物理诱变处理氧化亚铁硫杆菌的育种研究

以氧化亚铁硫杆菌作为出发菌,采用物理诱变进行处理。研究结果表明,经过微波和超声波诱变均能加快氧化亚铁硫杆菌氧化Fe2+和转化SO32-的速度。尤其是经过90 s微波处理的氧化亚铁硫杆菌进入对数期的时间比未经诱变前缩短12 h,48 h时Fe2+的氧化率达到99%,4小时后SO32-基本全部转化为SO42-。     

再生水中弗氏柠檬酸杆菌生物膜特性研究

从使用再生水的某电厂冷却塔粘泥中分离出一株具有硫酸盐还原功能的弗氏柠檬酸杆菌.利用扫描电子显微镜（SEM）和能谱仪（EDS）对再生水中HSn70-1A和BFe30-1-1两种合金表面弗氏柠檬酸杆菌生物膜结构和成分进行表征,结果表明HSn70-1A成膜特性好于BFe30-1-1,两种合金表面生物膜中C、O等无机元素含量较...     

没食子酸丙酯对K562细胞的增殖抑制和诱导凋亡作用

观察没食子酸丙酯(Propyl gallate,PG)对人慢性髓系白血病K562细胞株的增殖抑制及诱导凋亡作用.采用倒置显微镜观察细胞形态及数目的变化,乳酸脱氢酶(Lactate dehydrogenase,LDH)释放检测细胞活性,流式细胞术PI染色法及DNA倍体分析检测细胞凋亡作用.结果表明,没食子酸丙酯能有效地抑制K562细胞增殖,药物处理24 h时细胞形态发生变化,细胞数目减少;细胞培养液中LDH活性分析显示,20~300μg/mL没食子酸丙酯处理24 h对细胞毒性作用不明显;但处理时间达48 h时,没食子酸丙酯对细胞毒性明显增加;亚二倍体峰(凋亡峰)的出现及DNA片段化分析表明,200μg/mL PG处理细胞24 h时,能引起K562细胞凋亡.结果表明,PG具有明显的体外抗肿瘤活性,其抗癌活性与其抑制细胞增殖、诱导细胞凋亡有关.图5参18     

反应条件对苛求芽孢杆菌胞内尿酸酶与嘌呤衍生物作用的影响

用底物尿酸的紫外吸收变化跟踪反应,用单或双底物米氏方程和初速度估算苛求芽孢杆菌胞内尿酸酶最大反应速度,按Arrenius经验公式得到该尿酸酶在pH 9.2和pH 7.4的活化能,但这些活化不能解释其在两个pH下的催化活性差异.该酶同常见嘌呤衍生物氧嗪酸、黄嘌呤和尿酸有亲和力,但对尿酸亲和力最低,且亲和力与嘌呤衍生物解离成阴离子的能力相关.在生理条件下,该酶对尿酸的亲和力相对于最适条件有显著下降.据此推测,优化静电相互作用选择性增强该酶对尿酸的亲和力是提高其成药性的可能措施之一.     

一株高浸磷嗜酸氧化硫硫杆菌的分离与鉴定

从矿山土样中分离到一株嗜酸的浸磷矿细菌HY-01,观察其形态并研究其培养特征.结果显示,该菌株为革兰氏阴性、短杆状运动细菌,菌体长1～2μm,宽0.5～0.7 μm,能在pH 1.5～8.0的范围内生长,最适生长温度为37℃,最适pH为1.5～3.0.该菌株可以KNO3、NH4NO3、(NH4)2CO3、NH4H2PO...     

水稻OsGPCR基因的克隆及遗传转化分析

G蛋白偶联受体(G protein-coupled receptors,GPCR)基因家族是目前已知最大的膜受体超家族,参与生物的生长发育调控和激素应答.通过RT-PCR分离了水稻中一个具有7次跨膜(Seven transmembrane,7TM)结构域的OsGPCR候选基因;分析该基因启动子序列,发现它含有赤霉素GA应答相关元件.为分析其功能,分别构建OsGPCR过表达和RNA干涉载体,并通过农杆菌介导法转化获得转基因水稻植株.实验结果表明,较之野生型,过表达转基因植株对赤霉素反应更敏感,RNA干涉植株则反之.     

过期牛奶保养木地板——最省钱的保护膜

牛奶过期后,味道会变酸,这会增加牛奶中的乳酸含量。而乳酸是一种天然的去污剂,可以清理木地板。此外,牛奶中所含的蛋白质和脂肪等物质,可以在木地板上形成一层保护膜,不仅让地板光亮如新,而且能保护地板表层不被过多磨损或刮划。牛奶中的油脂擦在地板表面,还有利于地板保持原有的色泽,不易脱色或变色,也不容易让地板变形。     

模拟电镀污泥阴离子浸出液对氧化亚铁硫杆菌活性的影响

利用课题组分离得到的氧化亚铁硫杆菌WZ-1(GenBank序列登录号:JQ968461)研究电镀污泥浸出液中无机阴离子对WZ-1活性的影响,考察了Cl-、NO-3、F-这3种单一阴离子以及4种不同模拟电镀污泥阴离子浸出液对WZ-1 Fe2+氧化活性和表观呼吸速率的影响,结果表明菌株在接种量为6.7%、初始pH 2.0、温度30℃、转速150 r·min-1的条件下,浓度分别为5.0 g·L-1、1.0 g·L-1的Cl-、NO-3对WZ-1的活性没有影响;WZ-1对Cl-、NO-3、F-的最大耐受浓度分别为10.0 g·L-1、5g·L-1、25.0 mg·L-1;4种模拟电镀污泥阴离子浸出液对WZ-1活性的影响有明显差异,强弱顺序为:Cl-/NO-3/F-≥NO-3/F->Cl-/F->Cl-/NO-3.     

Isolation and characterization of a thermophilic Bacillus shackletonii K5 from a biotrickling filter for the production of polyhydroxybutyrate

Polyhydroxyalkanoates（PHAs） are aliphatic polyesters accumulated intracellularly by both Gram-negative and Gram-positive bacteria. However, compared to the PHAs of Gramnegative bacteria, few endotoxins（lipopolysaccharides, LPS）, which would be co-purified with PHAs and cause immunogenic reactions, are found in the PHAs produced by Gram-positive bacteria. A thermophilic Gram-positive bacterium K5, which exhibited good growth and polyhydroxybutyrate（PHB）-accumulating ability, has been isolated and characterized from a biotrickling filter designed for the removal of NOx from flue gas in a coal-fired power plant in China. Based on the biochemical characterization and 16 S rRNA gene sequence（Genbank accession no. JX437933）, the strain K5 has been identified as Bacillus shackletonii, which has rarely been reported in the literature, and this report is the first time that B. shackletonii has been found to accumulate PHB. The strain K5 was able to utilize glucose as carbon source to synthesize PHB at a broad range of temperatures（from 35 to 50 °C）, and the ideal temperature was 45 °C. The strain K5 could effectively yield PHB of up to 69.9% of its cell dry weight（CDW）（2.28 g/L） in flask experiments employing glucose as carbon source at 45 °C, followed by 56.8% and 52.3% of its CDW when using sodium succinate and glycerol as carbon source, respectively. For batch cultivation, the strain K5 was able to produce PHB of up to 72.6% of its cell dry weight（9.76 g/L） employing glucose as carbon source at 45 °C and pH 7.0.     

Investigation of UV-TiO2 photocatalysis and its mechanism in Bacillus subtilis spore inactivation

The inactivation levels of Bacillus subtilis spores for various disinfection processes （ultraviolet （UV）, TiO2 and UV-TiO2） were compared. The results showed that the inactivation effect of B. subtilis spores by UV treatment alone was far below that for bacteria without endospores. TiO2 alone in the dark, as a control experiment, exhibited almost no inactivation effect. Compared with UV treatment alone, the inactivation effect increased significantly with the addition of TiO2. Increases of the UV irradiance and Ti02 concentration both contributed to the increase of the inactivation effect. Lipid peroxidation was found to be the underlying mechanism of inactivation. Malondialdehyde （MDA）, the degradation product of lipid peroxidation, was used as an index to determine the extent of the reaction. The MDA concentration surged surprisingly to 3.24 nmol/mg dry cell with the combination disinfection for 600 see （0.10 mW/cm2 irradiance and 10 mg/L TiO2）. In contrast, for UV alone or TiO2 in the dark, the MDA concentration was 0.38 and 0.25 nmol/mg dry cell, respectively, under the same conditions. This indicated that both UV and TiO2 were essential for lipid peroxidation. Changes in cell ultrastructure were observed by transmission electron microscopy. The cell membrane was heavily damaged and cellular contents were completely lysed with the UV-TiO2 process, suggesting that lipid peroxidation was the root of the enhancement in inactivation efficiency.