首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
Two populations of Rivularia‐like cyanobacteria were isolated from ecologically distinct and biogeographically distant sites. One population was from an unpolluted stream in the Kola Peninsula of Russia, whereas the other was from a wet wall in the Grand Staircase‐Escalante National Monument, a desert park‐land in Utah. Though both were virtually indistinguishable from Rivularia in field and cultured material, they were both phylogenetically distant from Rivularia and the Rivulariaceae based on both 16S rRNA and rbcLX phylogenies. We here name the new cryptic genus Cyanomargarita gen. nov., with type species C. melechinii sp. nov., and additional species C. calcarea sp. nov. We also name a new family for these taxa, the Cyanomargaritaceae.  相似文献   

2.
Five strains of Drouetiella (ACKU666, 667, 668, 669 and 670) were isolated from gravels in water, stone monument and coastal mudflat in Korea, and were studied using morphological and molecular traits. All five strains had thin and simple trichomes and exhibited false branching. From these strains, four strains (ACKU666, 667, 668 and 669) exhibited similar cell lengths with reddish–brown colored cells such as Drouetiella lurida. The 16S rRNA gene phylogeny showed the four strains formed a clade with Drouetiella lurida, and their DNA similarity was calculated to be 99.1–100%. The color of strain ACKU670 appeared to be in bright blue–green color like Drouetiella fasciculata, and their thylakoids showed a parietal arrangement, which is a characteristic feature of the family Oculatellaceae. Strain ACKU670 turned out to be a sister clade to the D. lurida according to the phylogenetic analysis of the 16S rRNA gene. The 16–23S rRNA internal transcribed spacer secondary folding structure (D1–D1′, Box-B and V3 helices) confirmed the uniqueness of strain ACKU670, therefore indicating differences from the related species. Considering all the results, we described our strain ACKU670 as Drouetiella epilithica sp. nov. in accordance with the International Code of Nomenclature for Algae, Fungi and Plants.  相似文献   

3.
Genotypic diversity of several cyanobacterial strains mostly isolated from marine or brackish waters, belonging to the genera Geitlerinema and Spirulina, was investigated by amplified 16S ribosomal DNA restriction analysis and compared with morphological features and response to salinity. Cluster analysis was performed on amplified 16S rDNA restriction profiles of these strains along with profiles obtained from sequence data of five Spirulina-like strains, including three representatives of the new genus Halospirulina. Our strains with tightly coiled trichomes from hypersaline waters could be assigned to the Halospirulina genus. Among the uncoiled strains, the two strains of hypersaline origin clustered together and were found to be distant from their counterparts of marine and freshwater habitat. Moreover, another cluster, formed by alkali-tolerant strains with tightly coiled trichomes, was well delineated. Received: 14 May 2002 / Accepted: 22 July 2002  相似文献   

4.
Five cyanobacterial strains exhibiting Nostoc-like morphology were sampled from the biodiversity hotspots of the northeast region of India and characterized using a polyphasic approach. Molecular and phylogenetic analysis using the 16S rRNA gene indicated that the strains belonged to the genera Amazonocrinis and Dendronalium. In the present investigation, the 16S rRNA gene phylogeny clearly demarcated two separate clades of Amazonocrinis. The strain MEG8-PS clustered along with Amazonocrinis nigriterrae CENA67, which is the type strain of the genus. The other three strains ASM11-PS, RAN-4C-PS, and NP-KLS-5A-PS clustered in a different clade that was phylogenetically distinct from the Amazonocrinis sensu stricto clade. Interestingly, while the 16S rRNA gene phylogeny exhibited two separate clusters, the 16S–23S ITS region analysis did not provide strong support for the phylogenetic observation. Subsequent analyses raised questions regarding the resolving power of the 16S–23S ITS region at the genera level and the associated complexities in cyanobacterial taxonomy. Through this study, we describe a novel genus Ahomia to accommodate the members clustering outside the Amazonocrinis sensu stricto clade. In addition, we describe five novel species, Ahomia kamrupensis, Ahomia purpurea, Ahomia soli, Amazonocrinis meghalayensis, and Dendronalium spirale, in accordance with the International Code of Nomenclature for algae, fungi, and plants (ICN). Apart from further enriching the genera Amazonocrinis and Dendronalium, the current study helps to resolve the taxonomic complexities revolving around the genus Amazonocrinis and aims to attract researchers to the continued exploration of the tropical and subtropical cyanobacteria for interesting taxa and lineages.  相似文献   

5.
Stenomitos terricola FBCC-A190 was collected from soils around the trees of Mt. Gwanggyo, located in Yeongtong-gu, Suwon-si, Gyeonggi-do. S. terricola FBCC-A190 is a thin and simple filament with a cell length that is longer than its width. It has a thin and firm sheath, exhibiting a blue-green color. Species belonging to genus Stenomitos is semi-cryptic species with slight morphological differences from each other. They were confirmed as Stenomitos species by analysis using 16S rRNA and 16S–23S ITS. A monophyletic cluster was formed with the previously reported genus Stenomitos, with 16S rRNA gene sequences sharing similarities of 95.9–97.9% except for S. pantisii TAU-MAC 4318. In addition, 16S–23S ITS gene sequencing showed tRNAAla, tRNAIle and V2, similar to the previously reported genus Stenomitos. From these results, Stenomitos terricola sp. nov. was proposed as a new species belonging to genus Stenomitos.  相似文献   

6.
A taxonomic reevaluation of the paralytic shellfish toxin (saxitoxins) producing cyanobacterium Aphanizomenon flos‐aquae Ralfs ex Born. & Flah. LMECYA31 was done using morphology and 16S rRNA gene sequences. We found that strain LMECYA31 was incorrectly identified as Aph. flos‐aquae based on (a) lack of bundle formation in trichomes, (b) shape of terminal cells in the trichomes, (c) lower similarity (<97.5%) in the 16S rRNA gene sequences relative to those of Aph. flos‐aquae, and (d) comparison within a phylogenetic tree of 16S rRNA gene sequences. The shape of the terminal trichome cells and the shape and size of the vegetative cell, heterocyst, and akinete in strain LMECYA31 match characters of Aph. issatschenkoi (Ussachew) Proschkina‐Larvernko. 16S rRNA gene sequences and phylogenetic clusters constructed from 16S rRNA gene sequences support our conclusion that strain LMECYA31 should be Aph. issatschenkoi.  相似文献   

7.
Historically, the genus Calothrix included all noncolonial, tapered, heterocytous filaments within the cyanobacteria. However, recent molecular phylogenies show that “Calothrix” defined in this sense represents five distinct clades. The type species of Calothrix is marine, with solitary basal heterocytes, no akinetes, and distal ends tapering abruptly into short hairs. We examined the morphology and phylogeny of 45 tapering cyanobacteria in the Rivulariaceae, including freshwater and marine representatives of both Calothrix (35 strains) and its sister taxon Rivularia (10 strains). The marine Calothrix fall into two lineages, but we lack the generitype and so cannot identify the clade corresponding to the type species. The freshwater and soil Calothrix fall into the C. parietina clade and are characterized by having a basal heterocyte, no akinetes, and gradual tapering—but not into a long hyaline hair. Macrochaete gen. nov. is a freshwater taxon sister to the Calothrix lineages but clearly separated from Rivularia. The species in this genus differ morphologically from Calothrix by their ability to produce two heteromorphic basal heterocytes and specific secondary structures of the 16S–23S ITS. An additional feature present in most species is the presence of a distal, long hyaline hair, but this character has incomplete penetrance due to its expression only under specific environmental conditions (low phosphate), and in one species appears to be lost. We recognize three species: M. psychrophila (type species) from cold environments (high mountains, Antarctica), M. santannae from wet walls of subtropical South America, and M. lichenoides, a phycobiont of lichens from Europe.  相似文献   

8.
Li  Renhui  Carmichael  Wayne W.  Liu  Yongding  Watanabe  Makoto M. 《Hydrobiologia》2000,438(1-3):99-105
The taxonomy of Aphanizomenon flos-aquae strain NH-5, a producer of cyanotoxins, was re-evaluated by comparison with six other Aphanizomenon strains using morphological characteristics and 16S rRNA gene sequences. Strain NH-5 was concluded to be improperly identified as Aph. flos-aquae based upon (1) lack of bundle formation in the trichomes, (2) location of akinetes next to heterocytes, (3) lower similarities (less than 97.5%) in the 16S rRNA gene sequences relative to Aph. flos-aquae strains, and (4) comparison within a phylogenetic tree constructed from 16S rRNA gene sequences. The Aphanizomenon strains investigated in this study are classified to four morphological groups as described by the classical taxonomy of Komárek & Kovácik (1989). This classification was supported from the phylogenetic results of 16S rRNA gene sequences. This study also discusses the generic boundaries between Aphanizomenon and Anabaena.  相似文献   

9.
Two untapered, heterocytous species were observed and collected from the intertidal and supratidal zones of the Mexican coastline of the Pacific Ocean near Oaxaca and from the Gulf of Mexico. These populations were highly similar in morphology to the freshwater taxon Petalonema incrustans in the Scytonemataceae. However, 16S rRNA sequence data and phylogenetic analysis indicated that they were sister taxa to the epiphyllic, Brazilian species Phyllonema aveceniicola in the Rivulariaceae, described from culture material. While genetic identity between the two new species was high, they differed significantly in morphology, 16S rRNA gene sequence identity, and sequence and structure of the 16S–23S ITS region. Their morphology differed markedly from the generitype of the previously monotypic Phyllonema, which has tapered, heteropolar, single‐false branched trichomes with very thin or absent sheath. The two new species, Phyllonema ansata and Phyllonema tangolundensis, described from both culture and environmental material, have untapered, isopolar, geminately false branched trichomes with thick, lamellated sheaths, differences so significant that the species would not be placed in Phyllonema without molecular corroboration. The morphological differences are so significant that a formal emendation of the genus is required. These taxa provide a challenge to algal taxonomy because the morphological differences are such that one would logically conclude that they represent different genera, but the phylogenetic evidence for including them all in the same genus is conclusive. This conclusion is counter to the current trend in algal taxonomy in which taxa with minor morphological differences have been repeatedly placed in separate genera based primarily upon DNA sequence evidence.  相似文献   

10.
Partial 16S ribosomal RNA sequences from five marine oscillatoriacean strains with narrow trichomes were determined by a dideoxynucleotide-termination method. A phenogram was constructed by a distance matrix method including a bootstrap analysis. In addition, a consensus tree was built using cladistic analysis. The results were largely congruent and indicate that the five strains belong to two different lineages. The first lineage groups four phycoerythrin-producing strains with the strain PCC7375 (“Phormidium ectocarpi Gomont”). The second cluster groups strain PCC7105 (“Oscillatoria williamsii Drouet”) with the previously studied strain Microcoleus 10mfx. Comparisons to morphological data are made and the taxonomic level of the separations is estimated.  相似文献   

11.
12.
A polyphasic taxonomic study was performed on seven Bacillus-like bacteria isolated from three hypersaline and alkaline lakes located in China, Kenya and Tanzania. All strains were moderately halophilic and alkaliphilic, Gram positive, motile rods. The DNA G+C content from the seven isolates ranged from 42.2 to 43.4 mol% and their major fatty acid was anteiso-C15:0. Strain CG1T, selected as representative strain of the isolates, possesses meso-diaminopimelic acid in the cell wall peptidoglycan, MK-7 as the predominant menaquinone and diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine as the major polar lipids. Comparative 16S rRNA gene sequence analysis indicated that the isolates belonged to the genus Bacillus. The seven isolates shared 97.7–99.9% 16S rRNA gene sequence similarity, and formed a branch that was distinct from the type strains of the recognized species of the genus Bacillus. They were most closely related to Bacillus agaradhaerens DSM 8721T (92.6–93.8% 16S rRNA sequence similarity). DNA–DNA hybridization values between the seven isolates were 85–100%. According to the polyphasic characterization, the strains represent a novel species, for which the name Bacillus locisalis sp. nov. is proposed. The type strain is CG1T (CCM 7370T = CECT 7152T = CGMCC 1.6286T = DSM 18085T).  相似文献   

13.
【目的】为了解云南腾冲小空山火山谷土壤中可培养芽胞杆菌种类分布特征。【方法】采用可培养手段对小空山火山谷阳坡、谷底和阴坡土壤中的芽胞杆菌进行分离培养,根据16S rRNA基因序列同源性对分离菌株进行鉴定,并分析系统发育地位。利用Canoco5软件分析采样点芽胞杆菌种类分布特征与土壤样品理化性质的相关性。【结果】从火山谷土壤样品中共分离获得180株芽胞杆菌,16S rRNA基因测序鉴定结果表明分离菌株隶属于芽胞杆菌纲2个科(芽胞杆菌科和类芽胞杆菌科)、6个属、34个种,其中芽胞杆菌属(Bacillus) 11个种,类芽胞杆菌属(Paenibacillus) 14个种,短芽胞杆菌属(Brevibacillus)3个种,赖氨酸芽胞杆菌属(Lysinibacillus)4个种,嗜冷芽胞杆菌属(Psychrobacillus)1个种和绿芽胞杆菌属(Viridibacillus)2个种,其中7个菌株与其最近模式菌株16SrRNA相似性低于种的界定阈值(98.65%),为芽胞杆菌潜在新物种。优势属为芽胞杆菌属和类芽胞杆菌属,优势种为蕈状芽胞杆菌(Bacillusmycoides),图瓦永芽胞杆菌(Bacillustoyonensis),蜡状芽胞杆菌(Bacilluscereus),解木糖赖氨酸芽胞杆菌(Lysinibacillusxylanilyticus),蜂房类芽胞杆菌(Paenibacillusalvei)和沙地绿芽胞杆菌(Viridibacillus arenosi)。其中16个种分离自阳坡,29个种分离自阴坡,9个种分离自谷底,三者共同种类为6种。阳坡、谷底和阴坡的芽胞杆菌种群分布Bray-Curtis相似性为62.4%,多样性分析结果表明,Shannon指数(H′)大小次序为阴坡阳坡谷底。环境因子分析发现,芽胞杆菌种群分布多样性特征与其土壤的海拔高度、碳氮比和硫含量呈负相关,而和碳源和氮源含量呈正相关。【结论】从以上结果得出,云南腾冲火山谷有着较为丰富的芽胞杆菌资源,且还存在可分离培养的芽胞杆菌的潜在新物种,为利用火山微生物资源提供了保障。  相似文献   

14.
The ecology of Chroothece was studied in the highly calcareous Río Chícamo, south-east Spain, in order to explain its success there, but rarity elsewhere. The river, which originates mainly from an underground aquifer, has water with high conductivity, sulphate and nitrate but low phosphate concentrations, the latter mainly organic. Chroothece occurs in mats and in lobed colonies reaching 4 cm in the broadest dimension. The colony surface consists of one layer of cells, each of which is attached to a stalk, which dichotomizes when the cell divides; stalks often extend to the colony base. The central region of many mat cells and almost all colony cells has a yellow to orange-brown colour, associated with the numerous lipid droplets densely covering the surface of the pyrenoid and arms of the star-shaped chloroplast. Field material and laboratory isolates indicate that stalk formation occurs under moderate P limitation and both stalks and cell sheath show high phosphatase activities. This also occurred in a culture collection strain maintained for 30 years in a very P-rich medium, but then transferred to a moderately P-limiting medium (c. 0.9 mg l?1). We suggest that colony formation is initiated by aggregation of motile cells following P pulses in the water. Comparisons are made with Rivularia, a competitor in this nitrate-rich river, in spite of being a N2-fixer. One difference is that Chroothece cells lie at the periphery of the colonies and are therefore exposed to maximum sunlight, whereas Rivularia trichomes grow inside colonies with photoprotection by scytonemin. However, the ability to withstand heavy grazing pressure may be an especially important factor favouring Rivularia here.  相似文献   

15.
A new filamentous cyanobacterial species of the genus Brasilonema was isolated from the island of Oahu, Hawaii. The taxon is distinguished from the seven other species in the genus by attenuation of trichomes, and is here described as Brasilonema angustatum sp. nov. It possesses the cytoplasmic kerotimization and reddish‐brown coloration of several species in the genus. Phylogenetic analysis based on 16S rRNA gene sequence shows B. angustatum within a highly supported clade containing all sequenced Brasilonema species. We compared the secondary structure of the 16S–23S ITS regions for B. octagenarum and B. angustatum. The structurally conservative D1–D1′ and V3 helices show similar motifs between the two taxa, but differ structurally and in sequence, providing additional justification for erection of the new species. The Box‐B helix has identical secondary structure. The existence of tapering in a Brasilonema species is unique in this genus, and requires modification of the current concept of the genus Brasilonema, which was described as being unattenuated. Our phylogenetic evidence supports the hypothesis that tapering has developed repeatedly in separate cyanobacterial lineages and lacks the taxonomic significance once assumed by early workers.  相似文献   

16.
【目的】本试验以源自呼伦贝尔地区的优势蜱种草原革蜱为材料,从其体内分离得到可疑细菌,应用常规方法和分子生物学方法对该菌株进行分离及鉴定,并对其致病性进行探索,为内蒙古地区蜱虫生物多样性和环境相关性研究奠定了基础。【方法】首先,通过形态学观察,生理生化试验、药物敏感试验以及16S r RNA序列分析,并构建系统发育树,确定该菌株的分类地位;其次对昆明小鼠进行致病性实验。【结果】该菌株革兰氏染色呈G+杆菌,在高盐培养基(5%Na Cl)和p H为9的碱性培养基中生长良好;该菌对不同糖类发酵能力非常有限,只利用部分糖类(如西蒙氏枸橼酸盐试验结果为阳性)产气,但是不产酸;对个别化学药(如环丙沙星)和多数抗生素(如复方新诺明、庆大霉素、红霉素及头孢噻肟等)显示为敏感,而对抗生素卡那霉素和阿莫西林表现为耐药性;经16S r RNA基因序列和系统发育树分析发现,该菌株与GenBank数据库中已注册的多株Oceanobacillus oncorhynchi的同源性为99%以上;该菌在血平板溶血试验中呈现出不完全α溶血,而感染昆明小鼠,观察7 d无明显致病性。【结论】本试验首次分离鉴定了一株蜱源性O.oncorhynchi,并对上述菌株重新命名为O.oncorhynchi IMH,并在Gen Bank中进行注册(LC213016.1),更加丰富了Gen Bank中相关数据。  相似文献   

17.
A new Phormidium‐like genus was found during an investigation of Oscillatoriales diversity in Brazil. Eight aerophytic populations from south and southeastern regions were isolated in monospecific cultures and submitted to polyphasic evaluation. The populations presented homogeneous morphology with straight trichomes, not attenuated, and apical cell with thickened cell wall. Phylogenetic analyses based on 16S rRNA gene sequences showed that these populations, plus the Brazilian strain Phomidium sp. B‐Tom from GenBank, formed a highly supported and distinctive clade, which corresponds to the new genus Pycnacronema, comprising six new species: P. brasiliensis (type species), P. arboriculum, P. conicum, P. marmoreum, P. rubrum, and P. savannensis. These results were confirmed and supported by rpoC1 and rbcL genes evaluated independently and by the concatenated analysis of 16S rRNA, rpoC1 and rbcL genes (for all species but P. savannensis). Secondary structures of the D1‐D1′, box‐B, and V3 regions of the internal transcribed spacer were informative at specific level, being conserved in P. brasiliensis and variable among the other strains, also confirming the phylogenetic analyses. The generic name and specific epithets of the new taxa are proposed under the provisions of the International Code of Nomenclature of algae, fungi, and plants.  相似文献   

18.
Abstract

Lake Tuz, the largest hypersaline lake in Turkey, has a great variety of microbial communities that adapted to its extreme environment and produce many industrially important compounds such as photosensitive bacteriorhodopsins. So far, the information about the bacteriorhodopsin-producing haloarchaea species of the lake is still limited. In the present study, archaeal bacteriorhodopsin producers were isolated from three locations of the lake. Their bacteriorhodopsin-producing capability was validated by the purification and SDS-PAGE analysis of the delipidated bacteriorhodopsin molecule. The active isolates were identified by the sequencing of partial 16S rDNA gene regions. According to the results, 11 bacteriorhodopsin-producing isolates grouped in Halobacterium salinarum (4), Halobacterium sp. (3), Haloarcula salaria (2), Haloarcula sp. (1) and Halorubrum sp. (1). Our research demonstrated that Lake Tuz is an important natural source of bacteriorhodopsin-producing haloarchaea and the isolates can be valuable for the related technological applications.  相似文献   

19.
Three novel strains in Calotrichaceae from tropical habitats were isolated and characterized with regard to their morphology, phylogenetic placement, and secondary structures of conserved domains in the 16S-23S internal transcribed spacer (ITS). The strains fell into two clades formerly identified as Calothrix from freshwater and brackish habitats. Based on both morphology and ecology, they differed from the type species of Calothrix, C. confervicola, which is marine, has wide trichomes with short cells, and narrows abruptly to a hyaline hair. The first clade grouped species with heteropolar filaments widened at the base and narrowed gradually toward the apex but not ending in a hair, with basal heterocytes that are formed in series as the apically placed heterocytes senesce; this clade is being named Fulbrightiella gen. nov., with two named species, F. bharadwajae sp. nov. and F. oahuensis sp. nov. The second clade was comprised of a single species with isopolar trichomes that are untapering as hormogonia, but which widen midfilament and taper toward both ends following growth. These trichomes develop pairs of heterocyte mid-filament, causing fragmentation into heteropolar trichomes with basal heterocytes and ends that taper, but not to a hair. This clade consists of a single species at present, Sherwoodiella mauiensis. With this action, four clades in the Calotrichaceae have been named: Macrochaete, Dulcicalothrix, Fulbrightiella, and Sherwoodiella. Calothrix sensu stricto is truly marine, morphologically distinct, and unsequenced; finding and sequencing the generitype for Calothrix remains as the most important and unfinished task in the revision of the Calotrichaceae.  相似文献   

20.
The taxonomic position of an actinomycete isolated from soil was evaluated using a polyphasic approach. The organism, strain J72, was found to have chemical and morphological properties consistent with its assignment to the genus Gordonia. A nearly complete 16S rDNA sequence of the strain was determined by direct sequencing of the amplified gene. The tested strain formed a distinct phylogenetic line within the evolutionary radiation occupied by the genus Gordonia and was most closely related to G. polyisoprenivorans DSM 44302T. The phenotypic profile of strain 372 readily distinguishes it from representatives of the validly described species of Gordonia. The combined genotypic and phenotypic data show that strain J72 merits recognition as a new species of Gordonia. The name proposed for the new species is Gordonia sinesedis; the type strain is J72T (= DSM 44455T = NCIMB 13802T). This revised version was published online in June 2006 with corrections to the Cover Date.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号