Tree girdling provides insight on the role of labile carbon in nitrogen partitioning between soil microorganisms and adult European beech     

Michael Dannenmann  Judy Simon  Rainer Gasche  Jutta Holst  Ingrid Kögel-Knabner  Helmut Mayer  Rodica Pena  Heinz Rennenberg 《Soil biology & biochemistry》2009,41(8):1622-1631

Nitrogen (N) cycling in terrestrial ecosystems is complex since it involves the closely interwoven processes of both N uptake by plants and microbial turnover of a variety of N metabolites. Major interactions between plants and microorganisms involve competition for the same N species, provision of plant nutrients by microorganisms and labile carbon (C) supply to microorganisms by plants via root exudation. Despite these close links between microbial N metabolism and plant N uptake, only a few studies have tried to overcome isolated views of plant N acquisition or microbial N fluxes. In this study we studied competitive patterns of N fluxes in a mountainous beech forest ecosystem between both plants and microorganisms by reducing rhizodeposition by tree girdling. Besides labile C and N pools in soil, we investigated total microbial biomass in soil, microbial N turnover (N mineralization, nitrification, denitrification, microbial immobilization) as well as microbial community structure using denitrifiers and mycorrhizal fungi as model organisms for important functional groups. Furthermore, plant uptake of organic and inorganic N and N metabolite profiles in roots were determined.Surprisingly plants preferred organic N over inorganic N and nitrate (NO₃⁻) over ammonium (NH₄⁺) in all treatments. Microbial N turnover and microbial biomass were in general negatively correlated to plant N acquisition and plant N pools, thus indicating strong competition for N between plants and free living microorganisms. The abundance of the dominant mycorrhizal fungi Cenococcum geophilum was negatively correlated to total soil microbial biomass but positively correlated to glutamine uptake by beech and amino acid concentration in fine roots indicating a significant role of this mycorrhizal fungus in the acquisition of organic N by beech. Tree girdling in general resulted in a decrease of dissolved organic carbon and total microbial biomass in soil while the abundance of C. geophilum remained unaffected, and N uptake by plants was increased. Overall, the girdling-induced decline of rhizodeposition altered the competitive balance of N partitioning in favour of beech and its most abundant mycorrhizal symbiont and at the expense of heterotrophic N turnover by free living microorganisms in soil. Similar to tree girdling, drought periods followed by intensive drying/rewetting events seemed to have favoured N acquisition by plants at the expense of free living microorganisms.  相似文献   

黄绿木霉菌代谢产物对杨树烂皮病菌抑菌能力的研究   总被引：8，自引：0，他引：8  

孙冬梅  杨谦  宋金柱 《北京林业大学学报》2006,28(1):76-79

该文利用室内实验的方法,研究了黄绿木霉菌代谢产物对杨树烂皮病菌的抑菌能力.黄绿木霉菌代谢产物在经121℃处理25 min后,50%浓度下抑菌作用可高达100%.在pH为3～9范围内该代谢产物的抑菌能力变化不大,说明pH变化对其活性没有影响.在对黄绿木霉菌发酵过程中,利用马铃薯葡萄糖(PD)培养基即可达到有效的抑制杨树烂皮病金黄壳囊孢菌菌丝生长的目的,而且利用马铃薯葡萄糖(PD)培养基发酵3～4 d的黄绿木霉菌代谢产物抑菌效果最好,抑菌中浓度最低,发酵时间过长与过短,均不利于对病原菌的抑制.经黄绿木霉菌代谢产物处理的菌丝电导率与呼吸强度均发生变化,在光学显微镜与透射电镜下观察到病原菌菌丝体发生变化,细胞壁有所改变.   相似文献   

Dietary choline improves growth performance,antioxidant ability and reduces lipid metabolites in practical diet for juvenile Pacific white shrimp,Litopenaeus vannamei     

Bo Shi  Xiaoying Hu  Min Jin  Minghong Xia  Mingming Zhao  Lefei Jiao  Peng Sun  Qicun Zhou 《Aquaculture Nutrition》2021,27(1):39-48

An 8‐week feeding trial was conducted to evaluate the effects of dietary choline levels on growth performance, antioxidant capacity and lipid metabolites in juvenile Pacific white shrimp. Six isonitrogenous and isolipidic diets were formulated to supply 0, 1,000, 2,000, 4,000, 6,000, 10,000 mg/kg choline chloride, and dietary choline levels were analysed to be 1,317 (basal diet), 1,721, 2,336, 3,294, 5,421 and 9,495 mg/kg, respectively. Dietary choline levels significantly influenced percent weight gain (PWG) and protein efficiency ratio (PER), with the highest PWG was observed in shrimp fed the 5,421 mg/kg choline diet. However, there were no significant differences in proximate composition of whole body and muscle. Shrimp fed the diet containing 2,336 mg/kg choline had lower HDL and LDL in haemolymph than those fed the basal diet (1,317 mg/kg diet). Dietary choline prevented the accumulation of free radicals and improved antioxidant capacity by increasing catalase activity and reducing malondialdehyde content. Based on broken‐line regression and quadratic regression analysis between PWG against dietary choline levels, the optimal choline requirements were estimated to be 3,254.1 and 6,488.3 mg/kg for juvenile L. vannamei, respectively.  相似文献   

内生放线菌Fq24的拮抗筛选及其代谢产物生物活性研究   总被引：2，自引：1，他引：1  

王桂莲张姝  刘慧平 《中国农学通报》2011,27(16):190-195

通过对番茄内生放线菌的拮抗筛选和其代谢产物生物活性的研究,为防治番茄灰霉病寻找新的生防菌源,并探索植物内生放线菌的生防机理。从健康番茄植株上分离到9株放线菌。通过平板对峙培养和发酵液抑菌活性测定、筛选对番茄灰霉菌有拮抗作用的菌株。以番茄种子及幼苗生长情况,防御酶活性变化,盆栽试验对其代谢产物的促生作用、抗病诱导作用、防病作用等生物活性进行了研究。结果表明：（1）菌株Fq24对番茄灰霉菌的抑菌圈半径大于10 mm,其发酵液的抑制作用可达到68.4%。（2）中浓度的Fq24发酵液促进根茎的生长,幼苗的干、鲜重及株高最大为对照的168.35%、286.30%和70.79%,均为显著增加。（3）番茄幼苗体内防御酶活性明显提高,POD、SOD活性最大增加为71.3%和62.3%。（4）喷施Fq24发酵液可明显降低灰霉病的发病率,取得82.14%的防效。Fq24是株有拮抗作用的菌株,其代谢产物能显著促进番茄种子和幼苗生长;诱导番茄体内抗性酶活性提高,增加植物抗性;明显降低发病率,防病效果好。  相似文献   

A new fungitoxic metabolite from Spiraea alpina Pall.     

Taiping Hou  Yun Teng  Qiu Sun  Zhiyi Yu 《Fitoterapia》2009

The fungitoxic metabolites of Spiraea alpina Pall. were identified using inhibition of Rhizoctonia solani, Gibberella zeae, Pyricularia oryzea and Exserohilum turcicum as an end-point. The major fungitoxic constituent of S. alpina was a new diacylated sugar, structurally elucidated as 6-O-(3′,4′-dihydroxy-2′-methylenbutyryl)-1-O-trans-cinnamoyl-β-D-glucopyranose. This compound could inhibit at 0.1 mg/ml Rhizoctonia solani and Exserohilum turcicum, 87.6% and 63.2%, respectively.  相似文献   

木霉菌株Td31代谢产物对立枯丝核菌的拮抗作用   总被引：1，自引：0，他引：1  

咸洪泉  李雅华 《沈阳农业大学学报》2009,40(5)

为了明确木霉菌株Td31代谢产物对植物病原真菌的拮抗作用,利用液体深层发酵法发酵木霉菌株Td31,过滤除菌制备代谢产物,采用生长速率法、显微观察法和盆栽试验法,研究了木霉菌株Td31代谢产物对立枯丝核菌的菌抗作用.结果表明:木霉菌株Td31的代谢产物可抑制立枯丝核菌菌丝的生长及菌核形成和萌发.其中以代谢产物稀释1倍处理的抑菌作用最强,菌丝生长抑菌率高达87.7%,并可完全抑制菌核的形成,菌核萌发抑制率为56.7%.随着木霉菌代谢产物浓度的降低其抑菌效果也随之下降,差异极显著.经木霉菌株Td31代谢产物处理的菌丝原生质浓缩、细胞质外溢、空胞化、细胞壁消解、菌丝斛体.盆栽防病试验结果表明,木霉菌株Td31代谢产物浸种可以有效地防治茄子立枯病,用发酵液原液浸种,防病效果可达69.8%.代谢产物浓度越高,防病效果越好.代谢产物经121℃处理20min后,对抑菌活性和防病效果无明显影响,代谢产物中的主要抑菌活性物质可能是耐高温的抗生素.  相似文献   

红曲菌T-DNA插入突变库转化子的特征及代谢产物分析     

徐驰  邵彦春  吴佳佳  叶阳  李利  李琦  陈福生 《华中农业大学学报》2009,28(2)

以农杆菌介导的红曲菌T-DNA插入突变库中8 000多株转化子为材料,通过菌落形态观察,获得230株形态变化显著的突变子,并将其分为7类.在此基础上,分析了14株代表菌株产色素、莫纳可啉K(Mo-nacolin K)、桔霉素和淀粉酶的情况.结果表明:所有供试菌株的产色素能力均低于出发菌株M-7,其中806#和2553#的色价均不到M-7的1/10;10株突变菌株产Monacolin K的能力高于M-7,其中3245#产Monacolin K的能力较M-7提高了近10倍,达到679.25μg/g;1822#产桔霉素(干红曲)能力最高,达60.01 ng/g,是M-7的近30倍,而806#和178#产桔霉素能力较低,在试验条件下未检测到;13株突菌株的淀粉酶活高于M-7,1067#最高约为M-7的20倍,达3 227.10 U/g.  相似文献   

大豆活性肽在肉鸡饲料中应用的研究     

赵贵兴 《饲料博览》2009,(1):1-4

选用180只健康AA肉仔鸡,随机分成6个处理,每个处理6个重复,每个重复5羽。A组为空白对照,B组为添加抗生素（黄霉素5mg·kg^-1）试验组,C、D、E、F组分别为：添加0．2％、0.4％、0．6％、0.8％大豆活性肽（固态,含活性肽40g·kg^-1）的试验组。结果表明：①大豆活性肽可显著提高肉仔鸡日增重和采食量,在提高屠宰率方面也有一定的作用;②大豆活性肽可以降低饲料成本,增加毛利润;③大豆活性肽最适添加量为0．6％,优于使用抗生素（黄霉素5mg·kg^-1）。  相似文献   

生物活性肽的研究进展   总被引：1，自引：0，他引：1  

李维  兰海楠  郭风  赵雪  付志玲  杨艳红  刘禹  吴天成  郑鑫 《中国畜牧兽医》2012,39(10):105-107

生物活性肽属于多功能因子。随着各种生物活性的不断发现,对其生理功能的不断探究,生物活性肽越来越受到人们的关注。作者对不同来源的生物活性肽,依其不同的生理功能进行了综述,以期为生物活性肽的研发提供参考。  相似文献   

超临界萃取技术在海洋水产的应用研究进展     

刘淑集  吴成业  苏永昌  王茵  刘智禹 《福建水产》2013,(5):402-406

超临界萃取技术作为一种新型“绿色”提取分离技术,具有分离效率高、溶解能力强、保持产品生物活性、提高产品提取率和纯度、操作简单等优点.本文介绍了超临界萃取技术的基本原理及特点,综述了该技术在海洋水产生物活性成分提取方面的研究现状,并展望了其在该领域的应用前景.  相似文献