Carriage of Bacteria Antagonistic Towards Staphylococcus intermedius on Canine Skin and Mucosal Surfaces

Abstract— Antagonism against Staphylococcus intermedius was investigated amongst bacteria isolated from skin and mucosae of (1) 15 dogs with pyoderma and (2) 42 healthy dogs, including household pets, laboratory beagles and guide dogs. Fifteen isolates of S. intermedius, four coagulase-negative staphylococci and a Micrococcus were inhibitory in vitro against at least one of the three indicator strains using direct and deferred inhibition tests. More dogs with antagonists were found in the pyoderma group and amongst laboratory beagles (p < 0.05) compared to healthy household pets. The frequency of all antagonists and of antagonistic S. intermedius from mucosae was higher in the pyoderma group compared to healthy household pets (p < 0.01 for both) and all healthy animals (p < 0.05 and p < 0.01, respectively). Increased competition at mucosae of infected dogs caused by higher populations of bacteria may have favoured the selection of antagonistic strains. Further studies, including tests for adherence and virulence are required to determine whether these isolates could be used as interfering strains against canine pyoderma. Résumé— L'antagonisme contre Staphylococcus intermedius a étéétudié parmi des bactéries isolées à partir de la peau et des muqueuses de 15 chiens présentant des pyodermites et de 42 chiens sains, effectif comprenant des chiens de particuliers, des beagles de laboratoire et des chiens guides. Parmi les souches isolées, 15 S. intermedius, 4 staphylocoques coagulase négatifs et un micrococcus se sont révélés inhibiteurs in vitro vis à vis d'au moins une des 3 souches indicatrices, à la fois dans des test d'inhibition directs et indirects. La plupart des chiens portcurs d'antagonistes appartenait au groupe pyodermite et au groupe beagles de laboratoire (p < 0,05) plutôt qu'au groupe chiens de particuliers sains. La fréquence de tous les antagonistes et du S. intermedius antagoniste isolés à partir des muqueuses était supérieure dans le groupe pyodermite par rapport au groupe chiens de particuliers sains (p < 0,01) pour les 2) et au groupe incluant la totalité des animaux sains (p <0,05 et p < 0,01 respectivement). Une compétition accrue au niveau des muqueuses de chiens infectés causée par un plus grand nombre de bactéries peut favoriser la sélection de souches antagonistes. D'autres études incluant des tests d'adhérence et de virulence sont nécessaires pour déterminer si ces souches isolées peuvent être utilisées comme antagonistes dans les infections cutanées. [Saijonmaa-Koulumies, L. E., LLOyD, D. H. Carriage of bacteria antagonistic towards Staphylococcus intermedius on canine skin and mucosal surfaces (Portage de bactéries antagonistes de Staphylococcus intermedius sur les surfaces muqueuses et cutanées chez le chien).     

壳聚糖对蔬菜土传病原菌的拮抗作用

试验结果表明,不同分子量壳聚糖对供试病原菌均有一定程度的拮抗作用,对RhizoctoniasolaniKühn的抑制作用最高达60.7%.其次是对Fusarium的抑菌率为56.8 %,对PhytopthoracapsiciLeon的拮抗作用较弱。     

Hyperparasites of Rhizoctonia solani in Dutch potato fields

Gliocladium roseum was found to be the most common and probably the most effective mycoparasite in potato fields in the northern parts of the Netherlands. It is able to parasitize and kill living hyphae at temperatures of 12°C and higher. Sclerotia ofR. solani are often infected and killed by this fungus under suitable conditions, i.e. at temperatures of 16°C and more. Killing of sclerotia by other antagonistic organisms was also observed. It is also shown by not parasitic fungi and is caused by toxins produced by the antagonist.The development of theG. roseum population was studied during the growth of a potato crop in two soils. In both soils its initial level was very low. In both a slightly acid sandy soil and a neutral sandy loam, suppression ofR. solani can occur;G. roseum accumulated in the former mainly under continuous potato crops,Colletotrichum coccodes was the main antagonist in the latter.Samenvatting In de meeste Nederlandse aardappelakkers komen schimmels voor dieRhizoctonia solani kunnen aantasten en doden. De meest algemene, en waarschijnlijk ook de meest belangrijke, die we tot nu toe vonden, isGliocladium roseum (Tabel 1). Het is bekend, dat deze schimmel stoffen produceert die voorR. solani giftig zijn. Met behulp hiervan kanG. roseum, evenals andere antibiotisch actieve micro-organismen, ook de sclerotiën doden (Tabel 2). Voor doding doorG. roseum is de temperatuur een factor van belang. Hyfen worden nog gedood bij een temperatuur van 12°C, waarbij de sclerotiën niet meer aangetast kunnen worden. Gedurende het winterseizoen worden sclerotiën door deze schimmel naar alle waarschijnlijkheid niet gedood.De ontwikkeling van de populatie vanG. roseum en andere antagonisten vanR. solani werd gevolgd in aardappelvelden op een licht zure zandgrond en op een neutrale zware zavel. Op de zandgrond werden twee proefplekken bemonsterd: één waarop voor het vierde achtereenvolgende jaar aardappelen werden geteeld en één met een vruchtwisselingsschema van graan, bieten en aardappelen.In de zandgrond nam in het groeiseizoen de populatie vanG. roseum toe. Op de proefplek waar voor het vierde jaar achtereen aardappelen stonden werdR. solani vanaf half augustus onderdrukt, evenwel niet volledig. Ook in het vruchtwisselingsstuk breiddeG. roseum zich flink uit, doch een onderdrukking vanR. solani werd niet bereikt.In de zware zavel nam de populatie vanG. roseum niet toe. Hier werdR. solani — uit besmet pootgoed — onderdrukt doorColletotrichum coccodes (zelf een pathogeen van stolonen) en antagonistische bacteriën. De resultaten zijn vermeld in Tabel 3.De besmetting van de geoogste knollen met sclerotiën, zoals die voorkwam op de zandgrond, is in Tabel 4 vermeld. Op de zavel leverde schoon pootgoed een bijna schone oogst (2% van de knollen was zeer licht bezet met sclerotiën). Besmet pootgoed leverde een oogst met 58% schone knollen, 35% met een zeer lichte en 7% met een iets zwaardere sclerotiënbezetting. Hoewel uit 100% besmet pootgoed een veel schonere oogst werd verkregen, was eerder toch een beschadiging van het gewas opgetreden. Pas tegen het eind van het groeiseizoen werdR. solani flink onderdrukt.     

拮抗油菜菌核病菌的荧光假单胞杆菌的分离与筛选

2003—2005年,在上海市郊采集常见作物的根际土壤样品,经分离和纯化后共得到254个产荧光的细菌菌株。采用平板对峙培养法测定这些菌株对油菜菌核病菌的拮抗效果,结果从这254个菌株中筛选出了一个高效菌株P13。试验表明,它对菌核病菌的生长具有较强的拮抗能力,同时还发现其对多种常见的植物病原真菌具有广谱拮抗作用。通过显微观察发现,P13菌株可致使油菜菌核病菌菌丝生长形态异常,出现菌丝变形、菌丝壁溃解、原生质浓缩及外渗等异常现象,还可在一定程度上抑制菌核的形成。经电镜观察、培养物特征和一系列的生理生化实验鉴定,可初步确定P13菌株为产荧光假单胞杆菌属中的荧光假单胞杆菌。     

Antagonism of Detomidine-Induced Sedation,Analgesia, Clinicophysiological,and Hematobiochemical Effects in Donkeys Using IV Tolazoline or Atipamezole

The present study aimed to investigate and evaluate the reversal of sedation, analgesia, ataxia, clinicophysiological findings, and hematobiochemical effects of detomidine by subsequent IV administration of tolazoline or atipamezole to improve safety and utility of detomidine in donkeys. Six mature donkeys weighing 250–300 kg and aged 4–6 years were used on three separate occasions. Each donkey received the following three treatments at the rate of one treatment per week in a randomized crossover study. The first group received 0.04 mg/kg bwt detomidine. The second group received 0.04 mg/kg bwt detomidine followed by 4.0 mg/kg bwt tolazoline. The third group received 0.04 mg/kg bwt detomidine followed by 0.4 mg/kg bwt atipamezole. Sedation, analgesia, ataxia, pulse rate, respiratory rate, and rectal temperature were recorded at 5 minutes before, then at 5, 15, 30, 60, and 90 minutes after injections. Red blood cell and white blood cell counts, Packed cell volume (%), hemoglobin, total protein, cholesterol, glucose, urea, aspartate amino transferase, alanine amino transferase, and gamma glutamyl transferase values were determined. Detomidine induced deep sedation, complete analgesia, and significant ataxia. Pulse and respiratory rates were decreased from the base line values, although rectal temperature was within the baseline value. The alterations in hematological and hematobiochemical parameters were mild and transient.     

Disruption of bacterial quorum sensing: an unexplored strategy to fight infections in aquaculture

Disease outbreaks—some of them caused by pathogenic bacteria—are considered to be one of the largest constraints to development of the aquaculture sector. So far, antibiotics and disinfectants have only had limited success in the prevention or cure of aquatic disease. Moreover, the frequent use of biocides, especially in subtherapeutic doses, is leading to the rapid development of resistance. Therefore, there is an urgent need to develop alternative ways to control infections caused by bacterial pathogens in aquaculture. Many of these pathogens are found to control virulence factor expression by a cell-to-cell communication system. Hence, disruption of bacterial quorum sensing has been proposed as a new anti-infective strategy and several techniques that could be used to disrupt quorum sensing have been investigated. These techniques comprise (1) the inhibition of signal molecule biosynthesis, (2) the application of quorum sensing antagonists (including natural occurring as well as synthetic halogenated furanones, antagonistic quorum sensing molecules and undefined exudates of higher plants and algae), (3) the chemical inactivation of quorum sensing signals by oxidised halogen antimicrobials, (4) signal molecule biodegradation by bacterial lactonases and by bacterial and eukaryotic acylases and (5) the application of quorum sensing agonists. The few reports that deal with disruption of quorum sensing of aquatic pathogens, together with the results obtained with human and plant pathogens, indicate that this new approach has potential in fighting infections in aquaculture. However, before this new strategy can be applied in aquaculture, the impact of quorum sensing disruption on the virulence of aquatic pathogens and the impact of the proposed quorum sensing disrupting techniques on the aquaculture system of interest should be studied in more depth.     

YAG激光对番茄早疫病菌拮抗菌WB7的诱变效应

[目的]探明YAG激光对枯草芽孢杆菌WB7诱变作用。[方法]采用YAG激光(波长1060 nm,功率7 W)照射1株对番茄早疫病菌有拮抗作用的枯草芽孢杆菌WB7,综合各辐照时间组里菌株致死率和正变率的大小以及拮抗能力提高程度,分析不同辐照时间对WB7生长以及诱变的影响效果。采用连续传代培养,测定正变株拮抗能力的遗传稳定性。[结果]利用YAG激光辐照枯草芽孢杆菌对WB7有显著的诱变效应,不同辐照时间的诱变率有显著性变化,辐照1.5 min诱变作用最强,且正变率最大;筛选的最佳突变株WB7-L1.5’5高抗番茄早疫病菌,经过7代传代试验证明其可稳定遗传。[结论]该研究建立了YAG激光诱变枯草芽孢杆菌WB7的试验体系,对番茄早疫病的生物防治具有广阔的应用前景。     

硒对铅胁迫下油菜酶活性及叶绿素含量的影响

[目的]为油菜作为重金属污染土壤的修复植物提供参考。[方法]以浓度为500 mg/L的铅溶液胁迫下的油菜苗为材料,用浓度为0(CK)、5、10、15、20、25、30 mg/L的亚硒酸钠溶液进行处理,研究硒对铅胁迫下油菜酶活性及叶绿素含量的影响。[结果]当硒浓度低于15mg/L时,油菜的根冠比提高;当浓度高于15 mg/L时,随着硒浓度的增加,根冠比下降。硒在一定浓度范围内(低于10 mg/L)可提高相对SOD、POD、CAT的活性,相对SOD活性的变化最为明显;硒浓度高于10 mg/L时会降低酶活性。硒浓度低于10 mg/L时可增加叶绿素含量;浓度高于15 mg/L时,加剧叶绿素含量的减少。[结论]当浓度低于10 mg/L时,硒与铅呈现拮抗作用;当浓度高于10 mg/L时,硒与铅呈现协同作用。     

筛选用于防治大豆尖孢镰刀菌根腐病的木霉菌株

采用平板对峙培养、温室盆栽的方法筛选来自黑龙江省海伦大豆轮作区的木霉菌,用于防治大豆尖孢镰刀菌根腐病.共测试了80个木霉菌株,筛选出3个防治效果较好的木霉菌株MM35、MM9、MM3 ,相对防效分别为26.95%～66.34%、21.52%～63.70%、22.78%～51.05%.盆栽试验表明MM35能够降低大豆根腐病的主要病原菌-尖孢镰刀菌(Fusarium oxysporum)在土壤中的种群数目.其中MM9对大豆植株能起到增生作用,MM35、MM3则无明显的促生作用.