一株新的耐辐射菌Deinococcus guangxiensis sp.nov.的分离鉴定及耐辐射特性分析

摘要：【目的】从广西大学辐射中心辐射源附近被常年辐射的水样中分离并鉴定出新的耐辐射菌株,并对其耐辐射特性进行研究。【方法】通过GBM培养基分离培养得到一株新的耐辐射菌株,命名为WGR700T。应用生理生化试验,脂肪酸含量,(G+C) mol％含量测定以及16S rRNA序列同源性分析等方法对菌株进行鉴定,同时对WGR700T的耐辐射特性进行分析。【结果】菌株WGR700T为革兰氏阴性,杆状,没有鞭毛,不能运动,厌氧并能产生红色素。最佳生长温度和PH分别为37℃和pH7.0,主要的呼吸醌是MK-8,细胞壁内还有鸟氨酸,主要脂肪酸为16:1ω7c, 16:0, 15:1ω6c, iso-15:0和 iso-17:0。G+C含量为64.7mol%。菌株WGR700T具有很强的UV(>728 J/m2)和电离辐射抗性(D10 = 9.8 kGy)。菌株WGR700T和奇异球菌属（Deinococcus）内其它菌种16S rRNA有很高的相似性（87.1-95.6%）。【结论】根据16S rRNA及生理生化特征区别,菌株WGR700T应是奇异球菌属的一个新种,命名为Deinococcus guangxiensis sp. nov. 模式菌株为WGR700T(= CGMCC1.7045T =CICC 10360T = JCM 15082T)。     

大豆根瘤内抗棉花枯萎病菌株的筛选及其防病试验

【目的】采用优良抗病性内生菌资源来控制棉花枯萎病是一种有效的措施。本研究从大豆根瘤中筛选棉花枯萎病拮抗性内生细菌,探索其对棉花枯萎病菌丝的抑制作用和代表菌株特性,为发掘和应用防病、抗逆优良菌株提供理论基础。【方法】采用对峙法和代谢液培养法对大豆根瘤内生细菌进行棉花枯萎病菌抑菌性筛选,显微观察法研究筛选菌株引起病原菌菌丝变化,通过菌株培养特征、理化特性和16S r DNA序列同源性分析确定菌株系统发育地位,比色法测定DD174耐盐碱性,盆栽试验验证防病效果。【结果】经复筛和代谢液试验有5株拮抗性较强菌株,被作用病原菌菌丝畸形、细胞壁消失、自溶,菌丝基部加粗、分支增多,呈树根状;菌丝被菌苔包埋而溶解、断裂,菌丝末端球形膨大。对棉花枯萎病菌的抑制作用主要通过菌体产生胞外代谢物发挥作用。菌株DD174、DD176和DD179最相似菌株分别为Bacillus oceanisediminis H2T(GQ292772)和B.thuringiensis ATCC 10792T(AF290545),菌株DD165和DD166最相似菌株均为Stenotrophomonas maltophilia LMG 958T(X95923)。DD174能耐受6%盐浓度,p H 10生长良好,具有一定耐盐碱能力。DD174处理组防治效果达76.32%,其他防效均在62%以上,可作为棉花枯萎病的生防菌株资源。【结论】大豆根瘤内存在棉花枯萎病内生拮抗细菌,其中有些菌株具有一定耐盐碱能力,对棉花枯萎病病原菌及病害有一定抑菌和防病作用。     

西藏土壤中耐辐射阿氏芽胞杆菌T61的分离和鉴定

【目的】对分离自西藏土样的菌株T61进行分离、鉴定和UV辐射抗性分析。【方法】对菌株T61进行形态和生理生化鉴定;对16S r RNA基因进行克隆和测序,构建系统进化树;测定脂肪酸成分和GC含量,将T61与最相近种进行DNA-DNA杂交;测定T61的UV辐射抗性曲线。【结果】T61细胞杆状,长度约为2μm,直径约为1μm,革兰氏阳性,可产生内生孢子。G+C含量为38.02%。脂肪酸主要成分是C14:0 iso、C15:0 iso和C15:0 anteiso。16S r RNA基因与阿氏芽胞杆菌B8W22T和巨大芽胞杆菌IAM13418T相似度最高,分别达到99.93%和99.53%。DNA-DNA杂交分析表明,T61与阿氏芽胞杆菌B8W22T的相似度为81.4%,而与巨大芽胞杆菌IAM13418T的相似度只有50.3%。UV辐射抗性分析显示,T61 D10为100 J/m2,远高于辐射敏感的大肠杆菌K12和枯草芽孢杆菌等菌株。【结论】菌株T61是一株阿氏芽胞杆菌,命名为Bacillus aryabhattai T61,其对UV辐射具有较强的抗性。     

不同外源条件对4种白腐真菌溶藻效果的影响

【目的】评价白腐真菌Irpex lacteus XX-5、Trichaptum abietinum 1302BG、Ceriporia lacerata P2、Bjerkandera adusta XX-2处理铜绿微囊藻废水的应用潜力。【方法】采用分批次实验研究pH、温度、铜绿微囊藻浓度、金属离子、氮源、磷源对白腐真菌I. lacteus XX-5、T. abietinum 1302BG、C. lacerata P2、B. adusta XX-2溶解铜绿微囊藻的影响。【结果】在不同外源条件下,4种白腐真菌对铜绿微囊藻的抑制效果明显,均达60%以上。菌株C. lacerata P2和B. adusta XX-2受外源条件的影响很小,菌株C. lacerata P2的抑制率达70%以上,菌株B. adusta XX-2的抑制率达60%以上;菌株T. abietinum 1302BG、I. lacteus XX-5在不同外源条件下抑制率均会发生相应的变化,但抑藻率均可达60%以上。【结论】研究所使用的4种白腐真菌对抑制铜绿微囊藻具有较好的应用潜力,尤其是菌株C. lacerata P2和B. adusta XX-2。     

番茄灰霉病生防链霉菌筛选及鉴定

【背景】由灰葡萄孢侵染所致的番茄灰霉病是一类重要的真菌病害,生物防治具有环境友好、病原菌不易产生抗药性等特点,是果蔬灰霉病绿色防控的有效措施。【目的】筛选对番茄灰霉病具有防病作用且能促进番茄种子发芽的广谱拮抗性链霉菌,并明确该菌株种级分类地位。【方法】采用琼脂块法筛选拮抗番茄灰霉病菌的链霉菌菌株,采用对峙培养法和生长速率法检测菌株T22抑菌谱,通过产胞外酶活性检测、离体叶片防效和种子发芽试验明确该菌株的防病促生相关特性,根据形态学特征、生理生化特性和分子生物学方法对该菌株进行种类鉴定。【结果】从分离的56株放线菌中筛选到14株对番茄灰霉病菌具有拮抗效果的放线菌菌株,其中链霉菌T22对番茄灰霉病菌抑制作用最强,且具有较广抑菌谱,同时菌株T22具有产生纤维素酶和几丁质酶的能力。菌株T22无菌发酵滤液对番茄灰霉病菌、桃褐腐病菌、黄瓜枯萎病菌抑菌率分别为84.6%、81.5%和79.1%;其无菌发酵滤液原液对番茄灰霉病离体防效为55.1%;100倍稀释液处理番茄种子,胚轴、胚根和种子活力指数分别增加15.1%、29.7%和43.9%。根据形态学特征、生理生化特性和多基因聚类分析将链霉菌T22鉴定为白黑链霉菌(Streptomycesalboniger)。【结论】白黑链霉菌T22具有较强的抗真菌、产胞外酶、防病和促生活性,在番茄灰霉病生物防治中具有较好的开发应用潜力。     

辐射污染区盐爪爪根际可培养细菌群落组成及功能特性

【背景】我国西北某辐射污染区存在着丰富多样的耐辐射微生物资源,部分区域覆盖着耐盐植物盐爪爪,其根际存在明显的"离子岛"效应,开展其根际微生物相关研究对进一步挖掘污染区微生物资源及揭示盐爪爪的盐适应性和"离子岛"的形成具有重要的意义。【目的】分析辐射污染区盐爪爪根际微生物群落组成,挖掘潜在的微生物资源和功能特性。【方法】通过可培养方法,共选择了10种筛选培养基开展盐爪爪根际微生物的分离筛选,并对所获得的细菌进行了16S rRNA基因序列分子鉴定,进而进行相关菌株的抗逆特性、产酶特性和植物促生特性分析。【结果】分离获得的267株细菌归属于放线菌门(Actinobacteria)、变形杆菌门(Proteobacteria)、厚壁菌门(Firmicutes)等3个菌门中的20个属,发现潜在新种8个,其中放线菌门所含种属最丰富,说明盐爪爪根际存在着丰富的微生物多样性。相关抗逆性分析表明,分离得到的菌株70%以上可耐受10%NaCl,40%的菌株可耐受不同浓度的重金属胁迫。同时,研究获得了一批可产蛋白酶、脂肪酶、淀粉酶和纤维素酶的菌株以及植物促生菌株,可为相关酶制剂的筛选和微生物菌肥的研制提供丰富的材料。【结论】辐射污染区盐爪爪根际存在大量潜在的宝贵微生物资源,有待挖掘和开发。     

我国八种蜜环菌的木腐特性

为了揭示我国不同蜜环菌Armillaria的木腐特性,本研究以我国8个蜜环菌种为材料,采用蜜环菌液接种1 cm³的枹栎Quercus serrata木方,置于23℃下培养60 d和120 d,采用重量法、Klason法、硫酸水解法和盐酸水解法测定木材质量、纤维素含量、木质素含量和半纤维素含量,研究各蜜环菌株的木腐能力及差异性。结果表明,各蜜环菌种对枹栎木质量损失率排序为:CBS M(A.borealis)>CBS A(A.sinapina)=CBS J(A.qinii)=CBS H(A.bruneocystidia)=CBS F(A.sinensis)=CBS B(A.gallica)>CBS N(A.violacea)=CBS D(A.ostoyae);木质素的分解能力排序为:CBS M=CBS A=CBS J>CBS H=CBS B=CBS F>CBS N>CBS D;纤维素降解利用率排序为CBS H=CBS A>CBS B>CBS J>CBS F>CBS D>CBS M>CBS N;半纤维素分...     

两株海洋真菌的鉴定及其次级代谢产物抑制烟草花叶病毒及抗肿瘤活性

摘要：【目的】通过对2株活性海洋真菌发酵产物提取物抑制烟草花叶病毒和抗肿瘤活性进行研究,为进一步得到活性纯品化合物作为抗病毒及抗肿瘤的先导化合物奠定基础。【方法】菌株发酵产物的粗提物是通过甲醇浸取并在真空条件下蒸干得到的。粗提物中溶于水的部分为水溶性部分,不溶于水的部分为脂溶性部分。通过间接酶联免疫法检测样品抑制烟草花叶病毒的活性,通过四甲基偶氮唑盐微量酶反应比色法（MTT法）检测样品抗肿瘤活性,通过形态及ITS rDNA序列法进行菌株鉴定。【结果】两株海洋真菌抑制烟草花叶病毒活性和抗肿瘤的活性均较高。分子鉴定结果显示,两株真菌分别与Penicillium oxalicum 和 Neosartorya fischeri 的同源性极高。菌株0312F1发酵液的水溶性部分具有抗病毒及抗肿瘤活性,菌株1008F1发酵液的脂溶性部分具有抑制烟草花叶病毒活性,而水溶性部分具有抗肿瘤活性。【结论】菌株0312F1和菌株1008F1发酵液的提取物抑制烟草花叶病毒的活性部位不同,而抗肿瘤活性部位相同。菌株0312F1发酵液提取物的水溶性活性部位对肝癌细胞BEL-7404的抑制效果比对胃癌细胞SGC-7901的抑制效果明显,而菌株1008F1发酵液提取物的水溶性活性部位对胃癌细胞SGC-7901的抑制效果比对肝癌细胞BEL-7404的抑制效果明显。     

塔宾曲霉L-27菌株的分离鉴定及其发酵液除草潜力

【背景】微生物源天然产物是新农药研究开发的热点之一。【目的】从土壤中分离筛选代谢产物具有除草潜力的真菌菌株。【方法】培养皿滤纸法测定分离菌株发酵液对植物幼苗生长的抑制作用及抑制作用稳定性,显微观察结合rDNAITS序列分析鉴定菌株。【结果】在分离的30株土壤真菌中,L-27菌株发酵液对小麦幼苗生长抑制最显著,对根、茎抑制率分别为79.4%、67.3%。基于菌落形态、菌体显微观察和rDNA ITS基因序列分析,分离菌株L-27被鉴定为塔宾曲霉(Aspergillus tubingensis)。进一步测定发现,L-27菌株发酵液完全抑制反枝苋、马齿苋、稗草的幼苗生长,对圆叶牵牛幼苗根、茎的抑制率分别为100%、77.8%。L-27菌株发酵液对小麦幼苗生长的抑制作用表现出良好的热稳定性、酸碱稳定性和紫外光照射稳定性。发酵液在120°C加热20 min,根、茎生长抑制率分别为100%和73.8%;将发酵液调至pH 2.0-12.0并保持1 h,再调回初始pH值,对根、茎生长的抑制率均达100%;发酵液经紫外光照射5-240 min,抑制率分别为100%和84.3%-91.7%。【结论】分离的塔宾曲霉L-27菌株发酵液具有开发微生物源除草剂的潜力。     

恩拉霉素生产菌株的遗传改造

【目的】提高杀真菌素链霉菌发酵生产恩拉霉素的产量。【方法】利用定点突变技术,对恩拉霉素生产菌株杀真菌素链霉菌F1中影响细胞次级代谢及抗生素合成的核糖体S12蛋白的编码基因rps L进行改造,将第43位的赖氨酸(Lys)分别替换为天冬酰胺(Asn)和精氨酸(Arg),并对改造菌株L-M1(Asn43)和L-M2(Arg43)的生长特性、抗生素合成以及摇瓶发酵性能进行研究。【结果】与野生型菌株相比,改造菌株的生长特性及生理生化特性均发生了明显的改变:产孢周期明显缩短,野生型菌株在MS培养基中,28°C下需要培养5-7 d后才能产生孢子,而在相同条件下,改造菌株3 d后就能产生大量的孢子;恩拉霉素产量相对提高,摇瓶发酵条件下,改造菌株L-M1(Asn43)和L-M2(Arg43)的恩拉霉素产量分别可达到1 334 U/m L和1 456 U/m L,与野生型菌株F1相比分别提高了11.9%和22.1%。【结论】通过遗传改造,恩拉霉素的产量得到了提高,为其他位点的遗传改造提供了可行性。     

聚苹果酸生产菌出芽短梗霉CCTCC M2012223的全基因组测序及序列分析

【目的】解析出芽短梗霉CCTCC M2012223的基因组序列信息,分析其代谢产物聚苹果酸、黑色素、普鲁兰多糖合成相关基因,为深入研究遗传多样性和代谢工程改造提供序列背景信息。【方法】使用Illumina Hi Seq高通量测序平台对出芽短梗霉CCTCC M2012223菌株进行全基因组测序,并对测序数据进行序列拼接,基因预测与功能注释,COG/GO聚类分析,比较基因组学分析等。下载其他5株出芽短梗霉基因组序列,比较分析6株菌的种内同源基因、全基因组进化以及代谢产物合成相关基因。【结果】出芽短梗霉CCTCC M2012223基因组序列全长30756831 bp,GC含量47.49%,编码9452个基因。比较基因组分析表明出芽短梗霉CCTCC M2012223的基因组组装长度最长,6株菌的同源基因数达到7092个,普鲁兰多糖和聚苹果酸合成相关基因的蛋白序列有很高的保守性。出芽短梗霉CCTCC M2012223和Aureobasidium pullulans var.melanogenum亲缘关系最近,而这2株菌的黑色素合成相关基因的蛋白序列有一些插入和突变。【结论】本研究解析了出芽短梗霉CCTCC M2012223的基因组序列信息,获得黑色素、普鲁兰多糖和聚苹果酸合成相关基因,为后续的代谢机制解析和改造提供相关依据。     

The taxonomic position of Saccharomyces boulardii as evaluated by sequence analysis of the D1/D2 domain of 26S rDNA, the ITS1-5.8S rDNA-ITS2 region and the mitochondrial cytochrome-c oxidase II gene

A taxonomic study was carried out on eight strains of Saccharomyces boulardii. Morphological and physiological characteristics were consistent with those of Saccharomyces cerevisiae. Sequences of the D1/D2 domain of the 26S rDNA were identical for all strains examined and had a similarity value of 100% compared to sequences of the type strain of S. cerevisiae (CBS 1171T) and strain S288c. For all S. boulardii isolates was found the exact same ITS1-5.8S rDNA-ITS2 sequence, which displayed a close resemblance with the sequences published for S288c (99.9%), CBS 1171(T) (99.3%) and other S. cerevisiae strains. Sequence analysis of the mitochondrial cytochrome-c oxidase II gene (COX2) also resulted in identical sequences for the S. boulardii isolates and comparisons with available nucleotide sequences revealed close relatedness to strains of S. cerevisiae including S288c (99.5%) and CBS 1171(T) (96.6%). The electrophoretic karyotypes of the S. boulardii strains appeared quite uniform and although very typical of S. cerevisiae, they formed a cluster separate from strains of this species. The results of the present study strongly indicate a close relatedness of S. boulardii to S. cerevisiae and thereby support the recognition of S. boulardii as a member of S. cerevisiae and not as a separate species.     

2012–2015年江淮地区猪丹毒杆菌分离株血清型、spaA基因遗传进化及PFGE基因型分析

【目的】了解2012–2015年江淮地区猪丹毒杆菌分离株血清型分布、spaA基因遗传进化关系和基因分型特征。【方法】收集临床分离鉴定的42株猪丹毒杆菌,应用琼脂扩散沉淀实验、PCR扩增和序列分析技术、脉冲场凝胶电泳分型技术(PFGE)分别测定分离株的血清型、spaA基因遗传变异性及PFGE基因型。【结果】42株猪丹毒杆菌分离株血清型均为1a型;spaA基因与猪丹毒杆菌国内外参考株核苷酸序列相似性为98.5%–100%,分离株在第609 bp处出现T突变为G、769 bp处C突变为A,对应的氨基酸第203位Ile突变为Met、第257位Leu突变为Ile,为Met-203、Ile-257型;分离株形成8个PFGE基因型,相似度达88.8%–100%,优势基因型为ER2 (54.8%),弱毒疫苗G4T10和GC42株独立为同一个基因型。【结论】江淮地区致病猪丹毒杆菌流行血清型为1a型,spaA基因相似性高,分离株变异小、源于同一克隆系,Met-203、Ile-257型菌株致病力强,是江淮地区猪丹毒发生与流行的主要致病菌型。     

Diversity of basidiomycetous phylloplane yeasts belonging to the genus Dioszegia (Tremellales) and description of Dioszegia athyri sp. nov., Dioszegia butyracea sp. nov. and Dioszegia xingshanensis sp. nov

From approximately 200 basidiomycetous yeast isolates forming orange or orange-red colonies isolated from senescent leaves collected in different regions of China, 29 representative strains varying in their geographic distribution and ballistoconidium forming ability were selected for further phenotypic and molecular taxonomic studies. Sequence analysis of the large subunit (26S) rDNA D1/D2 domain and the internal transcribed spacer (ITS) region including 5.8S rRNA from the strains resulted in the recognition of seven Dioszegia species, including four described species, namely D. aurantiaca, D. fristingensis, D. hungarica and D. zsoltii var. zsoltii and D. zsoltii var. yunnanensis, and three undescribed species. The three new species are described as Dioszegia athyri sp. nov. (type strain: CB 159(T) = AS 2.2559(T) = CBS 10119(T)), Dioszegia butyracea sp. nov. (type strain: CB 261(T) = AS 2.2600(T) = CBS 10122(T)) and Dioszegia xingshanensis sp. nov. (type strain: HB 1.4(T) = AS 2.2481(T) = CBS 10120(T)) in the present study.     

DNA probes specific for the yeast species Debaryomyces hansenii: useful tools for rapid identification

We developed a rapid and sensitive identification method for the halotolerant yeast Debaryomyces hansenii, based on the hybridization of species-specific sequences. These sequences were first identified in a survey of D. hansenii strains by random amplification of polymorphic DNA (RAPD) as giving conserved bands in all isolates tested. Two such conserved RAPD products, termed F01pro and M18pro, were cloned from the type strain CBS 767. The specificity of these probes was assessed by hybridizing them to DNA from various species of yeasts commonly found in cheese. F01pro and M18pro hybridized to the DNA of all D. hansenii var. hansenii tested, but not to DNA of other yeast species including the closely related strain of D. hansenii var. fabryii CBS 789. Hybridization patterns of F01pro and M18pro on digested genomic DNA of D. hansenii indicated that the sequences were repeated in the genome of all D. hansenii var. hansenii tested, and gave distinct polymorphic patterns. The single F01pro probe generated 11 different profiles for 24 strains by restriction fragment length polymorphism, using one restriction enzyme. F01pro represents a new type of repeated element found in fungi, useful for both identification and typing of D. hansenii and, together with M18pro, simplifies the study of this species in complex flora.     

Species Composition of Cultivated and Noncultivated Bacteria from Short Filaments in an Icelandic Hot Spring at 88 degrees C

Samples of short pink-grayish filaments were collected from a hot spring in the Hengill area in southwestern Iceland at 85-88 degrees C, pH 6.9 and 1.7 mg/L sulfide. The species composition was studied by cloning and sequencing small subunit rRNA genes obtained by PCR amplifications from mat DNA. Using 98% sequence similarity as a cutoff value, a total of 5 bacterial operational taxonomic units (OTUs) and 6 archaeal OTUs were detected among 68 bacterial clones and 97 archaeal clones. Database matching showed that 80.5% of the archaeal sequences were 99% similar to Pyrobaculum islandicum and 14.5% were closest to the Korarchaeota clone sequence SRI306. About 87% of the bacterial sequences had the closest database match (99%) to the clone sequence SRI48 but were also found to be 99% identical with hydrogen-oxidizing strains previously isolated in this laboratory from hot springs in the same region. Out of 7 Thermus sequences, 4 were 100% identical to T. scotoductus NMX2 A.1 but 3 represented a new uncultivated Thermus species. Four different media, varying in organic nutrients and phosphate composition were used to isolate 81 aerobic thermophilic heterotrophs. Four isolates were Bacillus spp; but out of 77 Thermus isolates, 42 belonged to T. scotoductus and 35 to T. brockianus. T. scotoductus seemed to be preferably isolated on media low in nutrients and phosphate, whereas for T. brockianus it was the opposite. The T. scotoductus clones and isolates had 99-100% sequence similarity to each other. No T. brockianus sequences were found in the bacterial clone library.     

肉鸭养殖过程中发酵床垫料菌群结构变化的研究

【目的】探究发酵床使用时间和肉鸭粪便微生物对发酵床垫料菌群结构、总菌和大肠杆菌数量的影响。【方法】采集江苏某肉鸭发酵床养殖场内刚制作完成的发酵床垫料样品,及其饲养4批次、8批次后的垫料样品,同时采集各批次34日龄肉鸭粪便样品,采用变性梯度凝胶电泳技术(Denaturing gradient gel electrophoresis,DGGE)、16S rRNA基因序列分析和实时荧光定量PCR (Quantitative real-time PCR)技术对发酵床使用过程中垫料菌群结构进行定性和定量研究。【结果】0批次(D0)与4批次(D4)、8批次(D8)垫料菌群相似性分别为68.81%、70.82%,而4批次与8批次间垫料菌群的相似性则达81.93%,显著高于D4、D8与D0间相似性(P<0.05)。条带6、8 (最相似菌分别为Leqionella tunisiensis、Pedobacte bauzanensis)在3个时间点垫料菌群中均表现优势,且含量较为稳定;条带10 (最相似菌为Rummeliibacillus suwonesis)仅在2个重复使用垫料菌群中表现优势;条带12、13 (最相似菌分别是Psychrobacter sp. PRwf-1、Iamia majanohamensis)共同存在于垫料样和粪便样。肉鸭粪便中大肠杆菌的数量显著高于4批次、8批次垫料中的数量(P<0.05),与0批次垫料间差异不显著(P>0.05)。【结论】使用时间和肉鸭粪便微生物共同影响了发酵床垫料菌群结构和数量,菌群结构随使用时间的延长而趋于稳定。     

Molecular Characterization of Fusarium globosum Strains from South African Maize and Japanese Wheat

The fungus Fusarium globosum was first isolated from maize in South Africa and subsequently from wheat in Japan. Here, multiple analyses revealed that, despite morphological similarities, South African maize and Japanese wheat isolates of the fungus exhibit multiple differences. An amplified fragment length polymorphism-based similarity index for the two groups of isolates was only 45%. Most maize isolates produced relatively high levels of fumonisins, whereas wheat isolates produced little or no fumonisins. The fumonisin biosynthetic gene FUM1 was detected in maize isolates by Southern blot analysis but not in the wheat isolates. In addition, most of the maize isolates produced sclerotia, and all of them produced large orange to dark purple sporodochia in carrot agar culture, whereas wheat isolates did not produce either structure. In contrast, individual isolates from both maize and wheat carried markers for both mating type idiomorphs, which indicates that the fungus may be homothallic. However, a sexual stage of F. globosum was not formed under standard self-fertilization conditions developed for other homothallic species of Fusarium. The inability to produce the sexual stage is consistent with the high similarity of 87–100% and G _ST index of 1.72 for the maize isolates, which suggests that these isolates are undergoing asexual but not sexual reproduction. Together, the results suggest that the South African maize and Japanese wheat isolates of F. globosum are distinct populations and could be different species.     

印第安纳沙门氏菌对氯霉素类药物耐药性分析

[目的]调查鸡源沙门氏菌对氯霉素类药物的耐药特征和相关耐药基因的流行情况.[方法]从山东省部分地区鸡孵化场、养殖场、屠宰场分离样品进行沙门氏菌鉴定和药物敏感性试验;设计引物,对氯霉素类药物的耐药基因进行PCR扩增和序列分析.[结果]试验分离到印第安纳沙门氏菌,分离率为23.28％.孵化场、养殖场、屠宰场印第安纳沙门氏菌对氯霉素耐药率分别为50.00％、83.33％和93.30％,对氟苯尼考耐药率为83.33％、100％和100％,对甲砜霉素耐药率为63％、65％和77％.在80株氯霉素类耐药菌株中,54株检测到catA1基因,74株检测到floR基因,5株检测到cmlA基因.[结论]不同来源印第安纳沙门氏菌对氯霉素类药物耐药率存在差异,catA1和floR基因广泛存在于耐药菌株中.     

Cytochalasins from Phoma exigua var. Heteromorpha

Three further cytochalasins fromPhoma exigua var. heteromorpha, grown on wheat, were isolated and characterized by spectroscopic methods and by chemical correlation with cytochalasin B. They were identified as cytochalasin T, a new 24-oxa[14]cytochalasan, cytochalasin F and 7-O-acetylcytochalasin B, both isolated for the first time from this fungus. Cytochalasin F showed significant activity in the brine shrimp assay and on tomato seedling growth.