N~+离子诱变高效降酚菌及其含酚废水模拟处理的研究

取降酚效果较好菌株E为诱变出发菌株,利用N+离子束诱变,获得若干突变菌株,计算诱变存活率和正突变率,利用正交实验对离子束诱变的优势菌KE2菌株进行了最适宜生长条件的优化,并进行实验室模拟实验.结果表明诱变注入的较适宜剂量为18.4×1014N+/cm2.诱变菌株中降酚效果最好的诱变菌KE2的降酚率较出发菌E高,且在传代时性状稳定.经初步鉴定,出发菌株E和诱变降酚菌KE2属于假单胞菌(Pseudo-monas.sp.).KE2降酚诱变菌的生长适宜参数为:葡萄糖浓度1 000 mg/L,pH值为7,温度30℃.实验室模拟实验显示,添加诱变菌株的一组降酚效果较好,在500 mg/L的酚浓度下,9 h降酚率可达到100%,1 000 mg/L的酚浓度下,加诱变菌组在12 h可完全降解,达到100%.     

种保素对几种作物根际微生物效应的影响

熹龙种籽保生素(以下简称种保素)为复合营养功能型生物制剂,被列为九五国家级新产品(证书号:5120610060784)。经全国农业技术推广服务中心在全国多个省区几年的试验示范和推广应用,结果在玉米、小麦、棉花、油菜、甜菜、花生等多种作物上拌种施用,能提高发芽率,提早出苗,促进根系发育,叶绿素含量增加,植株生长健壮,具有显著的增产效果1)。作物生长状况与其根际微生物有着非常密切的关系。作物生长期间活跃的新陈代谢作用为根际微生物提供大量的营养物质,产生明显的根际效应,同时根际微生物对根际养分也有显著的活化作用,促进植物的生长发育…     

Genetic and Pathogenic Variation Among Tobacco Black Shank Strains of Phytophthora parasitica var. nicotianae from the Main Tobacco Growing in China

Pathogenic and genetic variability among seven populations of Phytophthora parasitica var. nicotianae from individual tobacco fields (Yunnan, Shandong, Henan, Heilongjiang, Shanxi, Fujian and Sichuan provinces) were investigated using pathogenicity and randomly amplified polymorphic DNA (RAPD) analyses; 63 strains were isolated from different fields of seven tobacco growing regions, using tobacco cv. Hongda as a baiting host. Pathogenic variability was evaluated in greenhouse studies using five tobacco cultivars that have different levels of resistance to tobacco black shank; 75 and 73% of the strains were pathogenic on M3 and M4, 29 and 33% on M1 and M2, and 94% were pathogenic on M5, respectively. Disease severity incited by different strains varied significantly on individual tobacco cultivars. The percentage of strains pathogenic on different cultivars varied among locations. Genotypic variation among 63 strains was evaluated by RAPD analysis. Ten primers detected 89 polymorphic bands. Cluster and principal coordinates analysed cluster groups. the minor group contained 26 strains, and major group contained 37 strains. Estimates of genetic diversity based on RAPD analysis ranged from 0.24 to 0.34 within populations to 0.36 among all strains from all populations. Phytophthora parasitica var. nicotianae populations were genotypically and phenotypically variable, but no distinct genotypic differences were identified among populations from the seven locations.     

不同耕作方式对当归根际土壤细菌群落多样性的影响

该研究以甘肃省中部渭源县大豆—当归轮作地、连作3年的当归地和荒地植物根际土为材料,采用PCR-RFLP法研究不同耕作方式下根际土壤细菌的群落多样性。应用CTAB-SDS法提取土壤微生物总DNA,建立土壤菌群16S rRNA基因克隆文库。用HaeⅢ,HhaⅠ和HinfⅠ对阳性克隆子进行酶切指纹图谱分析,测序并绘制系统进化树。经过初步分析,荒地、轮作地和连作地三者之间根际土壤细菌群落在种群数量和多样性上无显著差异,但在组成结构上存在明显差异,尤其是轮作和连作地。结果表明:轮作地和荒地的优势种群均为变形菌门,连作地的优势种群是拟杆菌门。进一步分析发现,对农作物有利的鞘脂单胞菌属(属于变形菌门)仅在轮作和荒地中出现,而在其他作物连作障碍中出现的无色杆菌属(属于拟杆菌门)仅在当归连作地中出现。因此,不同耕作方式对土壤细菌的群落组成结构影响较明显,土壤细菌群落组成结构的变化可能是当地当归连作障碍的重要原因之一;而轮作可有效提高根际土壤中细菌群落组成的多样性,并使有益细菌种群增加,改善土壤微生态环境,有效防止当归根腐病的发生。     

热泉微生物化石的识别研究及其科学意义

现代海底热液喷口以及许多陆地热泉周围生活着密集的生物群落。热液生态系统的初级生产者嗜热细菌和古细菌(Archaea),其初级能量来源是由地球深部上升喷出流体提供的化学能。围绕现代热泉微生物及其与地史时期热泉微生物化石的对比研究表明,它们具有相似结构特征。研究微生物成矿机制和微生物化石化作用,以及沉积物中由生物化学作用产生的生物标志,不仅有助于探讨海底热液活动的规律性和成矿机制,也可以为鉴别古老岩石和地外矿物中生命现象提供更多更详细的鉴定标志,对于理解生命起源和地外生命都有重要的理论意义。     

利迪链霉菌A02抗真菌活性产物的分离和结构鉴定

利迪链霉菌A02是从京郊森林土壤中分离筛选出的植物病原真菌高效拮抗菌株。为了明确其抑菌活性的物质基础,利用大孔树脂和硅胶吸附柱层析、HPLC循环制备分离等方法,从菌株A02发酵液中分离获得了纯度达99.845%以上的单一组分活性化合物。经紫外光谱、高分辨质谱、红外光谱和核磁共振谱的测定和解析,确定了该活性化合物的分子量为665,分子式为C33H47NO13,化学结构与四烯大环内酯类抗生素纳他霉素相同。这一结果揭示了利迪链霉菌产生抗真菌天然产物的新功能,并为纳他霉素在植物病害生物防治中的应用开拓了新的途径。     

昆虫产卵分泌物的产生方式、成分及功能

产卵是昆虫生活史中的重要阶段。绝大多数昆虫产卵前后都会产生分泌物用于卵的粘着和覆盖, 这些分泌物起到保护卵及初孵幼虫的作用;有些昆虫还通过产卵分泌物对卵进行标记, 进而影响种群、个体间对现有资源的有效利用。产卵分泌物是昆虫进化过程中的一种适应, 一般具有特定的生理和生态学功能, 影响着种群数量的变化。本文阐述了不同昆虫产卵分泌物的产生方式及物理性状, 并对产卵分泌物的组成、功能、分泌器官以及产卵分泌物中微生物的研究进展进行了综述。     

Distribution of pathogenic vibrios and other bacteria in imported frozen shrimps and their decontamination by gamma-irradiation

The distribution of pathogenic vibrios and other bacteria in eight samples of imported frozen shrimps and the effect of irradiation on these bacteria were investigated. Total aerobic bacteria were at 2×10⁴ to 4×10⁶/g. Coliforms consisted mainly ofEnterobacter. No salmonella were detected. A total of 66 isolates, includingVibrio parahaemolyticus, V. mimicus, V. alginolyticus, V. vulnificus, V. fluvialis and a few ofListeria monocytogenes, were obtained. The gamma-radiation dose needed to reduce by 10^–4 the number of vibrio isolates andAeromonas hydrophila was about 3 kGy in frozen shrimps, whereas about 3.5 kGy was required forL. monocytogenes.     

Current and Future Transgenic Whole-Cell Biosensors for Plant Macro- and Micronutrients

From the soil, plants take up macronutrients (calcium, magnesium, nitrogen, phosphorus, potassium, sulfur) and micronutrients (boron, chloride, cobalt, copper, iron, manganese, molybdenum, nickel, selenium, and zinc). In acidic soils, aluminum can interfere with nutrient uptake. There is a need for improved diagnostic tests for these soil-derived minerals that are inexpensive and sensitive, provide spatial and temporal information in plants and soil, and report bioavailable nutrient pools. A transgenic whole-cell biosensor detects a stimulus inside or outside a cell and causes a change in expression of a visible reporter such as green fluorescent protein, and thus can convert an invisible plant nutrient into a visible signal. Common transgenic whole-cell biosensors consist of promoter-reporter fusions, auxotrophs for target analytes that are transformed with constitutively expressed reporters, riboswitches and reporters based on Forster Resonance Energy Transfer (FRET). Here, we review transgenic plant biosensors that have been used to detect macronutrients and micronutrients. As plant-based biosensors are limited by the requirement to introduce and optimize a transgene in every genotype of interest, we also review microbial biosensor cells that have been used to measure plant or soil nutrients by co-inoculation with their respective extracts. Additionally, we review published transgenic whole-cell biosensors from other disciplines that have the potential to measure plant nutrients, with the goal of stimulating the development of these diagnostic technologies. We discuss current limitations and future improvements needed, and the long-term potential of transgenic whole-cell biosensors to inform plant physiology, improve soil nutrient management, and assist in breeding crops with improved nutrient use efficiency.     

氮源受限条件下植物病原真菌氮调控基因表达特性

研究证实植物病害的发生往往是由于植物病原真菌分泌的效应子诱导引起的,在此过程中,调控效应基因表达能够了解病原菌的侵染过程。细胞的营养状况据推测对于效应基因的表达起着重要的作用。已有研究表明在氮胁迫条件下相同效应基因的诱导作用在植株体内和体外是一致的,表明氮源缺乏的环境在植物体进化的早期就已经存在了。文章阐述了在氮受限条件下真菌致病系统中效应基因调控机制及其已经发现的氮调节基因特异性表达研究结果,通过对比几个病原菌中氮调控基因的功能,比较寄主植物体内和体外在氮限制条件下基因的诱导效应,从而揭示出氮的有效性在寄主植物病害发展过程中起到重要作用。