2,4-二乙酰基藤黄酚产生菌在番茄根部的定殖及对番茄青枯病的防治

2,4-二乙酰基藤黄酚(2,4-DAPG)产生菌是荧光菌对土传病害进行生物防治的主要类群之一。室内筛选结果表明：供试的12个2,4-DAPG产生菌菌株对番茄青枯病菌均有不同程度的抑制作用,其中CPF、10抑菌效果最佳,抑菌带宽为3．5mm;而2P24、5J10次之,抑菌带宽为3．0mm。CPF10和2P24培养原液对番茄胚根的生长均有明显的抑制作用。CPF10和2P24根部定殖结果表明,两菌株均可在番茄幼苗根部大量定殖,根表细菌数量随着时间延长呈下降趋势但仍维持较高数量;而根内细菌数量有明显上升的趋势。CPF10和2P24对番茄青枯病均有一定的防治效果,其中2P24的防治效果最好。而CPF10在所有的处理中变异系数(CV)最小,防治效果最稳定。     

沼泽红假单胞菌的抗氧化酶活性和对紫外线的吸收作用

对不同培养方式下沼泽红假单胞菌的5个菌株的菌体的抗氧化酶活性以及培养液的细胞和上清液对紫外线吸收作用进行了研究。结果表明,5个菌株的活细胞CAT活性普遍以好氧黑暗条件下的培养物高于微好氧光照条件下的,SOD活性则以微好氧光照条件下的培养物高于好氧黑暗条件的。5个菌株在好氧黑暗、微好氧光照培养条件下的细胞液和培养液的上清液在紫外线200～300nm波长范围有明显的吸收峰。     

Effects of substrate sterilization,fungicide treatment,and mycorrhization helper bacteria on ectomycorrhizal formation of pedunculate oak (Quercus robur) inoculated with Laccaria laccata in two peat bare-root nurseries

Summary Pedunculate oak seedlings (Quercus robur) inoculated with the ectomycorrhizal fungus Laccaria lacata were grown for 1 year on fertilized sphagnum peat in two nurseries. Three factors affecting microbial populations in the substrate were studied, fungicide treatment of the seeds, peat disinfection before sowing (methyl bromide or steam pasteurization), and inoculation with mycorrhization helper bacteria. Treatment of acorns with Iprodione had no depressive effect on mycorrhiza formation. Both disinfection techniques were equivalent, stimulating or depressing mycorrhiza formation depending on the initial microflora in the peat. The introduction of two previously selected mycorrhization helper bacteria (one Pseudomonas fluorescens and one unidentified fluorescent pseudomonad), isolated from L. laccata sporocarps associated with Douglas fir—L. laccata ectomycorrhizas in other nurseries, significantly increased the mycorrhizal rate from 30 to 53% of the short roots. The implications of these results for the controlled mycorrhization of planting stocks and the specificity of mycorrhization helper bacteria are discussed.     

Microbial populations,enzyme activities and nitrogen-phosphorus-potassium enrichment in earthworm casts and in the surrounding soil of a pineapple plantation

Summary Total populations of bacteria and fungi, dehydrogenase activity (as a measure of total potential microbial activity), and urease and phosphatase activities were determined in earthworm casts and surrounding laterite soils planted to pineapple. The casts contained higher microbial populations and enzyme activities than the soil. Except for fungal populations, statistically significant (P = 0.05) increases were found in all other parameters. Microbial populations and enzyme activities showed similar temporal trends with higher values in spring and summer and lower values in winter. The earthworm casts contained higher amounts of N, P, K and organic C than the soil (P = 0.05). Selective feeding by earthworms on organically rich substrates, which break down during passage through the gut, is likely to be responsible for the higher microbial populations and greater enzyme activity in the casts.     

Fungal biomass in pastures increases with age and reduced N input

Previous studies have shown that soil fungal biomass increases towards more natural, mature systems. Shifts to a fungal-based soil food web have previously been observed with abandonment of agricultural fields and extensification of agriculture. In a previous field experiment we found increased fungal biomass with reduced N fertilisation. Here, we explore relationships between fungi, bacteria, N input and grassland age on real dairy farms in the Netherlands. We hypothesised that also in pastures that are still in production there is a negative relationship between fungal biomass and fertilisation, and that fungal biomass increases with grassland age in pastures that are still in production. We expected the fungal/bacterial biomass ratio to show the same responses, as this ratio has often been used as an indicator for management changes. We sampled 48 pastures from eight organic dairy farms. Sites differed in age and fertilisation rate. We determined fungal and bacterial biomass, as well as ergosterol (a fungal biomarker). Fungal and bacterial biomass and ergosterol, showed a negative relationship with N application rate, and correlated positively with organic matter percentage. In old pastures, fungal biomass and ergosterol were higher than in younger pastures. Because bacterial biomass responded in the same way as fungal biomass, the F/B ratio remained constant, and can therefore—in our data set—not be used as an indicator for changing management. We conclude that the changes in fungal and bacterial biomass were driven by changes in organic matter quality and quantity. The negative relationship we found between N application rate and fungal biomass adds to earlier work and confirms the presence of this relationship in pastures with relatively small differences in management intensities. Earlier studies on shifts in fungal biomass focused on ex-agricultural fields or restoration projects. Here we show that fungal biomass is also higher in older agricultural pastures.     

冀北水稻田土壤细菌群落结构和多样性研究

为探讨冀北水稻田土壤细菌群落结构和多样性,以承德地区水稻主产区（河北隆化,河北滦平）稻田土壤为试验材料,采用高通量测序技术,对水稻大田土壤细菌群落结构和多样性进行研究。结果表明：不同地区水稻田土壤微生物多样性存在差异,其中样本ZYY.CKD9中微生物多样性最高且有益菌较多,主要有硫杆菌属（Thiobacillus）、拟衣藻属（Dechloromonas）和地杆菌属（Geobacter）;但也存在共有细菌菌群,如Kaistobacter、溶杆菌属（Lysobacter）、乳酸杆菌属（Lactobacillus）、Candidatus_Solibacter、硫杆菌属（Thiobacillus）、红长命菌属（Rubrivivax）、拟衣藻属（Dechloromonas）、Anaeromyxobacter、硝化螺旋菌属（Nitrospira）等;PCA分析结果显示,土壤细菌群落结构空间相关性不明显。这为冀北水稻田土壤修复、病害防治及功能菌肥开发,促进水稻高产栽培提供依据。     

鲎C因子的研究进展

鲎C因子是鲎血细胞中一种对内毒素敏感的丝氨酸蛋白酶原,主要有6种结构域,能特异结合内毒素而被激活.对鲎C因子的结构与功能、基因工程研究及其应用前景进行了综述.     

不同温度对扬州盐水鹅品质的影响

[目的]为了保证扬州盐水鹅的卫生质量和品质。[方法]对扬州盐水鹅在不同保存温度下菌落总数、菌相和pH值的变化进行试验性观察。[结果]当菌落总数达到106 cfu/g、腿肌pH值为6.5以上时,均有异味产生;腐败过程中的优势菌种,37℃为肠球菌属和葡萄球菌属,20℃为变形杆菌属,4℃为假单胞菌属;对于当天制作并于中午出售的盐水鹅,其保存期限建议值为:37℃不超过7 h,20℃不超过24 h,4℃不超过6 d。[结论]该研究为建立健全可供盐水鹅新鲜度鉴定使用的卫生评价指标提供了依据。     

大型海藻对海水水族箱生态微宇宙结构及稳定性的影响

稳定高效的多营养层级景观生态系统构建是近年来水族行业的发展热门,为探究海水水族箱在引入大型海藻后微宇宙生态系统结构和稳定性的变化,分别对不同处理组进行水质指标、浮游生物及细菌群落结构分析。结果表明：（1）有藻组水体溶解氧（DO）含量和pH上升趋势高于无藻组,并可维持亚硝态氮（NO2--N）含量在较低水平,实验结束时磷酸盐（PO43--P）及铵态氮（NH4+-N）含量显著低于无藻组（P < 0.05）。（2）有藻组细菌多样性及均匀度指数显著低于无藻组（P < 0.05）;浮游生物群落均匀度指数存在显著组间差异（P < 0.05）。（3）细菌群落结构分析结果显示,无藻及有藻组第一、二优势菌门均为变形菌门（Proteobacteria）、放线菌门（Actinobacteria）,无生物对照组分别为变形菌门和厚壁菌门（Firmicutes）;各处理组浮游生物群落的第一优势门均为硅藻门（Bacillariophyta）,至少占样品中浮游生物群落丰度的40%以上,第一优势属均为直链藻属（Melosira）。（4）CCA结果显示,无藻组微生物优势种丰度与营养盐含量呈正相关关系,与溶解氧（DO）及pH负相关,有藻组则相反。通过以上结果可推测,不同营养层级的微宇宙系统浮游生物及细菌群落组成不同,培养针叶蕨藻（Caulerpa sertularioides）能有效改善生态水族箱水质环境并影响水体微宇宙结构,有利于构建稳定高效并美观的海水景观生态系统。     

连作花生田根际土壤优势细菌的分离和鉴定

采用土壤稀释分离法,从不同连作年限花生根际土壤中分离优势细菌,结合菌株形态特征、培养性状、生理生化特征及16S rDNA序列分析结果,对优势细菌进行鉴定.结果表明,种植过花生及花生连作后,土壤中优势细菌种类发生明显变化,从连作花生田根际土壤中分离鉴定出7种优势细菌,分别为Leifsonia xyli、氯酚节杆菌(Art...