6进行单因子絮凝条件优化和正交试验优化得到最佳絮凝条件。絮凝条件包括:微生物絮凝剂D6投加量、pH、金属离子种类、1%CaCl₂投加量。试验中发现碱性环境是微生物絮凝剂D6发挥絮凝活性的前提,表明微生物絮凝剂D6分子链的充分伸展对絮凝作用起决定因素,因此微生物絮凝剂D6的絮凝机理为吸附架桥作用。其最佳絮凝条件为微生物絮凝剂D6的投加量为25mL·L^-1,1%CaCl₂投加量55mL·L^-1,pH为8。在最佳絮凝条件下,絮凝率为96.6%,浊度去除率为97.8%,SS去除率为92.6%。     

壳聚糖絮凝法精制合欢皮多糖水提液的工艺

采用壳聚糖对合欢皮总多糖的絮凝纯化工艺进行研究。通过单因素和正交试验,得到优化的工艺条件:壳聚糖用量为生药量0.8 mL/g,絮凝温度35℃,絮凝时间4 h,药液浓缩比(质量体积比)为1∶10(g/mL),在此条件下,多糖保留率、脱蛋白率和多糖纯度分别为91.23%、22.26%和47.27%,优于传统的水提醇沉法。     

微生物絮凝剂产生菌的筛选及其特性研究

高活性微生物絮凝剂在废水处理方面起着非常重要的作用。从兰州佛慈中药制药厂废水池旁采集的土样中分离筛选出了具有絮凝活性的微生物菌种4株(C-5、G-12、G-2、N-7)。对其中3株絮凝率较高菌株的生长量、pH值变化、絮凝活性的分布进行了研究分析。结果表明G-2菌和C-5菌的最佳培养时间为60h,G-12菌为72h。它们的最高絮凝率分别为89.52%(G-2)、82.73%(C-5)、83.18%(G-12)。G-2菌和C-5菌产生絮凝效果的最高活性部位在菌体中而G-12菌则在上清液中。     

絮凝酵母吸附Cr(VI) 的机理

絮凝酵母SPSC01为酿酒酵母Saccharomyces cerevisiae和粟酒裂殖酵母Schizosaccharomyces pombe的融合菌株,用其吸附水溶液中的重金属Cr(VI),可以大大降低生物吸附的固液分离成本。为了探讨SPSC01菌体絮凝蛋白对Cr(VI) 还原吸附的影响,对SPSC01与其亲本菌株的吸附行为进行了比较。结果表明,SPSC01和其具有絮凝性状的亲本S. pombe的Cr(VI) 去除速率基本同步,远优于无絮凝性状的亲本S. cerevisiae;达到吸附平衡时,S. pombe、SPSC01和S. cerevisiae对总Cr去除率分别达68.8％、48.6％和37.5％;从而证明了絮凝有利于Cr(VI) 的还原、吸附,絮凝蛋白在Cr(VI) 的还原吸附过程中起促进作用。通过化学屏蔽方法和傅立叶变换红外光谱 (FTIR) 分析,对SPSC01菌体表面吸附Cr(VI) 的机理进行了研究,结果表明SPSC01菌体表面吸附Cr(VI) 起主要作用的基团是氨基、羧基和酰胺基。     

微生物絮凝剂产生菌的选育及絮凝特性研究

目的:从土壤中筛选具有良好絮凝活性的菌株进行优化培养并研究其絮凝特性。方法:采用平板划线法分离纯化获得目的菌株,通过单因素和正交实验确定最适培养、絮凝条件,考察该菌的生长及产絮凝剂的周期和絮凝活性分布等特征,及其对次甲基兰的脱色能力。结果:得到絮凝活性较高的菌株C5,其最适产絮条件为:初始pH值7.5,温度36℃,培养时间48h;最适培养基为:葡萄糖10g,KH2PO42g,K2HPO45g,(NH4)2SO40.2g,尿素0.5g,酵母膏0.5g,NaCl0.1g,MgSO4.7H2O0.2g,絮凝率可达92.0%;最适絮凝条件为:2.5mL发酵液,pH6.0,5mL CaCl2溶液;絮凝活性成分主要为多糖和蛋白质,多分布于胞外上清液中;发酵液的絮凝活性与细胞生长量均在培养48h时达最大;对次甲基兰的脱色能力优于硫酸铝和聚丙烯酰胺,2min内脱色率可达97%。结论:菌株C5可产高絮凝活性的絮凝剂,具有良好的应用前景。     

Novel bioflocculant produced by salt-tolerant,alkaliphilic strain Oceanobacillus polygoni HG6 and its application in tannery wastewater treatment

The optimized production of MBF-HG6, which is a novel salt-tolerant alkaliphilic bioflocculant produced by Oceanobacillus polygoni with its application in tannery wastewater treatment was investigated in this study. It was found the optimal carbon source, nitrogen source, cation, and initial pH of the medium for bioflocculant production were starch, urea, Fe²⁺, and pH 9.0, respectively. The best stability in the temperature range was from 0 to 80°C and the purified MBF-HG6 contained polysaccharides of 81.53% and proteins of 9.98%. The carboxyl, hydroxyl, and amino groups were determined in bioflocculants, while the optimized bioflocculating activity was observed as 90.25% for the dosages of 6.96mL MBF-HG6, 4.77mL CaCl₂ (1%, m/v), and 19.24g/L NaCl using response surface methodology. In addition, SS and turbidity removal rates of the tannery wastewater (4g/L MBF-HG6) could, respectively, reach 46.49% and 91.08%, indicating that the great potential was emerged in enhancement of tannery wastewater treatment by MBF-HG6.     

生物絮凝剂絮凝活性评价方法的探讨

对生物絮凝剂絮凝活性的评价方法进行了探讨。研究发现,在固定絮凝剂添加量的情况下仅仅比较絮凝率大小,从而对絮凝活性进行评价的方法是不科学的。絮凝剂絮凝活性应以絮凝率和絮凝剂最适添加量两个指标为其活性评价参数,在有较高絮凝率的情况下,絮凝剂添加量越少则絮凝活性越高。     

融合株SPSC发酵生产酒精的工艺研究——自絮凝细胞颗粒粒径分布、细胞生长和产物酒精生成动力学

在测定了融合株SPSC自絮凝颗粒分布的基础上,研究了其培养过程细胞颗粒生长和连续发酵过程产物酒精生成的动力学规律,建立了如下的动力学模型： μ= 0.134S 19.23+S υ=0.747S 10.871+S［(1-SXp126 3SX 2.593］