[Objective]Rice bacterial leaf streak(BLS)is a quarantine-regulated bacterial disease in China caused by Xanthomonas oryzae pv.oryzicola(Xoc),which has severely threatened rice yield and grain quality,becoming one of the main diseases in rice production areas.This study aims to utilize high-quality actinomycete strains to lay a theoretical foundation for developing the products of microbial origin to mitigate crop diseases.[Method]Actinomycete strains were isolated and purified from rhizosphere soil samples of various plants using the serial dilution plating technique.The inhibition ability of different strains against Xoc was compared by measuring the diameter of the inhibition zone.The target strain with the best inhibition effect was selected for preservation and identified through polyphasic characterization integrating morphological traits,physiological-biochemical experiments,and multi-gene alignment analysis.The effects of antagonistic actinomycete on the physiological characteristics of Xoc were investigated by scanning electron microscopy,Fourier-transform infrared spectroscopy(FTIR),intracellular β-galactosidase leakage determination and SDS-PAGE gel electrophoresis.The greenhouse pot control effect test was carried out to study the actual benefit of controlling BLS.The growth-promoting characteristics of antagonistic actinomycete were analyzed by designated medium,and its effects on the growth and development of rice seedlings were investigated by watering growth-promoting experiments.[Result]A total of 80 actinomycete strains were isolated.Among them,strain Sv-6 exhibited the most potent antagonism against Xoc,with inhibition zone diameter of(44.87±0.26)mm.Based on the morphological characteristics and phylogenetic analysis,strain Sv-6 was identified as Streptomyces virginiae.After treatment with the culture filtrate of Sv-6 strain,Xoc cells swelled,shrunk and aggregated.At the same time,the material composition of the membrane surface changed,the permeability increased,and the protein expression decreased.The results of greenhouse pot experiments showed that the lesion inhibition rates of susceptible rice varieties Yongyou 15 and Xiangliangyou 900 were 57.98％-88.25％after being treated with strain Sv-6 culture fluid,which exhibited a good preventive effect on rice infected with Xoc.The growth-promoting characterization confirmed that strain Sv-6 exhibited siderophore production,inorganic phosphate solubilization,and IAA production.The growth-promoting irrigation experiments confirmed that strain Sv-6 enhanced the growth of rice seedlings,and the root length increased by 48.50％after treatment.[Conclusion]S.virginiae Sv-6 exhibits a good control effect on BLS,and has the potential to be developed into green biocontrol agent and microbial fertilizer.

Persicaria lapathifolia var. salicifolia (Sibth.) Miyabe, has long been extensively utilized in traditional medicine for its significant medical values (Seimandi et al, 2021). Despite its extensive use, the leaf blight disease of this plant has never been documented in China. However, in September 2023, the symptoms of leaf blight disease were observed on P. lapathifolia var. salicifolia on the campus of Zhejiang Normal University (29°8'3″ N, 119°37'47″ E), Zhejiang province, China. The disease incidence was 40% on the 50 plants surveyed, according to the field survey. The progression of leaf pathogenesis is mainly divided into three stages. Early symptoms manifested as the light yellow spots on the edges or tips of the leaves, which subsequently developed into brown or yellow irregular lesions and eventually led to the curling and wilting leaves. Thus, the leaf tissues (5 × 5 mm) from the border of diseased and healthy areas were surface-sterilized in 1% sodium hypochlorite for 3 min, followed by 75% ethanol for 30 s, and rinsed three times with sterile water. After drying on sterile filter paper, the leaf tissues were put on PDA medium and cultured at 25°C for 3 days. Seven purified fungal isolates were obtained, and one representative strain was selected for further identification. After that, the isolate was identified by the combination of morphological studies and molecular analysis. The fungi exhibited rapid growth on PDA, attaining a diameter of 80 to 85 mm in 5 days. The colonies were black with a yellow margin, and the reverse sides were light yellow and partly colorless. Moreover, the conidia were brown to black, smooth to slightly rough, measuring 3.2 to 3.8 μm (n = 30) in diameter, with radiated conidial heads and expanded ampulliform phialides under the optical microscope. Therefore, the isolate's characteristics were consistent with the descriptions of Aspergillus welwitschiae (Bres.) Henn. (Gherbawy et al, 2021). To further identify the isolate, the internal transcribed spacer (ITS) region (Gardeset al, 1993) and the second largest RNA polymerase subunit (RPB2) (Liu et al, 1999) were employed for phylogenetic analysis. The obtained sequences were despot in GenBank (Acc. Nos. OR797058 for ITS, OR797058 for RPB2, respectively), and exhibited a high degree of sequence homology to A. welwitschiae (MK450815, MK450818, LC179911, and LC000572), with 99% to 100% identity. Besides, multilocus phylogenetic analysis showed that the isolate gathered into one clade with A. welwitschiae. Based on the integrated morphological and molecular results, the isolate was determined to be A. welwitschiae. Six healthy 1-year-old P. lapathifolia var. salicifolia were used to verify Koch's postulates. Three leaves were wounded with sterile pins and inoculated with the conidial suspension (107 conidia/mL) of isolates, while plants inoculated with sterile water were used as controls. After sealing with plastic wrap for 24 hours, the plants were cultivated at 25 °C and 85% relative humidity. Necrotic lesions were observed on leaves 10 days after inoculation, while the control leaves remained asymptomatic. The fungi were re-isolated from the diseased leaves and identified as the original ones through morphological and molecular identification, confirming Koch's postulates. While A. welwitschiae has been reported to cause the rot disease of Sisal Bole in Brazil (Duarte et al, 2018) and maize ear in Serbia (Nikolic et al., 2023), to our knowledge, this study marks the first report of A. welwitschiae causing leaf blight on P. lapathifolia var. salicifolia in China, extending the host range to A. welwitschiae.

Grifola frondosa has been regarded as healthy food resources for its potentially nutraceutical and pharmaceutical values for centuries. During 2023, a bacterial blotch disease with a 40 % incidence rate was observed in G. frondosa in Qingyuan County, Zhejiang Province, China. The strain isolated from symptomatic tissues was identified as Burkholderia gladioli through a combination of morphological characteristics, biochemical features, and phylogenetic analysis. This is the first documented case of B. gladioli causing bacterial blotch in G. frondosa in China. This research will deepen the understanding and provide a reference for available management of this disease in field.

【Objective】The objective of this study is to isolate and screen the dominant actinomycetes from plant roots and rhizosphere soils in waxberry orchards, explore the seasonal characteristics of the number and distribution of actinomycete populations, and to analyze its application potential in biological control and plant growth promotion.【Method】Samples of plant roots and rhizosphere soils were collected in different seasons from waxberry orchards, and the dominant actinomycetes were isolated and purified by the dilution plate method. Selective media were used to analyze the plant growth-promoting rhizobacteria (PGPR) characteristics of dominant actinomycetes such as nitrogen fixation, phosphorus solubilization, and potassium solubilization. The CAS plate assay was used to detect siderophore production capacity. The Salkowski assay was used to detect IAA production capacity. The colorimetric method was used to detect ACC deaminase activity. The strains with excellent growth-promoting characteristics were identified by test tubes for pro-biogenesis, and their antibacterial activity was analyzed by the flat-confrontation method and the Oxford cup method. Finally, the taxonomic status of the strain with good characteristics was identified by morphological observation, physiological and biochemical tests, and 16S rDNA sequence analysis.【Result】A total of 127 strains of dominant actinomycetes were isolated from two waxberry orchards at different altitudes, including 32 from plant roots and 95 from rhizosphere soils. Compared with those isolated in spring and summer, the actinomycetes isolated in autumn and winter had greater quantity and variety, stronger inhibition and promotion ability. The number of dominant actinomycetes isolated at higher altitudes was significantly higher than at lower altitudes in spring and summer, while in autumn and winter the number of actinomycetes isolated at lower altitudes exceeded that of higher altitudes and far exceeded the total number of actinomycetes isolated in spring and summer in that area. Finally, 46 strains of different species of actinomycetes were obtained, and through the analysis of PGPR characteristics, 35 strains of actinomycetes had obvious growth-promoting characteristics. Among them, strain Sz-11 had 6 growth-promoting characteristics, including nitrogen fixation, inorganic phosphorus solubilization, organic phosphorus solubilization, siderophore production, IAA production and ACC deaminase production, and the test tube identification results showed that it could effectively promote the growth and development of rice seedlings. The seedlings inoculated with strain Sz-11 increased by 36.08% and 22.70% in plant height and root length, respectively. Meanwhile, strain Sz-11 showed good antagonistic activity against various plant pathogenic bacteria, with significant and stable antagonistic effects against Xanthomonas oryzae pv. oryzae (Xoo) and Xanthomonas oryzae pv. oryzicola (Xooc). It was tentatively identified as Streptomyces zaomyceticus by observations, and experiments combined with sequencing analysis.【Conclusion】The number and distribution of dominant actinomycetes in waxberry orchard soil are influenced by season and altitude, and the proportion of growth-promoting strains among culturable actinomycetes is high. S. zaomyceticus has good disease prevention and growth-promoting function, which is expected to be developed into biofertilizer and biocontrol agent for rice production.

McrA为最近在构巢曲霉(Aspergillus nidulans)中发现的全局调控因子,具有调控丝状真菌生长发育和次级代谢的作用,利用生物信息学分析方法找到并克隆紫色红曲霉(Monascus purpureus)中mcrA基因,将其命名为MpMcrA.分析MpMcrA蛋白质理化性质、亲疏水性、亚细胞定位、信号肽、跨膜区域及磷酸化位点、转录因子结合位点以及蛋白质二级结构.利用ProtParam、ProtScale、PSORTII、SignalP4.1等生物信息学软件对MpMcrA进行系统分析.结果表明,MpMcrA基因长1 356 bp,其中含有3个外显子,2个内含子,编码410个氨基酸,与构巢曲霉序列比对蛋白相似性高达64％.预测结果显示,MpMcrA属于亲水蛋白,位于细胞核可能性大,不存在跨膜区域,不属于膜蛋白;不存在剪切位点,不属于分泌蛋白;基因含有54个潜在的磷酸化位点;可能存在5个转录因子结合位点;蛋白结构大部分为无规则卷曲,整体结构较松散.对MpMcrA基因进行了生物信息学分析,得到了基因特征和分析结果.初步确定MpMcrA基因为构巢曲霉同源mcrA 基因,在红曲霉中未见有报道.

为了寻找番茄早疫病的微生物生防制剂,减少该病害对番茄产量与品质的影响.利用共培养法和菌丝生长抑制法从土壤中筛选番茄早疫病害的拮抗菌,并考察其抗菌谱、发酵液稳定性与防效效果.结果表明:成功筛选得到 1 株拮抗番茄早疫病较强的菌株Sa-6,菌丝生长抑制法显示该菌株发酵液对番茄早疫菌丝抑制率达 60.27%;根据形态学、生理生化特征和16S rDNA序列分析结果,鉴定菌株Sa-6为微黄白链霉菌(Streptomy-ces albiflaviniger);其发酵滤液对杨树枯萎病菌、西瓜炭疽病菌等5 种病原真菌及大豆细菌性斑点、水稻细菌性条斑等 8 种病原细菌均具有较好的抑制作用;同时菌株Sa-6发酵滤液对番茄早疫病的防效可达 90%以上.因此,菌株微黄白链霉菌Sa-6有望为微生物生防制剂开发提供优良的菌种资源.

【Objective】The aim is to evaluate the growth promoting ability of Streptomyces zaomyceticus Sz-11 and its biocontrol potential against rice bacterial leaf streak disease, and to explore its preliminary bacteriostatic mechanism.【Methods】The antibacterial spectra of Sz-11 against seven plant pathogenic bacteria and 11 plant pathogenic fungi were determined by Oxford cup method. The growth promoting potential of Sz-11 was evaluated in a seed soaking experiment and irrigation experiment. SDS-polyacrylamide gel electrophoresis（SDS-PAGE）, agarose gel electrophoresis（AGE）, confocal laser scanning microscope（CLSM）, scanning electron microscope（SEM） and fourier transform infrared spectroscopy（FTIR） were used to analyze the effects of the active products in fermentation liquor on Xooc protein expression, genomic DNA synthesis, cell membrane permeability, cell morphology, cell membrane surface material structure and composition. The biocontrol potential of Sz-11 against rice bacterial leaf streak（BLS） disease was studied in a potted experiment.【Results】Sz-11 showed good antagonistic activity against Pseudomonas syringae pv. tomato,Fusarium oxysporum f. sp. momordicae, Colletotrichum orbiculare, Alternaria alternata and other plant pathogens, and had outstanding antagonistic activity against Xanthomonas oryzae（Xoo and Xooc）. Sz-11 can promote the germination and growth of rice seeds, shorten the germination cycle, which can also accelerate the accumulation of organic matter and root differentiation in the vegetative growth stage of rice. Sz-11 can affect Xooc protein expression, change cell membrane permeability and membrane surface material composition, resulting in cell swelling, deformation and death,but does not affect Xooc genome DNA synthesis. The relative control effect of Sz-11 on BLS of four rice varieties ranged from 65.63% to 84.38%, and the prevention effect in advance was better than the post-infection treatment as revealed in a pot experiment. 【Conclusion】Sz-11, with a broad antibacterial spectrum, is a beneficial plant growth promoting rhizobacteria. By functions on the cell membrane and hampering protein synthesis of Xooc, it inhibits the growth and reproduction of pathogenic bacteria, thereby effectively preventing the occurrence of rice bacterial leaf streak disease.Thus, the information listed in this article shows that Sz-11 has utilization potential in biological control.

[目的]紫色红曲霉(Monascuspurpureus)Mp-21次级代谢产物的分离纯化与生物活性研究.[方法]综合运用硅胶柱、反相C18柱和Sephadex LH-20凝胶柱等柱色谱分离技术对紫色红曲霉Mp-21的次级代谢产物进行分离纯化,运用波谱学技术(核磁共振和高分辨质谱技术)鉴定化合物的结构.对鉴定的化合物进行抗氧化与降血糖相关酶抑制活性的测定.[结果]从紫色红曲霉Mp-21次级代谢产物中鉴定出10个活性化合物,分别为FMOC-ALLO-THR(TBU)-OH(1)、quercetin(2)、hesperetin(3)、monascin(4),monasphilone A(5)、oleanolic acid(6)、β-sitosterol(7)、ergosterol(8)、indole-3-carboxylic acid(9)、chlorogenic acid(10).其中化合物 1 为新天然产物,补充了该化合物在自然界中的信息和有机波谱信息,化合物2、6、9、10首次在红曲菌科中发现.在体外清除O2-、DPPH和OH-自由基的抗氧化活性试验中,化合物2(IC50分别为5.07、4.84和27.39μg/mL)表现出较强的抗氧化能力.通过电子顺磁共振技术验证了化合物2对DPPH和OH-自由基具有较强的清除能力.化合物6对α-葡萄糖苷酶具有较强的抑制作用,IC50 为22.87 μg/mL.[结论]紫色红曲霉Mp-21是极具开发性能的优质种质资源,具有开发成抗氧化、降血糖等功能性食品的潜力.

[目的]水稻白叶枯病是水稻的主要细菌性病害之一,严重影响水稻生产.本研究获得一株有效防治水稻白叶枯病的放线菌菌株,探索其对白叶枯病的防效和促进水稻生长的作用,为生防菌的开发利用提供科学依据.[方法]利用梯度稀释涂布法、共培养法和牛津杯法筛选拮抗水稻白叶枯病菌(Xanthomonas oryzae pv.oryzae,Xoo)的放线菌菌株;通过形态特征、生理生化反应、16S rDNA序列和系统发育树分析对其进行分类鉴定;利用共培养法分析目标菌株的抗菌谱;通过96孔板微量稀释法、扫描电子显微镜、微生物粘附碳氢化合物法等探究目标菌株的抑菌作用;通过发酵滤液浸种与菌液喷洒土壤的方法探究其对水稻生长的促进作用;利用盆栽试验探索目标菌株发酵滤液对水稻白叶枯病的防治效果.[结果]从不同生境土壤中分离出140株放线菌菌株,最终筛选得到一株对Xoo具有强拮抗活性的放线菌菌株St-79,其发酵滤液抑菌圈直径为64 mm,并鉴定其为硫藤黄链霉菌(Streptomyces thioluteus).菌株St-79对水稻细菌性条斑病菌(Xanthomonas oryzae pv.oryzicola)、大豆细菌性斑疹病菌(Xanthomonas axonopodis pv.glycines)、油菜黑腐病菌(Xanthomonas campestris pv.campestris)和番茄细菌性叶斑病菌(Pseudomonas syringae pv.tomato)均有拮抗作用.其乙酸乙酯粗提物具有良好的抑制Xoo生长的效果,粗提物对Xoo的最低抑菌浓度为8μg/mL,最低杀灭浓度为32μg/mL;扫描电镜观察结果显示,粗提物对Xoo细胞有很强的损伤作用;粗提物还能改变Xoo细胞内膜通透性,降低Xoo细胞的疏水性.促生试验结果显示,菌株St-79发酵滤液能够促进水稻幼苗的生长.盆栽试验结果显示,菌株St-79发酵滤液对水稻白叶枯病有良好的防治效果,在日本晴、甬优15、甬优1540上的相对防效为65.95％～87.23％,病斑抑制率为69.85％～95.8％,且预防效果优于治疗效果.[结论]获得一株有效防治水稻白叶枯病的放线菌,其对水稻白叶枯病菌有明显的抑制作用,并且可以促进水稻种子的萌发与幼苗的生长.

: Soybean bacterial pustule disease occurs globally, seriously affecting soybean production. To avoid the many short-comings of chemical fungicides, the addition of biocontrol bacteria has gradually become an alternative strategy for the prevention and treatment of soybean bacterial pustule disease. However, there are few reports on the development and prevention of soybean bacterial pustule disease biocontrol agents. In this experiment, a total of 186 strains of actinomycetes were isolated from a variety of plant rhizosphere soil samples using the gradient dilution coating method. Eight strains of actinomycete with antagonistic resistance to Xanthomonas axonopodis pv. glycines ( Xag ) were screened by coculture and Oxford cup methods. Among them, the strain Sl-3 performed the strongest antibacterial activity and the inhibition zone diameter was (32.5±1.5) mm. According to mor-phological characteristics, physiological and biochemical experiments, 16S rDNA sequencing and phylogenetic analysis, the strain Sl-3 was identified as Streptromyces lilacinus . The crude ethyl acetate extract of Streptromyces lilacinus Sl-3 has a good inhibitory effect on the growth of Xag . The lowest inhibitory concentration of the crude extract was determined to be 64 μ g mL –1 by 96-well plate method. Scanning electron microscopy revealed that the crude extract of strain Sl-3 had a certain damage effect on Xag cells, which affected cell division and cell membrane synthesis, thus inhibiting the growth of bacteria. The crude extract also inhibited the production of Xag exopolysaccharide, affected the formation of biofilm, and reduced the toxicity of Xag infection. The results of fourier transform infrared spectroscopy showed that the chemical and physiological on the surface of Xag cells were affected by crude extract treatment, leading to changes in the structure and composition of Xag cell surface substances. The growth promotion test indicated that the fermentation filtrate of the strain Sl-3 can significantly pro-mote the growth of soybean plants. The pot incubation test revealed that the fermentation filtrate of Streptomyces lilacinus Sl-3 had a good control effect on soybean bacterial pustule disease with a relative control effect of 93.17%, and the early prevention effect was better than the treatment after the onset.

为发现绿色安全的水稻白叶枯病天然生物防治微生物,本研究从植物根际土壤中分离获得165株放线菌.利用共培养法和牛津杯法,筛选获得了 5株拮抗水稻白叶枯病菌(Xanthomonas oryzae pv.oryzae,Xoo)的放线菌,其中拮抗能力最强的是S1-10菌株,发酵液抑菌圈直径为62.1 mm±1.5 mm.根据形态特征、生理生化实验、16SrDNA序列和系统发育分析,鉴定S1-10菌株为淡紫灰链霉菌(Streptomyces lavendulae).S1-10菌株发酵液对大豆斑点病菌(Pseudomonas syringae pv.glycinea)、烟草野火病菌(P.syringae pv.tabaci)、油菜黑腐病菌(X.campestris pv.campestris)、大豆斑疹病菌(X.axonopo-dis pv.glycines)、水稻条斑病菌(X.oryzae pv.oryzicola)、烟草青枯病菌(Ralstonia solanacearum)和番茄叶斑病菌(P.syrin-gae pv.tomato)7种植物病原细菌均有拮抗作用.S1-10菌株发酵液具有较好的耐光、耐酸碱和热稳定性.SDS-PAGE电泳结果显示,S1-10菌株可抑制Xoo的蛋白质合成.4个品种水稻(甬优15、湘两优900、嘉丰2号和甬优1540)喷施S1-10菌株发酵液,水稻白叶枯病的病斑抑制率达到82.27％～91.78％.研究结果显示,淡紫灰链霉菌S1-10菌株具有较好的水稻白叶枯病生物防治潜能.

Soybean bacterial pustule disease occurs globally, seriously affecting soybean production. To avoid the many shortcomings of chemical fungicides, the addition of biocontrol bacteria has gradually become an alternative strategy for the prevention and treatment of soybean bacterial pustule disease. However, there are few reports on the development and prevention of soybean bacterial pustule disease biocontrol agents. In this experiment, a total of 186 strains of actinomycetes were isolated from a variety of plant rhizosphere soil samples using the gradient dilution coating method. Eight strains of actinomycete with antagonistic resistance to Xanthomonas axonopodis pv. glycines (Xag) were screened by coculture and Oxford cup methods. Among them, the strain Sl-3 performed the strongest antibacterial activity and the inhibition zone diameter was (32.5±1.5) mm. According to morphological characteristics, physiological and biochemical experiments, 16S rDNA sequencing and phylogenetic analysis, the strain Sl-3 was identified as Streptromyces lilacinus. The crude ethyl acetate extract of Streptromyces lilacinus Sl-3 has a good inhibitory effect on the growth of Xag. The lowest inhibitory concentration of the crude extract was determined to be 64 μg mL -1 by 96-well plate method. Scanning electron microscopy revealed that the crude extract of strain Sl-3 had a certain damage effect on Xag cells, which affected cell division and cell membrane synthesis, thus inhibiting the growth of bacteria. The crude extract also inhibited the production of Xag exopolysaccharide, affected the formation of biofilm, and reduced the toxicity of Xag infection. The results of fourier transform infrared spectroscopy showed that the chemical and physiological indexes of lipids, proteins and nucleic acids on the surface of Xag cells were affected by crude extract treatment, leading to changes in the structure and composition of Xag cell surface substances. The growth promotion test indicated that the fermentation filtrate of the strain Sl-3 can significantly promote the growth of soybean plants. The pot incubation test revealed that the fermentation filtrate of Streptomyces lilacinus Sl-3 had a good control effect on soybean bacterial pustule disease with a relative control effect of 93.17%, and the early prevention effect was better than the treatment after the onset.

[目的]紫色红曲霉(Monascus purpureus)Mp-21胞内次级代谢产物的分离纯化与活性研究.[方法]通过综合运用多种色谱分离方法对次级代谢产物进行分离纯化,最后通过多种图谱数据对化合物进行结构的解析与鉴定.对分离纯化得到的单体化合物进行抗氧化与降血糖相关酶抑制活性的测定.[结果]从紫色红曲霉Mp-21胞内分离纯化并鉴定出3个活性化合物baicalein(1)、genistein(2)、glycitein(3),其中化合物1为首次从红曲菌科中发现,化合物2和3为首次从紫色红曲霉中发现.在体外抗氧化和抑制酶活性试验中,化合物1对1,1-二苯基-2-三硝基苯肼(DPPH)、O2-、OH-自由基具有较强的清除能力,对α-葡萄糖苷酶和α-淀粉酶也具有较强的抑制作用,IC50分别为5.67、17.46、36.40、30.94、430.93 μg/mL.[结论]紫色红曲霉Mp-21具有开发成抗氧化、降血糖等功能性食品的潜力.

红曲霉(Monascus spp.)是一类次级代谢产物极为丰富的食药用丝状真菌,其繁殖能力是大规模工业化生产的前提.以实验室保藏紫色红曲霉(Monascus purpureus)Mp-21为研究对象,通过高通量转录组(RNA-Seq)测序获得菌株转录本数据后进行注释分析,首次克隆出红曲霉繁殖相关wetM基因并进行生物信息学分析.wetM基因开放阅读框内(ORF)长度为1659 bp,负责翻译552个氨基酸,分子式C2605 H4067 N781 O831 S18,分子量60199.76,理论等电点(pI)8.15.进一步对wetM基因中的ORF序列分析得到的WetA蛋白与其他丝状真菌中的WetA蛋白在最后的90个氨基酸显示出极高的相似度,有一定的同源性,其保守结构域含有多个结构类型,属于非典型结构域.

The present manuscript highlights the potential role of Streptomyces roseoverticillatus 63 (Sr-63) against Xanthomonas oryzae pv. oryzae (Xoo), which is the cause of a disastrous bacterial leaf blight disease with rice worldwide. The disease suppression was achieved under greenhouse conditions. A foliar spray of the fermentation broth of Sr-63 significantly reduced the leaf blight symptoms with rice in Xoo inoculated rice plants. Furthermore, we observed that the carbazomycin B, isolated from the fermentation broth of Sr-63, was demonstrated to have antibacterial activity against Xoo with a minimum inhibitory concentration (MIC) of 8 μg mL–1. The results indicated that carbzomycin B hampered the membrane formation of Xoo, reduced the production of xanthomonadin and extracellular polymeric substance (EPS). The fourier transform infrared spectroscopic (FT-IR) indicated that carbazomycin B changed the components of the cell membrane, then caused a change of the cell surface hydrophobicity of Xoo. Scanning electron microscopy revealed that the Xoo cells treated with carbazomycin B exhibited apparent structural deformation. The results also indicated that carbazomycin B had a negative impact on the metabolism of Xoo, carbazomycin B reduced the activity of malate dehydrogenase (MDH) activity and suppressed the protein expression of Xoo. Overall, our data suggests that Streptomyces roseoverticillatus 63 is a promising biocontrol agent that could be used to combat the bacterial leaf blight diseases of rice.

为提高菌核曲霉(Aspergillus sclerotiorum)As-68菌株发酵液对水稻白叶枯病菌的抑菌活性,用响应面法优化培养基配方和发酵条件.通过单因素实验,筛选出适宜的碳源、氮源及其浓度和适宜发酵条件,利用Plackett-Burman设计,探究碳源浓度、氮源浓度、菌龄和转速对抑制水稻白叶枯病菌影响效果,采用最陡爬坡设计和响应面分析法进一步优化,获取最适发酵培养基配方和条件.结果表明:碳源浓度、氮源浓度、菌龄和转速对抑制水稻白叶枯病菌影响效果显著;最适发酵培养基配方和条件为碳源9.46％葡萄糖、氮源0.57％黄豆粉、菌龄6 d、接种量5％、转速170 r·min-1、发酵温度28℃.经模型验证实验优化后抑菌圈直径实际值为(50.10±0.20)mm,较优化前抑菌圈直径增大了52.70％.该实验可为生物农药开发及作物病害防治提供参考,为农业科学的发展奠定基础.

为寻找水稻白叶枯病天然生防药剂,本研究利用共培养和牛津杯法分离筛选植物根际土壤放线菌,共分离纯化获得65株放线菌菌株.在8株能够拮抗水稻白叶枯病菌Xanthomonas oryzae pv.oryzae(Xoo)放线菌菌株中,Sr-63菌株对水稻白叶枯病菌拮抗能力最强,其发酵液抑菌圈直径为46.4 mm±2.3 mm.优化发酵条件后,Sr-63菌株发酵液抑菌圈直径可达50.0 mm±1.2 mm;依据形态特征、生理生化特征和系统发育分析,鉴定菌株Sr-63为玫瑰轮丝链霉菌(Streptomyces ro-seoverticillatus).抗菌谱实验结果表明,Sr-63菌株发酵液对水稻细菌性条斑病菌、大豆细菌性斑疹病菌、番茄细菌性叶斑病菌以及大豆细菌性斑点病菌4种植物病原细菌也有较好的拮抗作用.水稻白叶枯病防效实验结果表明,Sr-63菌株发酵液对水稻白叶枯病具有良好的防治效果,对'Chai Nat 2'、'KDML105'、'Khao luang'3个水稻品种的病斑抑制率均达到了90％以上,且Sr-63菌株的发酵液防治效果优于化学农药叶枯唑.

[目的]分析MpigE的缺失在转录水平对红曲色素产生的影响.[方法]对实验室保存的野生型紫色红曲霉(Monascus purpureus) Mp-21和△MpigE菌株进行高通量转录组测序、注释、表达差异基因功能富集分析和基因通路富集分析,在转录水平揭示MpigE缺失后红曲霉色素产量变化的原因.[结果]通过RNA-Seq测序,每个样品获得7.5-8.5 Gb的原始数据,经过拼接后得到7219个转录本(Unigenes),其中成功注释的为5692个.差异基因表达富集分析发现基因缺失菌株△MpigE相较于野生型菌株Mp-21上调差异基因达到199个,下调差异基因为293个.[结论]MpigE的缺失能够促进红曲霉中中央碳代谢和乙酰辅酶A代谢相关基因的表达以此影响色素生物合成.

综合分析不同来源的红曲制品中红曲霉菌株的多样性,筛选出适用于工业化生产的优质菌株.以红曲米、红腐乳为材料,通过分离、纯化、筛选构建红曲霉菌株资源库;依据形态表观特征、显微特征和ITS基因序列鉴定红曲霉种类;用高效液相色谱等方法分析红曲霉代谢产物产量.结果表明:共获得到40株红曲霉菌株,筛选出11株代表性红曲霉菌株,鉴定出紫色红曲霉(Monascus purpureus)8株,红色红曲霉(M.ruber)、橙色红曲霉(M.aurantiacus)、丛毛红曲霉(M.pilosus)各1株;11株红曲霉菌株的代谢产物存在显著差异,其中FJD菌株红曲色素色价最高,达6863.64 kat·g-1;2A菌株γ-氨基丁酸产量最高,达9.88 mg·g-1;11B菌株莫纳可林K产量最高,达442.50 mg·g-1;11B菌株桔霉素产量最低,为46.03 mg·kg-1.研究有望为红曲霉的工业化生产提供优质菌株,对红曲霉资源的开发与利用具有重要意义.

在模式真菌构巢曲霉中,FlbA蛋白位于分生孢子中心调控途径上游,对分生孢子的形成起激活作用.研究以1株实验室筛选的高产洛伐他汀棒曲霉Ac-32专利菌株的基因组为模板,克隆分生孢子发育相关基因flbA,用双接头PCR法构建flbA基因敲除盒,用根癌农杆菌介导转化法构建棒曲霉转化子库,依据转化子表型特征和分子特征鉴定flbA基因缺失突变株.结果表明:flbA基因全长为2208 bp,翻译对应的氨基酸为734个,理论分子量和等电点分别为78798.75 Da和8.64;棒曲霉与构巢曲霉flbA基因序列同源性为69.9％,氨基酸序列的同源性为76.6％;构建了flbA基因敲除盒和敲除载体,获得了258株棒曲霉转化子,经鉴定得到了1株flbA基因缺失突变株.研究成果为后续探讨棒曲霉flbA基因功能提供了材料,并奠定了理论基础.