南极菌Pseudoalteromonas sp．S-15-13产胞外多糖的研究及其分子鉴定

本文对影响南极细菌S-15-13生长和胞外多糖产量的主要环境因子进行了研究,同时采用16S rDNA序列分析及系统发育分析方法对其进行了分子鉴定。结果表明：菌株S-15-13最佳产糖条件为：培养时间,56h；培养温度,8℃；碳源,1．0%葡萄糖；NaCl浓度,3．0%；pH,6．0-7．0。16S rDNA序列分析和系统发育分析表明,菌株S-15-13属于假交替单胞菌属(Pseudoaltero- monas)。     

上扬子台地晚震旦世灯影组中葡萄状-雪花状白云岩的成因意义

葡萄状 -雪花状白云岩是白云岩形成之后经淡水淋滤作用而成 ,葡萄内或雪花周围的有机物质不是原生藻 ,而是蓝绿藻经细菌腐解后形成的细菌集合体。该套白云岩的形成与沉积环境关系密切 ,与藻类多少无关。葡萄状白云岩富含有机物质 ,而雪花状白云岩孔洞发育 ,因此葡萄状 -雪花状白云岩既是生油层 ,又是良好的储集层 ,对其重新认识和定位 ,必将为寻找深部油气资源提供极为重要场所     

北极海冰细菌产胞外酶及主要环境因子的初步研究

覆盖在北极海洋上的广阔海冰为其内部生存的微生物群落提供了一个独特的生境。研究表明 ,大量海冰细菌能够分泌产生胞外酶 ,其中产蛋白或脂质水解酶细菌的比例远高于产多糖水解酶的细菌。温度、盐度是直接影响海冰细菌生存与活力的 2个主要环境因子。 76%的产酪蛋白酶海冰细菌为低温菌 ,菌株只能在 <35°C条件下生长 ;而 98%的酪蛋白酶最适作用温度≥ 35°C ,其中 62 %的酶最适作用温度≥ 45°C。几乎所有的产酪蛋白酶海冰细菌都耐盐或嗜盐     

细菌浸铜技术在紫金山铜矿的应用

介绍了生物浸矿技术在紫金山铜矿的应用及在这一过程中发现的一些问题，并提出了有待进一步解决的一些问题。     

总磷作为饮用水生物稳定性控制指标的研究

根据国内提出的控制饮用水生物稳定性的可同化有机碳(AOC)标准,通过配制水样研究了AOC及细菌再生长潜力(BRP)同水中磷含量的关系;同时针对净水工艺试验出水水样,考察了水中的磷同其生物稳定性的关系。结果表明,对于配水水样,在一定的磷浓度范围内,磷是水中细菌生长的限制因子;在净水试验工艺出水水样中添加50μg/L的PO₄3--P后,AOC增加了55%,BRP增加了123%,表明水中磷是其生物稳定性的限制因子。由于常规的净水工艺对水中的磷可以有效去除,把水中总磷(TP)控制在5μg/L内来提高饮用水生物稳定性具有一定的可能性和现实性。     

Biomineralization of Uranium: A Simulated Experiment and Its Significance

A simulated experimental reduction of U^v1 and the synthesis of uraninite by a sulfate-reducing bacteria,Desulfovibrio desulfuricans DSM 642, are first reported. The simulated physicochemical experimental conditions were:35℃, pH=7.0-7.4, corresponding to the environments of formation of the sandstone-hosted interlayer oxidation-zone type uranium deposits in Xinjiang, NW China. Uraninite was formed on the surface of the host bacteria after a one-week‘s incubation. Therefore, sulfate-reducing bacteria, which existed extensively in Jurassic sandstone-producing environments,might have participated in the biomineralization of this uranium deposit. There is an important difference in the orderdisorder of the crystalline structure between the uraninite produced by Desulfovibrio desulfuricans and naturally occurring uraninite. Long time and slow precipitation and growth of uraninite in the geological environment might have resulted in larger uraninite crystals, with uraninite nanocrystals arranged in order, whereas the experimentally produced uraninite is composed of unordered uraninite nanocrystals which, in contrast, result from the short time span of formation and rapid precipitation and growth of uraninite. The discovery has important implications for understanding genetic significance in mineralogy, and also indicates that in-situ bioremediation of U-contaminated environments and use of biotechnology in the treatment of radioactive liquid waste is being contemplated.     

MALBAC技术扩增微生物群落基因组的效率评估

环境样品的低生物量是微生物宏基因组学研究面临的首要挑战,通过基因组扩增技术来满足高通量测序对DNA样品量的需求是最常用的解决策略。MALBAC(Multiple Annealing and Looping Based Amplification Cycles)基因组扩增试剂盒最初为扩增和研究哺乳动物的单细胞基因组而研发。本文中,我们通过人工构建的微生物群落来检测该试剂盒在微生物宏基因组扩增方面的效率和应用可行性。结果表明,每个标准反应中,10 pg的DNA模板量足以满足MALBAC试剂盒对样品扩增的需要。每个标准反应DNA模板用量为10和100 pg时,所扩增DNA样品的基因组覆盖度与原始未扩增样品表现出高度的一致性,证明MALBAC试剂盒扩增效果的高度稳定性和一致性。常用的GenomePlex全基因组扩增试剂盒使我们可以在每个标准反应DNA模板量为100 pg的条件下扩增获得足够的DNA样品,但是结果表明该参照试剂盒无法有效的实现对群落中低丰度细菌菌株基因组的线性扩增。对于MALBAC试剂盒和参照试剂盒而言,在扩增高GC含量的微生物物种基因组DNA方面效率低下。我们的实验结果表明MALBAC试剂盒在高效扩增环境样品宏基因组DNA方面的可行性,但对该试剂盒在扩增环境样品中高GC含量微生物物种方面的适用性存在疑虑。     

Distribution of general aerobic heterotrophic bacteria in sediment core taken from the Canadian basin and the Chukchi Sea

The occurrence percentage and abundance of General Aerobic Hetero- trophic Bacteria （GAB） were determined by using the method of MPN for 182 sub- samples from 10 sediment cores taken from the Canadian basin and the Chukchi Sea at two different culturing temperatures. The results showed that the general occurrence percentage of GAB was quite high, average abundanees of GAB at cultured temperatares of 4℃ and 25℃ were 4.46 ×10^7 and 5.47×10^7 cells·g^-1（wt）, respectively. The highest abundance of GAB occurred at 20 -22 cm section in the sediment. GAB abundances changed among the section of sediments, but there is a trend ： the a-bundances at the middle or lower sections were lower than those at upper section. Cultivation at 25℃ could improve the occurrence percentage and abundances of GAB, which suggests that the increasing of temperature may change the living circum-stances of GAB. The differences of GAB among the latitudes areas indicated that occurrence percentage and abundances of GAB in middle latitude areas were higher than those in the higher or lower latitude areas, and were more obvious at 4℃ than those at 25℃. The GAB abundances in sediment under the shallower water seemed to be low- er than those in sediments under the deeper water and this status was more obvious at 25℃ than that at 4℃.     

二氧化氯控制欧洲鳗细菌性疾病

以二氧化氯作为一种新型的消毒剂和杀菌剂 ,以传统含氯制剂 (如漂白粉、二氯异氰尿酸钠、三氯异氰尿酸 )作为对照 ,比较其在治疗欧洲鳗细菌性疾病及改善养殖水质方面的显著特性 ,其作用活性与环境 (如 p H、温度、氨及有机物 )因子的关系。结果表明 ,二氧化氯 (Cl O2 )对爱德华氏菌、嗜水气单胞菌和柱状屈挠杆菌有很好的杀灭效果 ,能迅速治愈欧洲鳗的赤鳍病和肝肾病 ,且能有效改善养殖水体 ,水中生化需氧量比对照组下降 10 %～ 30 % ,化学耗氧量下降 5% ,溶氧量提高 8%～ 10 %。当二氧化氯体积分数为 8m L/m3时 ,其杀菌率均高达 90 %以上 ,为氯制剂的 1.8倍 ,且活性不受环境因子的影响