Determination of Fungicidal Activities of Six Antagonistic Actinomycetes in Soil and Their Preliminary Identification

[ Objective] The paper was to preliminarily identify the species of six actinomyeetes strains, and to determine the fungicidal activities of their fermenta- tion products. E Method ] The species of six aefinomyeetes strains were identified by morphological method, and the fungicidal activities of the fermentation products of six aetinomycetes strains were systematically determined by series of methods including mycellal growth rate inhibition method, spore germination method, potting and field test. []Result] Morphological identification results showed that six strains belonged to Streptornyces. Biological determination results indicated that the in- hibition rates of the fermentation products of six actinomycetes strains with the concentration of 500μg/nd against the mycelial growth of Fusar/um oxysporum f. sp. Vasinfeetum were all greater than 90% ; the inhibition rates against the myeelial growth of Botrytis cinerea Pers. , A/ternar/a a/zernate and Fusarium oxysporum were also greater than 80%. The inhibition rates of the fermentation products of GZ-204 and GZ-331 strains against the spore germination of Bipolaria sorokiniana and Cercospora sorghl were 97. 8% , 98.2%, 99.5% and 94.6%, respectively. Potting test showed that the protection effects of the fermentation products of GZ-204 and GZ-331 strains on wheat powdery mildew（Erysiphe graminis） were 78.8% and 87.1% , and their cure effects were 62.4% and 68.5% , respectively. Field test showed that the control effects of 200 times fermentation liquids of GZ-204 and GZ-331 strains on wheat powdery mildew were 50.5% and 69. 2%, respective- ly. [Condusion] The research provided the reference for the development of new pesticides with actinomyeetes as the resource.

Isolation and Preliminary Identification of Antibacterial Active Substances of Antagonistic Actinomycetes against Peach Crown Gall(Agrobacterium tumefaciens)

[ Objective ] The paper was to isolate and preliminarily identify the antibacterial active substances of antagonistic actinomyeete strain G19 obtained from the soil highly affected by peach crown gall （Agrobacterium tumefaciens）. [ Method] The antibacterial substances of antagonistic actinomycete strain G19 were ex- tracted using protein precipitation method, then isolated and purified using high performance liquid chromatography and medium-pressure preparative chromatogra- phy. Its molecular weight was determined by MALDI-TOFMS method, and the related functional groups were verified through chemical color reaction. [ Result] Seven peptide portions were produced from the antibacterial substances of antagonistic actinomycete strain G19 with the molecular weights of 900 - 1 300 Da after isolation and purification. It could be also inferred that it contained Cys, and carried with H2O and Na＋. Color reaction of functional groups verified that the sub- stance was polypeptide containing glycosyl. [ Conclusion] The result provided basis for the final definition of the structure of antibacterial substances in antagonistic actinomycete strain G19.

Isolation,Screening and Identification of Antagonistic Actinomycetes against Ustilago scitaminea Syd

[Objectives] This study was conducted to obtain actinomycetes strains having antagonistic effect on Ustilago scitaminea Syd.[Methods] At first, actinomycetes strains were isolated from 22 soil samples in Hainan sugarcane regions. Then, antagonistic actinomycetes against U. scitaminea were screened by confrontation culture. Finally, the taxonomic status of antagonistic actinomycetes was determined using 16S rDNA.[Results] From the 22 samples, 984 actinomycetes strains were isolated. From all the isolated strains, 23 antagonistic actinomycetes strains were obtained through primary screening, and one strains with better antagonistic effect was then obtained through secondary screening, and designated FAS. 16S rDNA identification showed that strain FAS shared 99% sequence similarity with Streptomyces cealestis US24. A phylogenetic tree was built with MAGE 7.0 software, and the results showed that strain FAS had the shortest genetic distance with S. caelestis US24. Therefore, the actinomycetes FAS was determined as S. caelestis .[Conclusions] This study provides a new biocontrol method for the biological control of sugarcane smut, thereby ensuring sustainable development of sugarcane industry and sugar industry.

Screening of Antagonistic Actinomyces against Soft Rot of Amorphophallus konjac and Its Antibacterial Activity

[Objective] Antagonistic actinomyces of Amorphophallus konjac soft rot were isolated from the soil,the antibacterial activity of the fermentation was detected,and its active components were separated.[Method] The antagonistic actinomycetes were screened using plate confrontation culture method.The SJK18 antagonistic strain with strong activity was conducted single-factor tests using different carbon sources,nitrogen sources,temperatures and pH value as the culture condition,and the antibacterial activities of fermentation liquid was determined,respectively.The fermentation liquid of antagonistic strain was extracted with alcohol and acetic ester,and their antibacterial activities were determined.[Result] A total of 112 strains of actinomycetes were obtained,and 11 strains had antibacterial activity.The antibacterial activity of SJK18 strain was the strongest in the single-factor test,when the corn powder was adopted as the carbon sources,KNO3 was the nitrogen source,the temperature was 30 ℃ and the pH was 6.0,the appropriate pH value for the activity was 5.5-10.0.The diameters of inhibition zone of alcohol extract and raffinate of ethyl acetate were 17.0 and 20.0 mm,respectively,while the extraction of ethyl acetate had no antibacterial activity.[Conclusion] A strain of actinomyces with strong antibacterial activity against soft rot of A.konjac was obtained.

Screening and Identification of Cotton Verticillium Wilt Antagonistic Bacteria Strain 7-30

[Objective]The aim of this study was to screen the antagonistic spore-forming bacteria of Verticillium dahliae and identify its physiological and biochemical characteristics.[Method]Taking the cotton verticillium wilt pathogen Verticillium dahliae V-190 as the test microorganism,the antagonistic spore-forming bacteria were screened.Through the preliminary screening and secondary screening,an antagonistic bacteria strain 7-30 with stronger antibacterial activity was obtained,and its morphological characteristics,physiological and biochemical characteristics were also identified.[Result]84 antagonistic bacteria strains were isolated from soil in various places by the preliminary screening.Especially,18 strains with better antagonistic ability were screened again,so an antagonistic bacteria strain 7-30 with the diameter of inhibition zone 18.9 mm and stronger antibacterial activity was obtained.According to its morphological characteristics,physiological and biochemical characteristics,the antagonistic bacteria strain 7-30 was identified as Bacillus subtilis primarily.[Conclusion]The strain 7-30 was obtained as the antagonistic spore-forming bacteria of Verticillium dahliae.

Screening of Soil Antagonistic Bacteria for Watermelon Fusarium Wilt

[Objective] The aim of this study was to screen bacteria strains with stable antagonistic effect against watermelon fusarium wilt from soil and investigate the biological control of watermelon fusarium wilt by applying the antagonistic bacteria strains into soil.[Method] Actinomycete strains,fluorescent bacteria strains and bacillus strains were isolated from soil samples by the dilution-plate method,then its resistance was screened respectively by the improved confront culture method after colonies were purified.Finally,bacteria strains with better antagonistic effect were identified.[Result] 29 bacteria strains with stable antagonistic effect against watermelon fusarium wilt were screened from 39 soil samples,which contained 15 fluorescent bacteria strains,5 bacillus strains and 9 actinomycete strains.Furthermore,three antagonistic bacteria strains of FM2,FM3 and FM4 with the strongest antagonism were identified primarily.[Conclusion] According to cultural characteristics,morphological observation,biochemical and physiological tests,FM2 belongs to bacillus subtilis,while FM3 and FM4 belong to micrococcus.

α7烟碱型乙酰胆碱受体与阿尔茨海默病的关系

背景:α7烟碱型乙酰胆碱受体在大脑皮质和海马高度表达,并在阿尔茨海默病的病理发展过程中起重要调控作用,是阿尔茨海默病治疗的潜在靶点。目的:总结α7烟碱型乙酰胆碱受体和阿尔茨海默病的密切关系和相互作用机制。方法:检索中国知网、PubMed数据库中相关文献,中文检索词为“α7烟碱型乙酰胆碱受体,阿尔茨海默病,β-淀粉样蛋白,激动剂,正变构调节剂,拮抗剂”;英文检索词为“alpha 7 nicotinic acetylcholine receptor,Alzheimer’s disease,beta amyloid protein,agonist,positive allosteric modulator,antagonist”,文献检索时限为各数据库建库至2024年7月,依据入选标准对检索结果进行录用或排除,最终纳入符合标准的83篇文献进行综述。结果与结论:α7烟碱型乙酰胆碱受体通过与β-淀粉样蛋白的相互作用减轻β-淀粉样蛋白的神经毒性,如促进阿尔茨海默病的突触可塑性和胆碱能突触的快速传递、减轻β-淀粉样蛋白诱导的神经中枢炎症反应、抵抗神经细胞凋亡,从而对阿尔茨海默病患者的脑具有保护作用等。α7烟碱型乙酰胆碱受体作为阿尔茨海默病治疗靶标具有很大的潜能,但是又存在一系列问题有待解决,比如α7烟碱型乙酰胆碱受体的脱敏性、适度活性稳定性及基因多态性等问题。筛选高特异、安全性和以α7烟碱型乙酰胆碱受体为核心的多靶点结合作用的药物,将成为未来阿尔茨海默病治疗研究的一个方向。

Screening of Antagonistic Bacteria against Phytophthora infestans and Its Inhibition Effect

[ Objective ] The paper was to screen bacterial strain with significant antagonistic effect against Phytophthora infestans, so as to provide basis for further development and utilization of antagonistic bacteria to inhibit P. infestans and control potato late bright. [ Method] Plate dual culture and filter paper method were used to determine the inhibition effect of strains in vivo, fermentation broth and bacterial liquid of 61 strains against P. infestans and the resistance-induction effect of SR13-2 strain. [ Result] The inhibition rate of 24 strains among 61 tested strains against mycelial growth of P. infestans was greater than 60%, and the inhibi- tion effect of HT-6 strain was the strongest with the inhibition rate of 89.92%. However, fermentation broth of all tested strains had no significant inhibition effect against P. infestans, while the inhibition effect of bacterial liquid of most strains was significantly higher than strain in vivo; the inhibition effect of $34-1 strain was the strongest with inhibition rate of 91.50%. The bacterial liquid of SR13-2 strain was found to have significant resistance-induction effect with protective rate of 60%. [ Conclusion] The inhibition effect of strains in vivo and fermentation broth of antagonistic strains S34-1 and SR13-2 had no relationship with each other, while bacterial liquid had great application potential in controlling potato late bright.

Phylogenetic Analysis of Actinomycete Isolates from Iron Mine Tailings

[Objective]The aim was to discuss the actinomycete biodiversity of iron-mine tailings by phylogenetic analysis of 12 typical isolates. [Method]The genomic DNAs were extracted by phenol-chloroform method; phylogeny analysis was carried out based on 16S rDNA PCR amplification and sequencing. [Result]The results showed that all the 12 strains belong to the genus Streptomyces sharing 98.7%-99.9% similarities with their nearest known neighbors. [Conclusion]Streptomyces is the dominant culturable actinomycete group of iron mine tailings,in which there are many potential novel species.

Screening and Identification of Antagonistic Strain against Phytophthora sojae

[ Objective] The paper was to screen the antagonistic strain against Phytophthora sojae with biocontrol potential, and provide basis for searching control measures and designing new control strategies against P. sojae. [ Method] The rhizosphere soil of soybean was collected from three different places in Heilongjiang Province, and various soil microorganisms were isolated. Dual culture method was used to screen the microorganism with antagonistic effect against P. sojae. On this basis, the growth inhibition rate of the microorganism with stronger antagonistic effect against P. sojae was determined, and its control effect against P. sojae was also measured. [ Result] A strain of bacterium with relatively good antagonistic effect was isolated from soil, and named as strain B048. Dual test showed that the growth inhibition rate of antagonistic bacterium 11048 against P. sojac reached 97.5%. Antagonistic endurance tests showed that the width of inhibition zone was still 20.0 mm after dual culture with P. sojac for21 d. In potting experiment, the control effect of B048 against P. sojae was 100%. The antagonistic bacterium was primarily identified to be Bacillus pumilus through morphology and 16S rDNA sequence analysis. [Condusion] The antagonistic bacterium B048 had good prospect to be developed as the biocontrol bacterium against P. sojae.

Determination of Growth-promoting and Antagonistic Action of Endophytic Bacteria Strains Itb57 and Itb295 of Tobacco

[ Objective ] The paper was to study the growth-promoting and antagonistic action of endophytic bacteria strains Itb57 and Itb295 of tobacco to explore their functions in biological control. [ Method] The growth-promoting effects of bacterial suspension ~ff endophytic bacteria Itb57 and Itb295 on tobacco seedling un- der different treatment modes were studied using potting method in greenhouse. The antagonistic action of bacterial suspension of endophytic bacteria Itb57 and Itb295 on Phytophthora nicotianae, Alternaria alternata and Botrytis cinerea were measured by duel culture method. [ Result] Bacterial suspensions of enduphytic bacteria Itb57 and Itb295 had certain growth-promoting effects on tobacco seedling, which could significantly increase the fresh weight and dry weight in aerial part; the growth-promoting effect of soaking ＋ spraying and irrigating treatment was the best. Itb57 strain had good antagonistic action against P. nicotianae. A. alterna- ta and B. cinerea, while Itb295 strain only had good antifungal effect against P. nicotianae. [ Conclusion] The results provided basis for the study and application of tobacco endophytic bacteria strains Itb57 and Itb295 in biocontrol of tobacco diseases.

Screening and Identification of Antagonistic Bacteria against Soil-borne Diseases of Tomato

[Objective] This study was conducted to screen resources for biological control of soil-borne diseases of tomato. [Method] Antagonistic bacteria against Ral- stonia solanacearum and Fusarium oxysporum were isolated and purified from soil samples by dilution plating and confronting incubation on PDA plates, then the antibacterial spectrum and metabolic secretions of the bacterial isolates were measured, and their species were identified by establishing phylogenetic trees with Neighbor-Joining method. [Result] From the 60 soil samples, 10 of 59 antagonistic bacteria isolates against R. solanacearum showed inhibition zone diameter 〉 25 mm, and 4 of 30 strains against F. oxysporum exhibited inhibition rate 〉 30%. The bacteriostatic substances and antibacterial spectrum analysis on above 14 isolates revealed that four strains N23-2, N58-2, NF59-3 and NF61-1 had good antago- nism against pathogenic bacteria and fungi; 12 strains produced cellulose, 11 strains produced proteases, and 6 strains produced siderophores. The molecular identification experiments indicated that four strains were members of Paenibacillus, three strains of Streptomyces, three strains of Pseudomonas strains, and four strains of Bacillus strains.

Screening and identification of an antagonistic bacterium strain LHB02 and the optimization of its fermentation conditions

A strain LHB02 with strong antibacterial activity against some aquatic pathogens was screened from the coastal marine sediment in Fujian province, China. LHB02 was identified as Bacillus subtilis, based on its 16S rRNA sequence, together with the morphological, physiological and biochemical characteristics. The antagonistic activity of strain LHB02 and its optimal fermentation conditions were also investigated. The results showed that LHB02 had strong antagonistic activity against 3 species of vibrios： Vibrio harveyi,Vibrio alginolyticus and Vibrio anguillarum, and the optimum fermentation conditions for the strain LHB02 were as follows： KB culture medium （peptone 20 g, glycerol 10 mL, K2HPO4 1.5 g, MgSO 4 .7H2O 1.5 g, H2O 1 000 mL）; temperature, 28 ℃; pH ,7.0; culture time, 36 h; and inoculation amount, 1.5% （v/v）.

Antagonistical Mode of Pichia membranefaciens to Rhizopus stolonifer in Wounds of Peach Fruit

膜醭毕赤酵母 (PichiamembranefaciensHansen)是本实验室从果实上分离获得的一种能有效防治桃果实采后软腐病的拮抗菌。本文将P .membranefaciens与葡枝根霉 (Rhizopusstolonifer)在桃果实伤口部位共培养 2 4h后 ,用扫描电子显微镜观测了它们的拮抗作用。结果表明 ,在有病原菌的地方聚集了大量的酵母拮抗菌 ,而且拮抗菌紧密地吸附在病原菌的菌丝体上。结合以前的研究结果可以推断 ,P .membranefaciens主要通过与病原菌进行营养和空间的竞争 ,紧密地吸附在病原菌菌丝体上分泌能降解病原菌细胞壁的水解酶 (如几丁质酶和 β_1,3_葡聚糖酶 ) ,并可能诱导寄主产生抗性 ,从而抑制桃软腐病的发生。

Isolation of an Actinomycete Strain from Medicinal Plant Rhizosphere Soils with Inhibitory Activity against Yam Anthracnose(Colletotrichum gloeosporioides) and Its Preliminary Identification

[ Objective ] The paper was to isolate actinomycete strains with antagonistic activity against yam anthracnose from the rhizosphere soil of medicinal plants in Hainan Province, and identify its taxonomic status. [ Method ] Using HV medium, actinomycete strains were isolated from the rhizesphere soil of frangipani （Plumeria rubra L. ）. The active antagonistic actinomycetes were selected by using confrontation culture method and antifimgal test of fermentation products. Ac- cording to morphology, combined with 16S rRNA gene analysis, the taxonomic status of active actinomycetes was identified. [ Result] Twelve strains of actinomyce- tes were isolated from the rhizosphere soil of medicinal plant frangipani. Strain 51173 showed significant antifungal activity against Colletotrichum gloeosporioides, which was identified to be a member of Streptomyces violaceusniger 16S rRNA gene clade. [ Conclusion] Strain 51173 showed a good application potential for bio- logical control against yam anthracnose.

Inhibition Effect of Antagonistic Fungal Strain BOS-013 against the Pathogen of Rice Blast (Pyricularia oryzae)

[ ObjeeUve ] To search for the beneficial microorganisms and their metabolic products with control effect against rice Mast, the paper studied the inhibi- tion effect of the fermentation broth of actinomycetes BOS-013 strain against the pathogen of rice blast （Pyricularia oryzae）. [ Method ] With P. oryzae as the target indicator fungus, the inhibition effect of the fermentation broth of BOS-013 strain and its extracts from different solvents against the pathogen were determined using cylinder plate method and filter paper method. [ Result] The results showed that the inhibition rate of the fermentation broth of BOS-013 strain with fungus amount of 4×10^8 cfu/ml against P. oryzae was 92.0% ±0.5% ; the fermentation broth still had inhibition effect against P. oryaae after inactivation under high temperature and high pressure, and the inhibition rate was 60.0%±0.5%. After absorbed by non-polar CAD-45 type macroperous adsorption resin and eluted by 60% etha- nol, the antifungal activity of the fermentation broth was still high, and the diameter of inhibition zone reached 33.0 mm. [ Conclusion] The fermentation broth of BOS-O13 strain had significant inhibition effect against P. oryzae. The results would provide foundation for further clarification of inhibition mechanism of BOS-013 strain fermentation broth against P. oryzae and its practical application.

Genetic Diversity of Antagonistic Endophytic Bacteria Isolated from Sophora alopecuroide

[ Objective ] The paper was to study and analyze the genetic diversity of 48 endophytic bacteria isolated from Sophora alopecuroide with strong antagonis- tic effect against Fusarium oxysporum and Verticillium dahliae, and carry out sequence measurement and phylogenetic analysis on 10 representative strains. [ Meth- od] Using total DNA ERIC-PCR and 16S rRNA sequencing analysis method, a total of 48 endophytic bacteria were carried out genetic diversity and phylogenetic analysis. [Result] ERIC-PCR fingerprint map showed that 48 endophytic bacteria were divided into 6 ERIC groups and 2 strains with independent groups at Wat- son distance of 0.31. Representative strains were selected from each group to determine 16S rRNA gene for phylogenetic analysis, and the results showed that these strains belonged to Bacillus atrophaeus, Bacillus subtilis, Bacillus cereus, Bacillus megaterium, Bacillus pumilus and Serratia marcescens, respectively. [ Conclu- sion ] The genetic diversity of 48 strains of bacteria was obvious. Determination of 48 strains of bacteria on diversity and phylogenetic status could lay foundation for study on mechanism of F. oxysporum and V. dahliae, which could also provide new strain sources for biological control of diseases in cotton production.

Antagonistic Effect of Russula virescens(Schaeff.) Fr.against Bortrytis cinerea

[Objective] The paper was to study the antagonistic effect of Russula virescens （Schaeff.） Ft. against Bortrytis cinerea. [Method] Using the confrontation culture method, the antagonistic effect of mycelium, fermentation broth and mycelial extract of R. virescens against B. cinerea was studied. [Result] The antagonistic ef- fect of R. vivesscens against B. cinerea was mainly manifested as hyperparasitism of mycelium and inhibition effect of metabolites. The inhibition rate of confrontation growth was between 46.9% and 52.3%, and hyperparasitism phenomenon was obvi- ous. The fermentation broth of R. virescens cultured by PDB medium had the strongest growth inhibition effect, and the growth inhibition rate against B. cinerea was the highest of 61.59%. The thermal stability of fermentation broth was good, the mycelial extract of R. virescens had no inhibition effect against the growth of B. cinerea. [Conclusion] The study provided theoretical basis for subsequent differentiation and drug sensitivity of B. cinerea.

不同拉伸方式对健康人膝关节肌肉力量及垂直纵跳表现的即刻影响

背景:静态拉伸可有效改善关节运动幅度,而动态拉伸通过肌肉的激活后增强效应,有效提高肌肉力量及运动表现。目的:探讨不同类型的拉伸方式对膝关节肌肉力量及垂直纵跳表现产生的即刻影响,为寻求最佳拉伸方案、提高运动表现、预防训练损伤提供理论支撑。方法:随机招募30名健康大学生,采用Biodex等速肌力测试仪、Qualisys红外动作捕捉系统及AMTI三维测力台分别采集股四头肌/腘绳肌静态拉伸、股四头肌/腘绳肌动态拉伸、股四头肌动态/腘绳肌静态拉伸、股四头肌静态/腘绳肌动态拉伸后的膝关节肌肉力量及垂直纵跳数据,利用膝关节峰值力矩、平均功率、纵跳高度、垂直地面反作用力峰值及关节运动幅度评估膝关节肌肉力量及垂直纵跳表现。结果与结论:(1)与股四头肌/腘绳肌静态拉伸相比,股四头肌/腘绳肌动态拉伸可显著提高膝关节峰值力矩、平均功率及纵跳高度(P<0.05),股四头肌动态/腘绳肌静态拉伸和股四头肌静态/腘绳肌动态拉伸分别提高伸膝和屈膝峰值力矩和平均功率(P<0.05);(2)与股四头肌/腘绳肌静态拉伸相比,股四头肌静态/腘绳肌动态拉伸后的第二垂直地面反作用力峰值显著下降(P<0.05);股四头肌/腘绳肌动态拉伸后的下肢关节运动幅度显著增加(P<0.05);(3)提示即刻的原动肌/拮抗肌动态拉伸和原动肌动态/拮抗肌静态拉伸可显著提高膝关节肌肉力量、垂直纵跳表现及关节运动幅度;较大的运动幅度有利于提高运动表现,并在着地时更好地吸收地面冲击力;同时,原动肌动态/拮抗肌静态拉伸对膝关节肌肉力量的提升效果优于原动肌/拮抗肌动态拉伸,原动肌静态拉伸/拮抗肌动态拉伸有利于提高垂直纵跳落地时的能量吸收能力,降低落地时损伤的风险。

Screening and Identification of Antagonistic Bacterium ZG-10 against Spot Blotch Disease in Pakchoi

[ Objective] The purpose was to screen bacterium with antagonistic effect against pathogen of spot blotch disease in pakchoi in vegetable field. [Method] More than 200 strains of bacteria which could produce spore were isolated from soil in different places. Through screening and rescreening, the bacteria with higher antibacterial activity were conducted observation about thallus shapes and colony characters, a series of physiological and biochemical tests were performed. [Result] Rescreening results indicated that the strains including ZG-10, ZG-19, ZG-59, ZG-72 and ZG-31 had significant antibacterial activity, which had very high research value and good application prospect for biocontrol on spot blotch disease in pakchoi; the strain ZG-10 was identified to be Bacillus subtilis. [ Conclusion] The strain ZG-10 had biocontrol potential and good development prospect. This research laid certain basis for subsequent research and strated a new way for the application of antagonistic strain and proteinum polypeptide in agdculture.