Localization of bacteria in lichens from Alpine soil crusts by fluorescence in situ hybridization

Lichens are prominent components of many biological soil crusts. Owing to their persistence, lichen thalli create microhabitats for other microbes. Here, the structure of bacterial communities at the thallus–soil interface in lichen soil crusts was studied by using fluorescence in situ hybridization (FISH), confocal laser scanning microscopy (CLSM) and 3D image reconstruction. Terricolous lichen thalli above the tree-line in open habitats of the Austrian Alps were sampled. We selected six lichen species associated with green algal photobionts: Arthrorhaphis citrinella, Baeomyces placophyllus, B. rufus, Icmadophila ericetorum, Psora decipiens and Trapeliopsis granulosa. Alphaproteobacteria and Acidobacteria are predominant in these soil crust lichens, where the latter are frequently present in the lower part of lichen thalli and in the hypothallosphere. In the inconspicuous thallus structures of Arthrorhaphis citrinella, Baeomyces rufus, Icmadophila ericetorum and Trapeliopsis granulosa we observed association of bacteria with algal cells in soil particles and on the outer surface of the mycobiont–photobiont aggregates. We found bacterial cells intermixed with photobiont cells in the lower part of the lichen thalli and as small colonies on the surface of the squamules of Baeomyces placophyllus and Psora decipiens. Moreover, technical issues of performing FISH and confocal microscopy with biological soil crusts are discussed.     

条斑紫菜(Pyropia yezoensis)绿斑病病原菌的分离鉴定

绿斑病(Green spot disease)是一种常见的海区栽培条斑紫菜(Pyropia yezoensis)病害，在整个紫菜栽培期间都可能发生，以每年11~12月份最为严重，主要出现在幼叶期和成叶期。首先，在叶状体上出现红色或淡红色小斑，而后逐渐转变为绿色，病斑继续扩展，在叶状体表面形成若干孔洞，后期几乎整个藻体变绿。本研究对日照地区患绿斑病的条斑紫菜进行病原菌分离纯化，得到5株优势菌(编号为Y1~Y5)，人工回感实验结果显示，Y1可以引起健康条斑紫菜发生绿斑病。对Y1进行了生理生化检测、16S rRNA、dnaA和dnaN基因序列分析，确定病原菌为海洋假交替单胞菌(Pseudoalteromonas marina)。对绿斑病的发病进程进行了观察，并检测了培养温度、海水比重和养殖密度等环境因子对绿斑病发生的影响，结果显示，高温和高密度养殖会加速绿斑病病情的发展，海水比重为1.022时，绿斑病发病较严重。本研究确定了一株引起条斑紫菜绿斑病的病原菌，并分析了部分理化因子对感染的影响，为条斑紫菜绿斑病的防控提供了基础数据。     

延边黄牛气肿疽间接ELISA诊断方法的建立

[目的]检测延边黄牛气肿疽病原体,为牛气肿疽的检测提供科学方法和依据。[方法]采用气肿疽梭菌裂解菌体为抗原,建立检测该病原菌的酶联免疫吸附检测方法,确定其最适工作条件。[结果]气肿疽梭菌菌体裂解抗原最适包被浓度为50μg/m l;待检血清的最适稀释度为1∶200,酶标二抗的最适工作浓度为1∶2 000;对随机采集于延边地区的30份牛血清样品进行间接ELISA检测,阳性率为20%。[结论]建立的间接ELISA方法特异性和重复性好。     

农药助剂对短短小芽孢杆菌TW-2菌体及芽孢的影响

采用平皿计数法和抑菌圈法研究了24种农药助剂对稻瘟病生防菌短短小芽孢杆菌TW-2菌株菌体和芽孢存活的影响.结果表明,供试的24种农药助剂中有11种农药助剂(D425、D450、D500、EFW、500、505、507、AEO-5、AEO0、NP-10、OP-10)在供试浓度范围内(12.5～100g· L-1)可以完全杀灭短短小芽孢杆菌TW-2菌株的菌体和芽孢,其它助剂随着浓度的提高,对菌体和芽孢存活的抑制作用也越大.在24种农药助剂中,U-3A和By-110对菌体和芽孢的存活影响最小,可用于短短小芽孢杆菌TW-2菌株固体制剂和液体制剂加工中的湿润展布剂.