蓖麻枯萎病病原菌及其生物学性状研究

蓖麻枯萎病病原菌的分离鉴定表明病原菌为尖孢镰刀菌蓖麻专业型。该菌分生孢子萌发适温２５－２８℃相对湿度为１００％。萌发和生长最适ｐＨ值为６－７天，条件适宜４小时产生芽突，６小时萌发率达７０．２％，致死温度和时间分别为５５℃，２０分钟和６０℃，１０分钟。     

龙牙百合腐败菌的分离鉴定、生物学特性及抑制剂筛选

利用常规组织分离法对湖南隆回地区龙牙百合鳞茎优势腐败菌进行分离纯化,并应用科赫法则验证了分离菌株的致病性,运用形态学和分子生物学技术对腐败菌进行鉴定,同时,探究了9种食品级防腐剂对优势腐败菌的抑制效果。结果表明:引起隆回百合鳞茎腐烂的优势菌是尖孢镰刀菌,该菌菌丝生长和产孢的最适温度分别为30,25℃,菌丝致死温度为66℃处理10min;菌丝在pH 7,8时生长最快,在pH为7时产孢量最大;可利用多种碳氮源,其中,在以葡萄糖和D-果糖为碳源,牛肉膏为氮源的培养基上生长最块;在以D-木糖为碳源、牛肉膏和L-苯丙氨酸为氮源的条件下更利于产孢;光照有利于菌丝生长和产孢。采用9种食品级防腐剂对该优势菌的抑菌试验结果表明,纳他霉素、脱氢乙酸钠和焦亚硫酸钠对该菌具有显著抑菌效果(P0.05),最低抑菌浓度(MIC)分别为150,125,100mg/L。     

芳樟醇对生姜枯萎病菌的抑制作用

为明确芳樟醇对生姜枯萎病菌尖孢镰刀菌(Fusarium oxysporum)的抑菌效果与作用机制,以不同质量浓度的芳樟醇处理尖孢镰刀菌,对尖孢镰刀菌菌丝体生长、孢子萌发和细胞膜的损伤以及防治效果进行系统研究。结果表明：芳樟醇可显著抑制尖孢镰刀菌的菌丝生长,其半数有效浓度为1.183 g/L,最小抑菌浓度(minimal inhibitory concentration,MIC)为2.0 g/L,抑制效果与芳樟醇质量浓度呈剂量效应关系;以芳樟醇MIC处理尖孢镰刀菌6 h,其孢子浓度为(1.43±0.12)×10⁴ spores/mL,显著低于对照组((5.79±0.19)×10⁴ spores/mL)(P<0.05);MIC芳樟醇处理枯萎病菌尖孢镰刀菌12 h,其孢子萌发率仅为(5.83±2.16)%,显著低于对照组((95.12±3.78)%)(P<0.05)。1/2 MIC与MIC芳樟醇处理破坏了细胞膜的完整性,导致菌丝悬液中相对电导率、核酸渗漏量显著增加,菌丝中丙二醛浓度也显著增加,麦角固醇含量显著降低,减弱了尖孢镰刀菌的致病...     

一株梨孢镰刀菌的分离与鉴定及其生长特性研究

从大麦表面分离出一株引起啤酒喷涌的镰刀菌,根据菌株在PDA上的菌落特征、菌丝和孢子形态,以及26srDNA序列,鉴定为Fusarium poae(AY188915.1).该菌的最适生长温度为25℃,最适pH为6,最适转速为200r/min,制麦条件适合该菌生长.     

一株梨孢镰刀菌的分离与鉴定及其生长特性研究

从大麦表面分离出一株引起啤酒喷涌的镰刀菌,根据菌株在PDA上的菌落特征、菌丝和孢子形态,以及26s rDNA序列,鉴定为Fusarium poae(AY188915.1)。该菌的最适生长温度为25℃,最适pH为6,最适转速为200r/min,制麦条件适合该菌生长。      

一株高产果胶酶的真菌分离鉴定及酶学特性

以果胶为唯一碳源,对采集自湖南武冈市脐橙果园土样（pH 5.5～6.5）进行富集筛选,分离得到一株产果胶酶的菌株,编号为BM201。根据形态学观察、ITS rDNA及28S rDNA D1/D2序列同源性比对及系统进化分析对菌株进行多相鉴定,初步将该菌株鉴定为尖孢镰刀菌（Fusarium oxysporum）BM201。该菌株发酵产酶条件为30 ℃、160 r/min摇床发酵培养3 d,在该条件下获得的果胶酶酶活为421 U/L。该酶最适反应温度为50 ℃,在30～50 ℃条件下处理60 min,该酶的相对酶活在80%以上,表明该酶的热稳定性较好;该酶的最适作用pH值为5.0,在pH 4.0～7.0下处理60 min,该酶的相对酶活在50%以上,表明该酶在酸性条件下的稳定性较好。     

一株野生口蘑的鉴定及生物学特性

对1 株采自青海的野生口蘑菌株进行形态学观察和真菌种属（internally transcribed spacer,ITS）鉴定,并研究其菌丝生长阶段的最适母种培养基、碳源、氮源、无机盐、生长因子、pH 值和温度。结果表明,形态学观察及ITS 鉴定该菌株为中国美味蘑菇,属担子菌纲,伞菌目,蘑菇科,蘑菇属。最佳母种培养基配方为马铃薯葡萄糖琼脂（potato dextrose agar,PDA）综合培养基配方,即马铃薯200 g,葡萄糖20 g,磷酸二氢钾2 g,硫酸镁1 g,琼脂20 g,水1 000 mL;最适碳源为葡萄糖和麦芽糖;不添加氮源的条件下更利于其菌丝生长;在PDA 培养基中添加不同无机盐和生长因子对菌丝长速影响不大;最适温度为25 ℃;最适pH 值为7。     

致病性尖孢镰刀拮抗菌的筛选与鉴定

该研究从清香型白酒大曲中筛选出一株对致病性尖孢镰刀菌（Fusarium oxysporum）拮抗效果最好的拮抗菌株,采用形态观 察、生理生化试验和16S rRNA序列分析对其进行鉴定,并绘制该菌株生长曲线、考察其培养液中的蛋白类及脂肽类物质的抑菌效 果。 结果表明,从清香型白酒大曲中筛选出一株对致病性尖孢镰刀菌拮抗效果最好的拮抗菌株,编号为P9,其抑菌圈直径达到20 mm 左右。 经鉴定,拮抗菌P9为贝莱斯芽孢杆菌（Bacillus velezensis）;生长曲线结果表明,拮抗菌P9在第9小时生长速率达到最大;抑菌物 质提取实验表明,拮抗菌P9能分泌具有抑菌作用的蛋白类物质及脂肽类物质。     

烟草灰霉病病原鉴定及其生物学特性

对广西烟草灰霉病的病原、生物学特性进行了初步的研究.根据该病原菌的形态特征、致病性及rDNA-ITS序列测定,将该病原菌鉴定为灰葡萄孢(Botrytis cinerea Pers).该病原菌菌丝在5℃-30℃的温度范围内均可生长,产生分生孢子的温度范围为10℃-25℃,菌核形成温度范围为15℃-22.5℃,最适温度均为20℃;分生孢子萌发的温度范围为7.5℃-30℃,最适温度为20℃-25℃.在pH2-9的范围内该菌均能生长,最适pH为6.分生孢子需在高湿条件下才能萌发,相对湿度低于100％时不能萌发.完全光照对该菌菌丝生长有促进作用,而完全黑暗更利于产孢、孢子萌发及菌核的形成.单糖及双糖、有机氮及硝态氮足病原菌较好的C、N源.分生孢子和菌核的致死温度分别是42℃和46℃.     

贵州省都匀市茶轮斑病病原菌鉴定及生物学特性的研究

对贵州省都匀市出现的茶轮斑病的症状进行了系统的描述,采用致病性试验、形态学观察及分子生物学的方法对茶轮斑病的病原菌进行鉴定。致病性试验证实,不同的接种方法对茶叶的致病力均有不同。对病原菌rDNA-ITS区进行了PCR扩增和序列测定。综合形态特征、致病力和分子序列分析结果,确定茶轮斑病病原菌为茶拟盘多毛孢菌(Pestalotiopsis theae)。     

Increased effectiveness of the Trichoderma harzianum isolate T‐78 against Fusarium wilt on melon plants under nursery conditions

BACKGROUND: The use of isolates of the genus Trichoderma to control Fusarium wilt in melon plants is one of the most recent and effective alternatives to chemical treatments. In this work we have studied the immobilization of the isolate Trichoderma harzianum T‐78 on different carriers as an efficient method to control vascular Fusarium wilt of melon in nurseries. Different formulations were developed: liquids (spore suspension, guar gum and carboxymethylcellulose) and solids (bentonite, vermiculite and wheat bran). RESULTS: The introduction of F. oxysporum resulted in a significant decrease in seedling fresh weight. The treatments which gave a lesser reduction in weight and showing a greater biocontrol effect were the liquid conidial suspension and the solid treatments with bentonite and superficial vermiculite. Microbiological analyses revealed that the conidial suspension and all the solid treatments, except wheat bran, significantly decreased F. oxysporum populations. Of all the treatments assayed, bentonite produced the greatest decline in the F. oxysporum population. CONCLUSIONS: The most effective treatments against Fusarium wilt on melon plants were the solid treatments bentonite and superficial vermiculite. These two treatments gave the greatest plant weight, the lowest percentage of infected plants and the greatest T. harzianum population throughout the assay. Copyright © 2009 Society of Chemical Industry     

花生青枯菌红安分离物的鉴定

从湖北红安发病花生根部分离到一个细菌分离物2C1,对该分离物进行了TZC显色反应,致病力的测定,16S rRNA、23S rRNA和鞭毛蛋白基因filC的PCR扩增,16S rRNA PCR扩增产物的序列分析。结果显示,分离物2C1在TZC培养基上表现出青枯菌的典型菌落形态,对花生具有强致病性,PCR扩增获得与预期大小的产物片段;16S rRNA核苷酸序列具有与其它青枯菌分离物99%左右的一致性。上述结果表明：2C1是具有强致病力的花生青枯菌分离物。     

谷物及其制品中脱氧雪腐镰刀菌烯醇控制的研究进展

脱氧雪腐镰刀菌烯醇(deoxynivalenol,DON)属B型单端孢霉烯族毒素,是目前谷物及其制品中污染最为普遍的一种真菌毒素,食用后会导致人体多种急、慢性中毒,增加人体患胃癌、食管癌等恶性肿瘤的几率,具有明显的毒理学危害.为了保护消费者健康及最大限度的减少经济损失,国内外学者一直在积极的寻找控制DON的方法,反复测...     

Identification and characterization of a chitinase of Stenotrophomonas maltophilia, a bacterium that is antagonistic towards fungal phytopathogens

A rhizosphere strain of Stenotrophomonas maltophilia strain MUJ that is strongly antagonistic towards fungal phytopathogens secretes to the culture medium a single form of active chitinolytic enzyme belonging to family 18 of glycosyl hydrolases. The chitinase was purified by a two-stage procedure embracing fractionation with ammonium sulfate and affinity chromatography. The molecular mass of the purified enzyme determined by SDS-PAGE was approximately 52 kDa. The enzyme demonstrated highest activity at 45°C and pH 6.8. The enzymatic protein showed considerable thermal stability during 2 h incubation at 45°C. The activity of the enzyme was strongly inhibited in the presence of Hg²⁺ and Cu²⁺. By applying mass spectrometry analysis, the peptides derived from the purified chitinase were assigned to amino acid sequences of the type ChiA chitinases synthesized by Stenotrophomonas bacteria. The purified enzyme inhibited the growth of fungal phytopathogens belonging to the genera Fusarium, Rhizoctonia and Alternaria.     

小麦中致病真菌的分离鉴定及熏蒸对其毒力的影响

小麦受镰刀菌的感染会导致赤霉病、真菌毒素污染和减产,镰刀菌对粮食安全有着严重威胁。通过对小麦中镰刀菌株进行分离鉴定,分离出的三种菌株N1、N2、N3分别属于禾谷镰刀菌属、亚洲镰刀菌属和高秆镰刀菌属。利用产毒基因检测和真菌毒素检测对三株菌株玉米赤霉烯酮、呕吐毒素和伏马毒素的产毒情况进行分析,结果一致显示N1和N3能产生玉米赤霉烯酮和呕吐毒素,均含有PSK和Tri5两种产毒基因,而N2不产生这三种毒素。进一步通过臭氧和二氧化氯进行气体熏蒸,探究气体熏蒸对分离出的三株菌株的影响,通过观察孢子形态、菌丝体长度、菌丝形态,结果表明二氧化氯熏蒸能有效抑制菌丝生长和孢子萌发,低浓度二氧化氯（300 mg/L）处理0.5 h,可明显抑制菌丝的生长。而臭氧只能抑制孢子萌发,对菌丝的生长没有明显的抑制作用。     

香蕉枯萎病致病菌尖孢镰刀菌4号生理小种micro-like RNA及其靶标基因的鉴定

香蕉枯萎病已严重威胁香蕉产业的发展,为了分析香蕉枯萎病菌尖孢镰刀菌古巴专化型4号生理小种(Fusarium oxysporum F.sp.cubense race 4,Foc4)中miRNA-like(milRNA)及其调控功能,本研究构建了3个Foc4菌丝小RNA测序文库,测序得到原始数据11783990条,其中可用...     

一株高产乳酸菌株的鉴定及其发酵特性研究

采用MRS培养基从果醋醋醅中分离具有强产酸能力的乳酸菌,通过形态观察、生理生化试验及分子生物学技术对其进行鉴定,并研究其乙醇耐受能力、产酸能力和抗生素敏感性。结果表明,从果醋醋醅中分离得到一株产酸能力较高的菌株,编号为D2,并鉴定其为鼠李糖乳杆菌（Lactobacillus rhamnosus）,该菌株在体积分数4%乙醇条件下能够正常生长,在体积分数14%乙醇条件下能够存活,具有较强的乙醇耐受力;在MRS肉汤培养基中发酵48 h时,总酸含量达到20.03 g/L,其中乳酸含量增加最多,其次是苹果酸和琥珀酸;对四环素、氯霉素、红霉素和吉他霉素敏感,对链霉素、卡那霉素、青霉素、苯唑西林和复方新诺明具有耐药性。综上,该菌株具有较强的乙醇耐受能力和产乳酸能力,安全性高,有作为发酵菌剂改善果醋风味和口感的潜在应用价值。     

Identification and characterization of yeasts causing chalk mould defects on par-baked bread

Pichia anomala, Hyphopichia burtonii and Saccharomycopsis fibuligera are spoilage yeasts causing chalk mould defects on par-baked breads packaged under modified atmosphere. The first objective of this study was to identify yeasts isolated from spoiled par-baked breads by means of a RAPD protocol and to determine the dominant spoilers amongst identified strains. The second objective was to determine the effects of water activity (a_w) and pH value on the growth rates and lag phase durations of P. anomala, H. burtonii and S. fibuligera. 95% of the yeasts tested were identified as P. anomala and 5% as S. fibuligera, H. burtonii was not detected. In order to investigate the effect of a_w and pH the growth of the three yeasts was tested within an a_w range of 0.88-0.98 and a pH range of 2.8-8.0. P. anomala was able to grow from pH 2.8 to 8 without a clear optimum. S. fibuligera and H. burtonii showed a pH optimum for growth of 5. The optimum water activity for growth was different for the three strains and varied between 0.96 and 0.98. These growth data were further used to develop secondary models that describe the relationship between a_w and the radial or colony growth rate (g, mm/d) or the lag phase duration (λ, d). The identification of the spoilage organisms and a good understanding of the effects of a_w and pH on the growth behavior is essential for future development of adequate conservation strategies against chalk mould defects.