Differences in Soil Properties and Bacterial Communities between the Rhizosphere and Bulk Soil and among Different Production Areas of the Medicinal Plant Fritillaria thunbergii

To explore rhizosphere effects, geographical differences and their effects on the bacterial community associated with the geoherb Fritillaria thunbergii, some physicochemical properties of soil samples (3 sampling sites × 2 habitats (rhizosphere and bulk soil)) were measured and the soil bacterial community detected by PCR-denaturing gradient gel electrophoresis (DGGE). Among the three regions, soil pH varied between 4.48 and 7.73 indicating that F. thunbergii could grow both in acid and slightly alkaline soil. As the authentic Dao-di producing area, Ningbo showed the highest soil quality with the highest content of organic matter (OM) (2.46%), phosphatase (268 mg kg(-1) 24 h(-1)) and urease activity (1481 mg kg(-1) 24 h(-1)). In comparison with the bulk soil, pH, organic carbon content, and phosphatase and urease activities were all lower in the rhizosphere, suggesting that the roots may secrete some unique metabolites in root exudates. Statistical analyses showed that soil properties of Ningbo and Panan in Zhejiang province were more similar to each other than those in Nantong in Jiangsu province. In addition, PCR-DGGE analysis showed that main bacterial population identified in F. thunbergii was proteobacteria (18 bands, 55%), acidobacteria (4, 12%), actinobacteria (4, 12%) and bacterioidetes (6, 18%). Overall, soil properties and microbial communities varied not only between the rhizosphere and bulk soil but also among the three regions. We suggest that the plant, together with the soil properties, cooperatively shape the structure of the rhizosphere bacteria, and that the soil properties have a close relationship with the geoherbalism of F. thunbergii.     

Genetic Diversity and Phylogeny of Antagonistic Bacteria against Phytophthora nicotianae Isolated from Tobacco Rhizosphere

The genetic diversity of antagonistic bacteria from the tobacco rhizosphere was examined by BOXAIR-PCR, 16S-RFLP, 16S rRNA sequence homology and phylogenetic analysis methods. These studies revealed that 4.01% of the 6652 tested had some inhibitory activity against Phytophthora nicotianae. BOXAIR-PCR analysis revealed 35 distinct amplimers aligning at a 91% similarity level, reflecting a high degree of genotypic diversity among the antagonistic bacteria. A total of 25 16S-RFLP patterns were identified representing over 33 species from 17 different genera. Our results also found a significant amount of bacterial diversity among the antagonistic bacteria compared to other published reports. For the first time; Delftia tsuruhatensis, Stenotrophomonas maltophilia, Advenella incenata, Bacillus altitudinis, Kocuria palustris, Bacillus licheniformis, Agrobacterium tumefaciens and Myroides odoratimimus are reported to display antagonistic activity towards Phytophthora nicotianae. Furthermore, the majority (75%) of the isolates assayed for antagonistic activity were Gram-positives compared to only 25% that were Gram-negative bacteria.     

基于SiO2材料的细胞固定化研究及应用

基于SiO2的材料主要由烷氧基与水溶性方法合成：前者主要以TMOS或TEOS为SiO2前躯体,并用其它有机硅化合物,甘油和海藻酸钙等对其进行进行修饰或复合,后者主要以硅酸钠溶液与胶体SiO2为硅源。这种材料可以包埋微生物,植物细胞,动物细胞,包埋后的生物复合材料则成为生物反应器,生物传感器,生物催化剂,人造生物器官等,它们可用于工业化学合成、信号监测、废水处理和细胞治疗。     

光合细菌对土壤中Cd形态分布的影响

研究了光合细菌球形红细菌(Rhodobacter sphaeroides)在不同理化因素下对土壤中重金属镉形态分布的影响.结果表明,该菌株影响土壤中Cd形态分布的最佳条件为:pH 7、温度35℃及加菌量106个/g土.在最佳条件下,光合细菌能最大降低生物可利用性的Cd形态含量和最大提高生物不可利用性的Cd形态含量.因此...     

A/O工艺结合高效菌技术处理焦化废水的中试研究

将自行研发的高效菌投加于武钢焦化公司A/O中试装置中,进行生物强化研究。研究结果表明,系统有机物和氨氮去除效果优异,CODcr和氨氮的去除率最高可分别达到95%和97%以上,出水CODcr和氨氮均达到国家一级排放标准。在无需外加碳源的情况下,缺氧池反硝化良好,反硝化率达到50%~73%,缺氧池CODcr脱除率可达到20%~45%。     

不同污水除磷工艺中α一变形杆菌群落结构的分析

采用PCR-DGGE技术研究了正常运行工况下4个不同污水除磷系统中α-变形杆菌的菌落结构.研究表明,α-变形杆菌对处理水水质和工艺要求不高,共有菌种几乎均为优势菌种,构成系统的主体除磷菌群.但是总体来看,不同的污水处理系统的差异性比较明显,MBR工艺比传统活性污泥工艺菌群丰富,同时可能是由于存在特有菌种,MBR系统的多...     

拮抗油菜菌核病的海洋细菌筛选及其活性物质的分子检测

以油菜核盘菌为病原指示菌,对1021株海洋细菌进行抗菌筛选,从中得到了144株具抗菌活性的菌株.在建立筛选新型特异性拮抗化合物资源库的同时,重点分析了筛选的302株海洋假单胞菌,对其中具有较强抗菌活性的19株假单胞菌进行了产活性物质合成基因的分子检测.结果表明,菌株1A06832和SH-46扩增获得了2,4-二乙酰基间...     

微生物降解含聚污水的研究进展

主要介绍了微生物降解聚丙烯酰胺的优势、机理,讨论了微生物降解聚丙烯酰胺的影响因素,综述了微生物降解聚丙烯酰胺的国内外研究进展,指出了其在实际应用中存在的不足.     

维生素B12的技术进展

维生素B12是人和动物体内霞要的水溶性维生素之一。综述了维生素B12的性质、合成及生产情况。工业生产中,脱氮假单胞杆菌和费氏丙酸杆菌是主要的生产菌种,有厌氧和好氧2种生产工艺。今后应培养高产菌株,改进发酵工艺。