荧光假单胞菌对食用菌的促生作用及其机理

从小麦根际分离到1株对食用菌有较强促生作用的荧光假单胞菌,命名为假单胞菌P2-10(Pseudomonas sp.P2-10)。该菌株与平菇天达300(Pleurotus ostreatus Td 300)、杏鲍菇杏6(Pleurotus eryngii X6)或鸡腿菇瑞7(Coprinus comatus R7)混合培养,可显著提高这些食用菌菌丝生长速度及诱导并促进子实体的形成和发育。假单胞菌P2-10对食用菌的促生作用来自其代谢产物,可能是通过其1-氨基环丙烷-1-羧酸(ACC)脱氨酶降解食用菌产生的ACC、减少食用菌乙烯的合成及乙烯对菌丝生长和子实体发育的抑制作用。     

油松菌根促生细菌——荧光假单胞菌的分离与鉴定

为了探讨菌根促生细菌荧光假单胞菌(Pseudomonas fluorescens)与菌根真菌的互作关系,本实验从油松菌根上分离得到36株在紫外灯下产荧光的细菌菌株,以荧光假单胞菌9702作为标准菌株,对分离菌株进行显微观察、生物学鉴定和16S rDNA序列分析,结果确定HDY-8、HDY-9、HDY-20、HDY-35共 4株菌株为荧光假单胞菌,并分别命名为P.fluorescens HDY-8、P.fluorescens HDY-9、P.fluorescens HDY-20、P.fluorescens HDY-35.用这4株细菌菌株分别与外生菌根真菌(ECMF)粘盖牛肝菌(Suillus bovinus)、褐环粘盖牛肝菌(Suillus luteus)和褐黄牛肝菌(Boletus luridus)进行纯培养互作研究.结果表明,只有P.fluorescens HDY-20对3种外生菌根真菌有不同程度的促生作用,并对S.luteus促进效果最好,S.bovinus次之,B.luridus最差;P.fluorescens HDY-20促进S.bovinus、S.luteus和B.luridus菌丝生长的最佳浓度分别为2.4×109 cfu/mL、0.8×109～2.4×109 cfu/mL和0.8×109 cfu/mL,与对照相比S.bovinus和S.luteus的生物量达到极显著差异(P<0.01),B.luridus的达到显著差异(P<0.05),且分别比对照增加6.5%、9.1%和4.3%.     

荧光假单胞菌的条件致病性

作者从血、尿标本中分离出12株荧光假单胞菌,在研究生物学性状的基础上探讨了本菌的条件致病性问题,结果显示,凡能使机体免疫力下降的各种原因均可导致本菌感染。治疗本菌感染,必须进行药敏试验,选择有效的抗生素。     

假单胞菌T1-3-2的抑菌特性及其对杉木的抗病促生作用

【背景】生物防治是“基于自然的解决方案”,有利于生态文明和可持续发展,开展生物防治技术研究的基础是明确菌株的生防作用和抑菌特性。【目的】探究杉木内生菌株T1-3-2的抑菌促生特性,为研制该菌株生防菌剂、防治杉木炭疽病(Cunninghamia lanceolata anthracnose)奠定基础。【方法】通过形态学特征、生理生化特性及16S rRNA基因序列分析,确定菌株T1-3-2的分类地位;通过平板对峙、菌落径向生长抑制率和平板倒扣等方法测定细菌及其挥发性气体和次级代谢产物的抑菌作用;同时,测定其促生作用和室内防效。【结果】菌株T1-3-2与桉生假单胞菌(Pseudomonas eucalypticola)亲缘性较近,属于假单胞菌属。该菌株对分属于6个属的10株靶标菌株具有较强的拮抗作用,尤其对炭疽菌属、拟盘多毛孢属、黑孢霉属和葡萄座腔菌属的6株靶标菌株抑制率高达80%以上。室内盆栽试验显示：菌株T1-3-2用Kings Medium B液体培养基的发酵菌液对杉木炭疽病的防效可达74.20%,同时能有效改善杉木幼苗的生长状况、增加生物量。【结论】菌株T1-3-2隶属于假单胞菌属,对杉木具有良好的抗病促生作用,是一株具有开发潜力的生防菌株。     

荧光假单胞菌防治果蔬病害的研究进展

病原微生物侵染引起的果蔬病害日趋严重,现阶段果蔬病害的防治措施主要依赖化学防治,但长期大量施用合成农药的弊端如化学残留、环境污染、抗药性病原菌株出现等日益凸显。近年来,生物防治由于其安全性及高效、经济、环保等优点,成为研究热点。荧光假单胞菌(Pseudomonas fluorescens)分布广泛,施用方便,许多菌株能有效抑制多种病原微生物,成为最具应用价值的一类生防菌和根际促生菌。本文综述了荧光假单胞菌控制果蔬病害的生防效果、主要作用机制(直接寄生作用、营养物质和空间位点竞争、次生抗性代谢物、诱导宿主系统抗性)以及菌剂混配、物理方法、化学处理、分子技术在提高荧光假单胞菌生防效力等方面的研究进展,为荧光假单胞菌在生物防治领域的进一步开发利用提供一定的基础资料。     

荧光假单胞菌感染大鲵的病理损伤

通过对感染荧光假单胞菌(Pseudomonas fluorescents)发病的大鲵(Andrias davidianus)主要器官进行病理剖解和病理组织学观察,以明确大鲵感染荧光假单胞菌引起的病理学损伤特点。结果表明,大鲵感染荧光假单胞菌后,主要表现为腹部极度膨胀、腹水和严重胃肠道反应,严重者可见将胃呕吐至口腔;组织器官具有典型的病理变化,其主要靶器官为肾、肝、肠道、皮肤和肌肉。分别引起坏死性肾小球肾炎、肝炎。此外,还可引起轻微肠炎及皮炎。可在肾小管管腔内、肝细胞坏死灶内、肠道固有层内及皮肤肌肉中发现数量极多的杆状细菌。     

二元融合子与荧光假单胞菌耐药性遗传标记的筛选

应用定性和定量药物敏感性试验与诱变相结合,筛选出荧光假单胞菌56-12-10菌株的遗传标记为链霉素抗性,二元融合子AM-1菌株的遗传标记为环丙沙星抗性,确定了在这两种细菌原生质体融合试验中,选择培养基中链霉素的应用浓度为300Iu/ml,环丙沙星应用浓度为100Iu/ml。     

荧光假单胞菌生防机理的研究进展

荧光假单胞菌是植物根际促生细菌(Plant Growth Promoting Rhizobacteria,PGPR)具有分布广、数量多、营养需要简单、繁殖快、竞争定殖力强的特点。它们能通过产生多种次生代谢物及有效的根际定殖防治植物病害,成为植物生防控制的重要研究对象。主要论述了荧光假单胞菌对植物病害生物防治机理的研究进展。     

荧光假单胞菌鞭毛蛋白对黑松细胞的致死作用

采用细胞免疫荧光分析、细胞染色观察、电导率测定以及基因组DNA电泳分析技术,研究了松材线虫携带的荧光假单胞菌分泌的鞭毛蛋白对黑松愈伤组织细胞的作用及其致死方式。结果表明,鞭毛蛋白与黑松细胞之间存在直接的相互作用;鞭毛蛋白处理的细胞,细胞膜皱缩变形、细胞质浓缩、细胞核解体,形成若干小核,细胞质中的RNA降解;处理细胞的着色力增强,细胞培养液的电导率增加,说明鞭毛蛋白可增加处理细胞的细胞膜透性;基因组DNA的电泳分析证实,处理细胞的DNA发生了断裂,但无明显的梯子形成,推测鞭毛蛋白对黑松细胞的致死方式为非典型的细胞凋亡。     

荧光假单胞菌抗生性代谢产物合成相关基因的研究现状

荧光假单胞菌(Pseudomonas fluorescens)是一种重要的植物根际促生菌,它能够产生藤黄绿脓菌素、2,4-二乙酰基藤黄酚、硝吡咯菌素、吩嗪-1-羧酸等抗生性次级代谢产物,可抑制多种病原物,在农作物土传病害的生物防治研究中具有重要意义.总结了荧光假单胞菌中已确立的抗生性次级代谢产物的合成机制,重点阐述了相关基因的结构、功能,以及利用生物工程技术对荧光假单胞菌进行遗传操作的最新进展,同时对荧光假单胞菌在生物防治中的应用和其作为生防菌剂的前景进行了展望.     

Mechanism of insoluble phosphate solubilization by Pseudomonas fluorescens RAF15 isolated from ginseng rhizosphere and its plant growth-promoting activities

Aims:  To investigate the mechanism of insoluble phosphate (P) solubilization and plant growth-promoting activity by Pseudomonas fluorescens RAF15.
Methods and Results:  We investigated the ability of Ps. fluorescens RAF15 to solubilize insoluble P via two possible mechanisms: proton excretion by ammonium assimilation and organic acid production. There were no clear differences in pH and P solubilization between glucose-ammonium and glucose-nitrate media. P solubilization was significantly promoted with glucose compared to fructose. Regardless of nitrogen sources used, Ps. fluorescens RAF15 solubilized little insoluble P with fructose. High performance liquid chromatography analysis showed that Ps. fluorescens RAF15 produced mainly gluconic and tartaric acids with small amounts of 2-ketogluconic, formic and acetic acids. During the culture, the pH was reduced with increase in gluconic acid concentration and was inversely correlated with soluble P concentration. Ps. fluorescens RAF1 showed the properties related to plant growth promotion: pectinase, protease, lipase, siderophore, hydrogen cyanide, and indoleacetic acid.
Conclusion:  This study indicated that the P solubility was directly correlated with the organic acids produced.
Significance and Impact of the Study:  Pseudomonas fluorescens RAF15 possessed different traits related to plant growth promotion. Therefore, Ps. fluorescens RAF15 could be a potential candidate for the development of biofertilizer or biocontrol agent.     

Ecology of a plant growth-promoting strain of Pseudomonas fluorescens colonizing the maize endorhizosphere in tropical soil

Pseudomonas fluorescens strain BR-5 stimulated the growth of maize in a natural soil and inhibited fungal root pathogens in vitro. Strain BR-5 was detected inside plant cells, indicating that it is able to colonize the endorhizosphere. No significant effect was detected on soil or ectorhizosphere microbial population after inoculation of strain BR-5 onto seeds.     

Pseudomonas fluorescens,a potential bacterial antagonist to control plant diseases

Abstract

Fluorescent Pseudomonads belong to plant Growth Promoting Rhizobacteria (PGPR), the important group of bacteria that play a major role in the plant growth promotion, induced systemic resistance, biological control of pathogens etc. Many strains of Pseudomonas fluorescens are known to enhance plant growth promotion and reduce severity of various diseases. The efficacy of bacterial antagonists in controlling fungal diseases was often better as alone, and sometimes in combination with fungicides. The present review refers to occurrence, distribution, mechanism, growth requirements of P. fluorescens and diseases controlled by the bacterial antagonist in different agricultural and horticultural crops were discussed. The literature in this review helps in future research programmes that aim to promote P. fluorescens as a potential bio-pesticide for augmentative biological control of many diseases of agriculture and horticultural importance.     

Optimization of the hide powder azure assay for quantitating the protease of Pseudomonas fluorescens

The extracellular protease of Pseudomonas fluorescens NC 3 was optimally active at 40°C in a reaction mixture containing: 50 mM HEPES (N-2-hydroxyethylpiperazine-N′-2-ethanesulfonic acid) buffer (pH 6.6), 0.5 mM CaCl₂, and 25 mg hide powder azure in 5 ml total volume. Divalent cation chelators, i.e., EDTA, o-phenanthroline, citrate or phosphate, inhibited the enzyme. Protease production by P. fluorescens NC 3 was initiated during late-logarithmic-growth phase in a sodium caseinate medium and reached its maximum at the onset of the stationary phase.     

Root colonization and iron nutritional status of a Pseudomonas fluorescens in different plant species

Root colonization and induction of an iron stress regulated promoter for siderophore production by Pseudomonas fluorescens 2-79RLI was studied in vitro and in the rhizosphere of different plant species. P. fluorescens 2-79RLI was previously genetically modified with an iron regulated ice nucleation reporter, which allowed calibration of ice nucleation activity with siderophore production. Initial experiments examined ice nucleation activity and siderophore production under different growth conditions in vitro. These studies demonstrated that P. fluorescens 2-79RLI could utilize both Fe-citrate and Fe-phytosiderophore as iron sources, suggesting that production of these compounds by plants would increase iron availability for P. fluorescens 2-79RLI in the rhizosphere. Fe demand and Fe stress were further shown to be a function of nutrient availability and were reduced when carbon was limiting for growth. Subsequent experiments extended these observations to rhizosphere cells. Cells were sampled from the rhizosphere and the rhizoplane. Results of a soil microcosm experiment showed that Fe stress was reduced for P. fluorescens 2-79RLI in the barley rhizosphere as compared to the cells in the rhizosphere.of lupin. In lupin, relative Fe stress of P. fluorescens 2-79RLI was greater at the root tip than in the lateral root zone. In a second experiment comparing zucchini and bean, iron stress was greater for P. fluorescens 2-79RLI associated with zucchini than with bean. In a third experiment with rape plants under P deficient conditions, addition of soluble P was shown to increase Fe stress for P. fluorescens 2-79RLI located at the root tip, but not in the lateral root zone. This study showed that Fe stress of P. fluorescens 2-79RLI in the rhizosphere may be influenced by plant species, P source, root zone and localization of the cells within the rhizosphere.     

Nitrite inhibition of denitrification by Pseudomonas fluorescens

Using a pure culture of Pseudomonas fluorescens as a model system nitrite inhibition of denitrification was studies. A mineral media with acetate and nitrate as sole electron donor and acceptor, respectively, was used. Results obtained in continuous stirred-tank reactors (CSTR) operated at pH values between 6.6 and 7.8 showed that growth inhibition depended only on the nitrite undissociated fraction concentration (nitrous acid). A mathematical model to describe this dependence is put forward. The maximum nitrous acid concentration compatible with cell growth and denitrification activity was found to be 66 mug N/L. Denitrification activity was partially associated with growth, as described by the Luedeking-Piret equation. However, when the freshly inoculated reactor was operated discontinuosly, nitrite accumulation caused growth uncoupling from denitrification activity. The authors suggest that these results can be interpreted considering that (a) nitrous acid acts as a proton uncoupler; and (b) cultures continuoulsy exposed to nitrous acid prevent the uncoupling effect but not the growth inhibition. Examination of the growth dependence on nitrite concentration at pH 7.0 showed that adapted cultures (grown on CSTR) are less sensitive to nitrous acid inhibition than the ones cultivated in batch. (c) 1995 John Wiley & Sons, Inc.