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31.
甜菜褐斑病内生拮抗菌的筛选、鉴定及其防效测定 总被引:1,自引:0,他引:1
Three hundred and one endophytic bacteria strains were isolated from healthy sugar beet plants in severely diseased plots in Changji County,Xinjiang Province.Three endophytic bacteria strains,1-5,4-1 and 4-3,showed relatively strong antagonistic against Cercospora beticola.Strain 1-5 was identified as Paenibacillus polymyxa,while strains 4-1 and 4-3 were as Bacillus flexus and Stenotrophomonas sp. by their morphological,physiological and biochemical characteristics.The results from several experiment trials showed that the endophytic bacteria could reduce the disease incidence of sugar beet.The control efficiency reached from 67.6% to 80.2%, indicating that biocontrol with endophytic bacteria was an alternative and potential method to control sugar beet fungi disease. 相似文献
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Despite the importance of the rhizosphere for nutrient turnover, little is known about the spatial patterns of organic phosphorus mineralization by plants and by microorganisms in the rhizosphere. Therefore, the distribution of acid and alkaline phosphatase activity and the abundance of bacteria belonging to various bacterial phyla were investigated in the rhizosphere of barley (Hordeum vulgare L.) as dependent on the availability of inorganic P. For this purpose, we conducted a greenhouse experiment with barley growing in inclined boxes that can be opened to the bottom side (rhizoboxes), and applied soil zymography and fluorescence-in situ-hybridization (FISH). Acid phosphatase activity was strongly associated with the root and was highest at the root tips. Due to P fertilization, acid phosphatase activity decreased in the bulk soil, and less strongly in the rhizosphere. Alkaline phosphatase activity, i.e., microbial phosphatase activity was high throughout the soil in the control treatment and was reduced due to inorganic P fertilization especially in the rhizosphere and less strongly in the bulk soil. P-fertilization slightly increased the total number of bacteria in the rhizosphere. Moreover, P-fertilization decreased the abundance of Firmicutes and increased the abundances of Beta- and Gamma-Proteobacteria. The total number of bacterial cells was significantly higher at the root surface than at the root tip and at a distance of 30 μm from the root surface. Our results show that alkaline phosphatase activity decreased more strongly in the rhizosphere than in the bulk soil due to P fertilization, which might be because of greater C deficiency in the bulk soil compared to the rhizosphere. Furthermore, the results indicate a spatial separation between hotspots of acid phosphatase activity and hotspots of bacteria in the rhizosphere of H. vulgare. Taken together, our study shows that bacteria and phosphatase activity were very heterogeneously distributed in soil, and that the effects of P fertilization on phosphatase activity differed strongly between bulk soil and rhizosphere as well as between various zones of the rhizosphere. 相似文献
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为进一步探讨关中奶山羊乳房炎感染病原菌的情况,对富平县三个不同乡镇的79头患病奶山羊,共118份奶样进行分离鉴定,共分离出7种共126个菌株.其中大肠杆菌36株,占28.5%;金黄色葡萄球菌28株,占22.2%;绿脓杆菌23株,占18.3%;链球菌21株,占16.7%;变形杆菌8株,占6.3%;蜡样芽孢杆菌6株,占4.8%;酵母菌4株,占3.2%.认为该研究区域的关中奶山羊乳房炎主要是由大肠杆菌,金黄色葡萄球菌、绿脓杆菌、链球菌所致. 相似文献
35.
Effects of concentrate‐to‐forage ratios and 2‐methylbutyrate supplementation on ruminal fermentation,bacteria abundance and urinary excretion of purine derivatives in Chinese Simmental steers 下载免费PDF全文
C. Wang Q. Liu G. Guo W. J. Huo C. X. Pei S. L. Zhang H. Wang 《Journal of animal physiology and animal nutrition》2018,102(4):901-909
This study evaluated the effects of dietary concentrate levels and 2‐methylbutyrate (2MB ) supplementation on performance, ruminal fermentation, bacteria abundance, microbial enzyme activity and urinary excretion of purine derivatives (PD ) in steers. Eight ruminally cannulated Simmental steers (12 months of age; 389 ± 3.7 kg of body weight) were used in a replicated 4 × 4 Latin square design with a 2 × 2 factorial arrangement. Moderate‐concentrate (400 g/kg diet [MC ]) or high‐concentrate (600 g/kg diet [HC ]) diets were fed with or without 2MB (0 g/day [2MB ?] or 15.0 g/day [2MB +]). Dry matter intake and average daily gain increased, but feed conversion ratio decreased with the HC diet or 2MB supplementation. Ruminal pH decreased, but total volatile fatty acid increased with the HC diet or 2MB supplementation. Molar proportion of acetate and acetate‐to‐propionate ratio decreased with the HC diet, but increased with 2MB supplementation. Propionate molar proportion and ruminal NH 3‐N content increased with the HC diet, but decreased with 2MB supplementation. Neutral detergent fibre degradability decreased with the HC diet, but increased with 2MB supplementation. Crude protein degradability increased with the HC diet or 2MB supplementation. Abundance of Ruminococcus albus , Ruminococcus flavefaciens , Fibrobacter succinogenes and Bufyrivibrio fibrisolvens as well as activities of carboxymethyl cellulase, cellobiase, xylanase and pectinase decreased with the HC diet, but increased with 2MB supplementation. However, abundance of Prevotella ruminicola and Ruminobacter amylophilus as well as activities of α‐amylase and protease increased with the HC diet or 2MB supplementation. Total PD excretion also increased with the HC diet or 2MB supplementation. The results suggested that growth performance, ruminal fermentation, CP degradability and total PD excretion increased with increasing dietary concentrate level from 40% to 60% or 2MB supplementation. The observed diet × 2MB interaction indicated that supplementation of 2MB was more efficacious for improving growth performance, ruminal fermentation and total PD excretion with promoted ruminal bacteria abundance and enzyme activity in the MC diet than in the HC diet. 相似文献
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鸭源致病性大肠杆菌的血清型鉴定及其相关毒力基因分析 总被引:2,自引:0,他引:2
自规模化养鸭场患典型大肠杆菌败血症雏鸭分离的282株致病性大肠杆菌(E.coli)中鉴定出210株(包含37种血清型),其中O93、O78、O92、O76占43.8%(92/210)为优势血清型,O46、O32&O93混合型、O60&O93混合型为首次从鸭群中分离到。应用PCR结合核酸序列测定对210株致病性E.coli(鸭大肠杆菌病分离株)和28株自健康雏鸭泄殖腔拭子分离的E.coli(临床健康鸭大肠杆菌分离株)进行包括强毒力岛(HPI)中的鼠疫菌素受体基因(fyuA)和铁调节蛋白基因(irp2)、Ⅰ型菌毛必需蛋白基因(fimC)、P型菌毛结构基因(papA)和血清耐受基因(iss)检测,结果表明:fyuAi、rp2、fimC、papA和iss基因在鸭大肠杆菌病分离株的携带率分别为41.0%、43.3%、92.9%、97.6%和96.7%,在临床健康鸭大肠杆菌分离株的携带率分别为21.4%、25.0%、92.9%、100%和92.9%,患病鸭和临床健康鸭大肠杆菌分离株iss、fimC和papA携带率差异不显著(P〉0.05),但papA的携带率均显著高于其他宿主(鸡、猪和人)源E.coli;HPI毒力岛在鸭源E.coli中分布较广,其携带率表现为鸭大肠杆菌病分离株极显著高于临床健康鸭大肠杆菌分离株。HPI毒力岛的携带率与菌株的致病性呈明显的正相关,与O78等特定的血清型有一定的关系。鸭大肠杆菌病分离株有37.6%(79/210)同时携带fyuAi、rp2、fimCi、ss和papA基因,极显著高于健康鸭大肠杆菌分离株的14.3%(4/28)(P〈0.01)。 相似文献
38.
银杏内生细菌防治辣椒疫病研究 总被引:1,自引:0,他引:1
从健康银杏植株叶片中分离到108 株内生细菌,通过平板测试从中筛选获得35 株对辣椒疫霉菌Phytophthora capsici具有拮抗作用的菌株.温室盆栽试验证明,菌株 Zy44、Fy11、Hy7、Hy14 和 Zy25 对辣椒疫病防效显著,其中Zy44 和 Fy11 发酵液在辣椒疫霉菌接种 20 d 后防效分别为 62%和 52.33%;经形态观察、生理生化特征测试、16S rDNA序列和gyrB基因序列分析,鉴定这两个菌株为解淀粉芽胞杆菌Bacillus amyloliquefaciens;其发酵滤液及酸沉淀获得的脂肽类抑菌物质对盆栽辣椒苗疫病的防治试验结果表明,菌株 Zy44 的防效高于 Fy11,且脂肽类物质的防效高于发酵滤液;显微镜观察发现菌株 Zy44的脂肽类抑菌物质可导致辣椒疫霉菌菌丝体膨大, 分枝增多, 成簇状,并显著抑制孢子囊的形成. 相似文献
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