添海发现原始细菌

近日,日本渔民岩田正春,在常滑市近海的伊势湾捕获了一条腰围有手腕粗,长1.1米,重2.9公斤的特大“海鳗”,并送到名古屋水族馆进行展出。鳗鱼一般出生在海洋,在河流、湖泊生活5年～10年后,再返回海洋产卵。但据名古屋水族馆的专家介     

Effect of Integrated Use of Inorganic Fertilizer and Organic Manures on Bacterial Wilt Incidence （BWI） and Tuber Yield in Potato Production Systems on Hill Slopes of Central Kenya

Bacterial wilt (BW) caused by Ralstonia solanacearum is one of the most damaging diseases of potato (Solarium tuberosum L.) in Kenya and worldwide. In Kenya, potato tuber yield losses due to BW infection are estimated at 50 ～ 100%. Low soil fertility is also one of the most important constraints limiting potato production in central Kenya highlands. Farmers tackle this problem through use of inorganic fertilisers and organic manures, both of which amend the soil environment to influence bacterial wilt development. Undecomposed organic manures can also introduce the pathogen into a clean field. Between short rains 1999 and 2000, 10 on-farm extension-researcher-farmer-designed and farmer-managed trials were done at Kianjuki catchment in Embu District. The objective was to use farmers‘ participatory research approach and select the most suitable organic and inorganic fertiliser combination(s) with lowest BWI and acceptable usable tuber yields, and also to demonstrate use of some components of integrated disease management methods in reduction of disease incidence and spread. Seven treatments were proposed, presented to the farmers for discussion and the most relevant four were selected for evaluation. A newly released potato variety ‘Asante‘ was planted during the short rains 1999 and long rains 2000. BWI didn‘t result in significant differences between treatments but the tuber yields were significantly different in short rains of 1999 and 2000. During short rains 2000, both BWI and tuber yields and unusable tubers differed significantly between treatments. The results confirmed that well-decomposed manures or manures from pathogen-free areas can be used in combination with inorganic fertilisers to improve soil fertility and potato tuber yields in smallholder farms without influencing BWI. Use of certified seed tubers in pathogen free field and following recommended field sanitation measures resulted in apparently bacterial wilt free crop. Considering the high cost of inorganic ferfiliser and its negative effects on the environment, reduced usage at half the recommended rates combined with half rates of FYM is feasible option friendly to the farmer, soil and environment. The interviewed farmers also ranked the option as the most appropriate combination for soil fertility improvement for potato production in smallholder farms.     

Effect of enclosure and nutrient enrichment on Microcystis blooms in Donghu Lake

1 INTRODUCTION Surface blooms of nuisance cyanobacteria are often a signal of eutrophication (Jacoby et al., 2000). They are generally favored by conditions of low nitrogen to phosphorus ratios, high total phosphorus content, high water temperature, high …     

漂白粉消毒后对虾养殖源水细菌群落的响应特征研究

漂白粉消毒是凡纳滨对虾养殖源水常见的管控措施, 可有效控制病原菌传播; 然而,消毒会强烈扰动水体微生物群落,但源水细菌群落对漂白粉消毒的响应特征尚未阐明。在室内条件下, 设置高浓度(60 mg/L)和低浓度(20 mg/L)漂白粉消毒源水, 通过高通量测序及荧光定量PCR技术探究消毒后源水细菌群落、病原菌及抗生素抗性基因(ARGs)的动态响应规律。结果显示, 消毒后, 拟杆菌门(Bacteroidota)丰度上升, 高浓度组变形菌门(Proteobacteria)的丰度显著降低; 至第3天, 两组源水的细菌群落组成趋于一致。此外, 漂白粉消毒显著改变了源水的细菌群落结构及共现网络的复杂性。在控制水体病原菌方面, 消毒后病原菌的总丰度降低, 但种类增加, 高浓度漂白粉消毒对病原菌的抑制作用更加显著。漂白粉消毒对ARGs的去除具有选择性, 仅对sul1、floR、cfr、tetQ有一定的去除作用, 且高、低浓度对ARGs的去除无差异。综上, 60 mg/L可以作为漂白粉消毒养殖源水的更好浓度选择。研究结果从微生物生态视角评价了不同浓度漂白粉的消毒作用, 可为对虾养殖生产中的源水管控提供理论支撑。     

Isolation of novel psychrophilic bacteria from Arctic sea ice

The phylogenetic diversity of cuhurable psychrophilic bacteria associated with sea ice from the high latitude regions of Canadian Basin and Chukchi Sea, Arctic, was investigated. A total of 34 psychropilic strains were isolated using three methods of （ Ⅰ ） dilution plating （ at 4 ℃ ）, （ Ⅱ ） bath culturing （ at - 1 ℃ ） and dilution plating, and （ Ⅲ） cold shock （ -20 ℃ for 24 h）, bath culturing and dilution plating under aerobic conditions. Sea-ice samples were exposed to -20 ℃ for 24 h that might reduce the number of common microorganisms and encourage outgrowth of psyehrophilic strains. This process might be able to be introduced to isolation psychrophilic bacteria from other environmental samples in future study. 16S rDNA nearly full-length sequence analysis revealed that psychrophilic strains felled in two phylo- genetic divisions, γ-proteobacteria （in the genera ColweUia,Marinobaeter、Shewanella,Glaciecola,Marinomortas and Pseudoalteromortas ） and Cytophaga-Flexibacter-Baeteroides （ Flavobacterlum and Psyehroflexus）. Fifteen of bacterial isolates quite likely represented novel species （16S rDNA sequence similarity below 98% ）. One of strains （BSi20002） from Canadian Basin showed 100% sequence similarity to that of Marinobacter sp. ANT8277 isolated from the Antarctic Weddell sea ice, suggesting bacteria may have a bipolar distribution at the species level.     

冰层下的产烷生物——科学家在格陵兰岛冰层下发现可能与火星地表下同样的微生物

加利福尼亚大学伯克利分校的科学家正在进行一项研究，对象是一种能制造甲烷气体的细菌。这种细菌生活在格陵兰岛足有3．2千米厚的冰层底层。这项研究能够帮助科学家去探索火星上类似的微生物。     

天然水体中生物膜对水环境中磷的生物地球化学过程影响

介绍了生物膜及其发育形成机理,生源要素磷与底泥、悬浮颗粒、藻类及细菌之间的相互作用,生物膜中微生物对生源要素磷循环的作用及其检测方法。通过对该领域近几年最新研究成果的总结,得出生物膜尤其是细菌对元素磷迁移转化的影响起着重要作用;对今后研究重点作出展望,在考虑生物膜存在的条件下,深入研究沉积物、悬浮颗粒、藻类及细菌与磷循环的相互作用机制,将有助于弄清楚水体富营养化发生的过程及机理。     

养殖场底泥中芽孢杆菌属细菌的生态学研究

对近海养殖场底泥细菌的研究，发现养殖池底泥中芽孢菌为优势菌群。应用形态学、生理生化和16S rDNA序列测定，对芽孢杆菌属细菌做进一步分类的结果表明，该属细菌在底泥中的主要种群为蜡状芽孢杆菌、巨大芽孢杆菌、短小芽孢杆菌、坚强芽孢杆菌、Bacillus baekryungensis等。同时，还分析了这些芽孢杆菌属细菌在底泥元素的地球化学循环中的作用，认为这类细菌应属于陆生微生物，在养殖环境中代谢有机化合物产生氨、亚硝酸盐和H2S，对养殖环境产生不利的作用和影响。     

四川南江坪河碱性岩体岩石学特征及成因

碱性岩在地表出露很少,主要分布于大陆内部稳定区和裂谷区以及大洋盆地以内,虽然分布较少,但它们与稀有、稀土及放射性元素关系密切,近来还发现了金、铂等贵金属矿产,越来越引起人们的重视。碱性岩的组成矿物常有斜长石、碱性长石、深色矿物特别是碱性深色矿物和似长石等,其按照SiO2的含量可以分为超基性碱性岩(霓霞岩     

海洋源拮抗细菌的分离、筛选及1株拮抗芽孢杆菌的鉴定

对来自于不同海域的红树树皮、海苔(海洋生物样)和海泥(海洋底质)样品进行细菌分离,并采用管碟法测试了分离出的海洋细菌对金黄色葡萄球菌Staphylococcus aureus、枯草芽孢杆菌Bacillus subtilis、大肠杆菌Escherichia coli、白色念珠菌Candida albicans、黑曲霉As...