IDENTIFICATION OF ENDOPHYTIC BACTERIA ASSOCIATED WITH N2 FIXATION AND INDOLE ACETIC ACID SYNTHESIS AS GROWTH PROMOTERS IN CURCUMA ALISMATIFOLIA GAGNEP.

Endophytic bacteria carrying out dinitrogen (N₂) fixation and indole acetic acid (IAA) synthesis were firstly identified in C. alismatifolia, a globally important flower crop. Their potential as growth promoters to stimulate the rapid growth of host plant was also examined. It will be beneficial to reduce the propagation period of tissue culture plantlets, and also utilize as a biofertilizer for rhizome production in the field. Seven endophytic bacteria were isolated from the leaf, four isolates from the leaf base, and two from the rhizome. ECS203, a gram-negative bacterium with a round shape, showed the highest N₂ fixation at 4.2 nmol C₂H₄/10⁶ cells/hr, and ECS202 showed the highest IAA synthesis at 296 μL μg ^{? 1} protein. Three selected isolates of N₂-fixing and IAA synthesizing endophytic bacteria, i.e., ECS202, ECS203, and ECS204, isolated from the leaf base, were used to reinoculate Curcuma plantlets derived from tissue culture. Then, plants were grown in sterilized sand for 2 months and weekly supplied with N-free nutrient solution. Plant growth, colonization, nitrogen fixation, and IAA synthesis were measured at two months after planting. The inoculated plants clearly showed a better performance of plant growth and yield in terms of the plant height, plant weight, leaf area, and diameter of new rhizomes compared with uninoculated plants. The chlorophyll content and N concentration of leaves and roots also increased in inoculated plants. Endophytic bacteria from inoculated plants colonized the roots, rhizome, and leaf base. Partial sequence analysis using 16S rDNA indicated that the isolate ECS202 corresponded to Sphingomonas pseudosanguinis (99.2% similarity over 1,371 bp), ECS203 to Bacillus drentensis (99.4% similarity over 1,450 bp) and ECS204 to Bacillus methylotrophicus (99.9% similarity over 13,06 bp).     

Assessment of microbial diversity in the river trout Salmo trutta fario L. intestinal tract identified by partial 16S rRNA gene sequence analysis

ABSTRACT:   The microbial diversity of the intestinal tract content of the river trout from two Lithuanian rivers has been investigated by molecular methods: polymerase chain reaction amplification and sequencing of partial 16S rRNA genes. Predominant bacterial populations detected in the river trout intestinal tract from the Skroblus River were Rahnella (21%), from the Žeimena River, Aeromonas (41.7%) and Plesiomonas (22.9%). Buttiauxella agrestis, Budvicia aquatica, Erwinia persicinus , Yersinia mollaretii , Y. kristensenii , Y. rohdei , Moellerella wisconsensis , Obesumbacterium proteus , Pantoea cedenensis , Rahnella aquatilis , and Rahnella sp. from the Enterobacteriaceae family have been detected in the intestinal tract of freshwater salmonid fish for the first time.     

3种野鲮亚科鱼类16SrRNA基因序列分析

野鲮亚科(Labeoninae)隶属鲤形目(Cypriniformes)中的鲤科(Cyprinidae,约有26个属近300个种。为研究其在鲤科鱼类中的系统发育关系,以16S rRNA基因作为遗传标记进行鲤科鱼类的系统发育分析。通过PCR方法, 扩增了长度为361-362 bp的3种野鲮亚科鱼类的16S rRNA基因部分序列,序列比对得到364个排列位点,其中94个为信息位点,占全部位点的26.8%。用Mega 2.1软件的NJ法构建分子系统树,结果表明:野鲮亚科鱼类没有形成单系类群,野鲮亚科的鲮、角鱼与鲤亚科的鲤、鲫形成姐妹群,然后再与野鲮亚科的麦鲮和露斯塔野鲮聚在一起,说明鲮与鲤亚科鱼类具有较近的亲缘关系。     

Sequencing of 16S−23S rRNA internal transcribed spacer and its application in the identification of Nocardia seriolae by polymerase chain reaction

A method for the diagnosis of nocardiosis in yellowtail (Seriola quinqueradiata), using polymerase chain reaction (PCR), was developed in this study. Primers specific for Nocardia seriolae were synthesized based on the alignment of 16S?23S rRNA internal transcribed spacer region sequences of N. seriolae. The primers did not amplify specific PCR product from other fish pathogens. However, two and three fishes could be diagnosed as infected with N. seriolae by clinical signs and bacterial isolation. PCR amplification of N. seriolae by specific primers detected six infected fishes. Thus, the primers used in this study are useful in detecting nocardiosis in fish.     

Inter-specific variation of the mitochondrial r16S gene among silversides, “Peces Blancos”, (Atherinopsidae: Menidiinae) and its utilization for species identification

Analysis of 570 nucleotide sequences of the mitochondrial r16S gene of four species of silversides “peces blancos” (Chirostoma sp.) and of two euryhaline related species Membras martinica and Menidia menidia indicated variation that aided in development of a DNA-based method for species identification. The nucleotide sequence data showed levels of inter-generic genetic variation that ranged from 3.3–7.9% and from 1.06 to 1.6% at the inter-specific level. The variation observed allowed the identification of 18 diagnostic restriction enzymes that in any combination of two or three could aid in the diagnosis of species of “peces blancos”; six of these enzymes could also discriminate between the genera Membras and Menidia; the enzymes AseI, CviAII and FatI discriminate the genus Membras from Chirostoma; and the combination of any of the enzymes BsaAI, CviAII, FatI or HpyCH4IV discriminate Menidia from the “peces blancos”. PCR-RFLP analysis of amplified mitochondrial r16S fragments of 90 un-identified “peces blancos” from Lake Patzcuaro utilizing the restriction enzymes HpyCH41V, TaqI, BsmF1 and BbvI allowed us to diagnose unambiguously cultivated Chirostoma estor and C. humboldtianum in juvenile and adult stages. The use of a non-invasive method to PCR-amplify specific DNA markers from live brood stocks suggests use of this tool for identification of endangered or threatened species.     

Salmonid gill bacteria and their relationship to amoebic gill disease

16S ribosomal RNA gene analysis was used to assess the bacterial community associated with Atlantic salmon, Salmo salar L., gills which were either affected by amoebic gill disease (AGD) or were AGD-negative, in order to determine the role that bacteria may play in the development of AGD. AGD-positive specimens were either infected in the laboratory with Neoparamoeba pemaquidensis, the causative agent of AGD, or were obtained from commercial salmon cages. Samples from laboratory fish maintained in sea water possessed a marine-type community while field samples which had been treated by a series of freshwater baths possessed a more diverse community which included variable proportions of different bacterial ecotypes, including groups typically associated with soil, skin surfaces and faeces. Samples from fish infected with AGD in the laboratory and a sample from one of two salmon cage fish specimens were dominated by a phylotype belonging to the strictly marine bacterial genus Psychroserpens (family Flavobacteriaceae, phylum Bacteroidetes). The phylotype was not detected in any of the AGD-negative samples or in one of two AGD-positive samples obtained from fish subjected to temporary freshwater immersion. The possibility of certain Psychroserpens species as potential opportunistic pathogens associated with salmonid AGD is proposed.     

农杆菌介导将Pti5-VP16基因导入烟草的研究

番茄Pti5基因位于Pto基因下游,Pti5基因编码的蛋白作为转录调控因子能够增强病程相关蛋白(PR蛋白)基因的表达,从而提高其抗病性。以烟草叶片为外植体,通过根癌农杆菌叶盘转化法,将Pti5-VP16基因导入烟草SRI中,经卡那霉素筛选,获得了27株抗性植株,经PCR检测,表明抗性植株中整合了Pti5-VP16基因。然后通过病原菌Pseu-domonassyringaepv.tabaci的接种来检测转基因烟草植株的抗病性。     

奶牛乳腺炎大肠杆菌PCR的检测

通过对内蒙古呼和浩特地区分离3株奶牛乳腺炎大肠杆菌16S-23S rRNA间隔区的PCR检测、基因测序和序列比较分析,结果表明:分离菌株12C与参考菌株的同源率为99.9%,DG-25A和DG-23A与参考菌株的同源率为98.9%,3株分离菌株的同源性高。应用PCR检测奶牛乳腺炎大肠杆菌的方法简便、快速、特异,该方法也可广泛用于乳房炎其他病原菌的检测。     

花生新品种濮花16号的选育

濮花16号高产早熟,株型直立,百果重248.7g,百仁重98.0g,出米率72.55%,生育期110～120d,通过多年试验的方差分析和回归分析,表明濮花16号是一个丰产、稳产、适应性强的品种.     

玉米弯孢菌叶斑病菌拮抗链霉菌的分离及鉴定

从吉林省图们市地区土壤中分离得到1株对玉米弯孢菌叶斑病(CurvularialunataWaker)有拮抗作用的链霉菌菌株。研究其拮抗性表明,对革兰氏阴性菌、革兰氏阳性菌和多种病源真菌都有拮抗作用。根据形态特征、培养特征、生理生化特性及16SrDNA序列等方面的多项分类研究,确定其属于链霉菌属,并被命名为StreptomycestumenensisBPS2。该菌株在大多数培养基上生长良好,基内菌丝无横隔,不断裂,气生菌丝体形成孢子链,孢子丝呈波曲或直形。