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1.
Phylogenetic comparison has been done among the selected heterocystous cyanobacteria belonging to the sections IV and V. The hierarchical cluster analysis based on antibiotics sensitivity showed a distant relationship between the members of Nostocales and Stigonematales. Thus, multiple antibiotic resistance pattern used as marker provide easy, fast, and reliable method for strain discrimination and genetic variability. However, morphological, physiological (both based on principal component analysis) and biochemical analysis grouped true branching cyanobacteria along with the members of section IV. Molecular analysis based on 16S rRNA gene sequences revealed that Hapalosiphon welwitschii and Westiellopsis sp. were grouped in cluster I whereas Scytonema bohnerii, a false branching genera showed a close proximity with Calothrix brevissima in cluster II. Cluster III of clade 2 included Nostoc calcicola and Anabaena oryzae which proved the heterogeneity at the generic level. Cluster IV the largest group of clade 2 based on 16S rRNA gene sequences includes six strains of the genera Nostoc, Anabaena, and Cylindrospermum showing ambiguous evolutionary relationship. In cluster IV, Anabaena sp. and Anabaena doliolum were phylogenetically linked by sharing 99% sequence similarity. Probably, they were of the same genetic makeup but appear differently under the diverse physiological conditions. Section IV showed polyphyletic origin whereas section V showed monophyletic origin. Results suggested that either morphological or physiological or biochemical or molecular attribute is not sufficient to provide true diversity and phylogeny of the cyanobacteria at the generic level and thus, a polyphasic approach would be more appropriate and reliable. 相似文献
2.
In order to assess phylogeny, population genetics, and approximation of future course of cyanobacterial evolution based on nifH gene sequences, 41 heterocystous cyanobacterial strains collected from all over India have been used in the present study. NifH gene sequence analysis data confirm that the heterocystous cyanobacteria are monophyletic while the stigonematales show polyphyletic origin with grave intermixing. Further, analysis of nifH gene sequence data using intricate mathematical extrapolations revealed that the nucleotide diversity and recombination frequency is much greater in Nostocales than the Stigonematales. Similarly, DNA divergence studies showed significant values of divergence with greater gene conversion tracts in the unbranched (Nostocales) than the branched (Stigonematales) strains. Our data strongly support the origin of true branching cyanobacterial strains from the unbranched strains. 相似文献
3.
Contiguous organization of nitrogenase genes in a heterocystous cyanobacterium 总被引:7,自引:0,他引:7
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The organization of the three structural nitrogen fixation (nif) genes that encode nitrogenase (nif K and nif D) and nitrogenase reductase (nif H) have been examined in a number of cyanobacteria. Hybridization of Anabaena 7120 nif gene probes to restriction endonuclease-digested genomic DNA has shown (a) that cyanobacteria incapable of N2 fixation have no regions of DNA with significant homology to the three nif probes, (b) that Pseudanabaena sp., a nonheterocystous cyanobacterium, has a contiguous nif KDH gene cluster, and (c) that in contrast with other heterocystous cyanobacteria, Fischerella sp. has a contiguous nif KDH gene cluster. 相似文献
4.
Toxic freshwater cyanobacteria form harmful algal blooms that can cause acute toxicity to humans and livestock. Globally distributed, bloom-forming cyanobacteria Planktothrix either retain or lose the mcy gene cluster (encoding the synthesis of the secondary metabolite hepatotoxin microcystin or MC), resulting in a variable spatial/temporal distribution of (non)toxic genotypes. Despite their importance to human well-being, such genotype diversity is not being mapped at scales relevant to nature. We aimed to reveal the factors influencing the dispersal of those genotypes by analyzing 138 strains (from Europe, Russia, North America and East Africa) for their (i) mcy gene cluster composition, (ii) phylogeny and adaptation to their habitat and (iii) ribosomally and nonribosomally synthesized oligopeptide products. Although all the strains from different species contained at least remnants of the mcy gene cluster, various phylogenetic lineages evolved and adapted to rather specific ecological niches (for example, through pigmentation and gas vesicle protein size). No evidence for an increased abundance of specific peptides in the absence of MC was found. MC and peptide distribution rather depended on phylogeny, ecophysiological adaptation and geographic distance. Together, these findings provide evidence that MC and peptide production are primarily related to speciation processes, while within a phylogenetic lineage the probability that strains differ in peptide composition increases with geographic distance. 相似文献
5.
Pavel Hrouzek Tomáš Řezanka Jitka Jezberová Klára Řeháková Daniel Hisem Jaroslava Komárková 《Journal of phycology》2011,47(5):1152-1163
The genera Dolichospermum (Ralfs ex Bornet et Flahault) Wacklin, L. Hoffm. et Komárek and Sphaerospermopsis Zapomělová, Jezberová, Hrouzek, Hisem, K. ?eháková et Komárk.‐Legn. represent a highly diversified group of planktonic cyanobacteria that have been recently separated from the traditional genus Anabaena Bory ex Bornet et Flahault. In this study, morphological diversity, phylogeny of the 16S rRNA gene, production of fatty acids, and secondary metabolite profiles were evaluated in 33 strains of 14 morphospecies isolated from the Czech Republic. Clustering of the strains based on 16S rRNA gene sequences corresponded to wider groups of species in terms of morphology. The overall secondary metabolite and fatty acid profiles, however, were not correlated to each other and neither were they correlated to the 16S rRNA phylogeny nor the morphology of the strains. Nevertheless, a minor part of the detected secondary metabolites (19% of all compounds) was present only in close relatives and can be thus considered as autapomorphic features. 相似文献
6.
Summary Labeled probes carrying the Anabaena PCC 7120 nitrogenase (nifK and nifD) and nitrogenase reductase (nifH) genes were hybridized to Southern blots of DNA from diverse N2-fixing cyanobacteria in order to test a previous observation of different nif gene organization in nonheterocystous and heterocystous strains. The nif probes showed no significant hybridization to DNA from a unicellular cyanobacterium incapable of N2 fixation. All nonheterocystous cyanobacteria examined (unicellular and filamentous) had a contiguous nifKDH gene cluster whereas all of the heterocystous strains showed separation of nifK from contiguous nifDH genes. These findings suggest that nonheterocystous and heterocystous cyanobacteria have characteristic and fundamentally different nif gene arrangements. The noncontiguous nif gene pattern, as shown with two Het- mutants, is independent of phenotypic expression of heterocyst differentiation and aerobic N2-fixation. Thus nif arrangement could be a useful taxonomic marker to distinguish between phenotypically Het- heterocystous cyanobacteria and phylogenetically unrelated nonheterocystous strains. 相似文献
7.
The phylogeny of unicellular, extremely halotolerant cyanobacteria 总被引:14,自引:0,他引:14
We examined the morphology, physiology, and 16S rRNA gene sequences of three culture collection strains and of ten novel
isolates of unicellular cyanobacteria from hypersaline environments. The strains were morphologically diverse, with average
cell widths ranging from 2.8 to 10.3 μm. There were single-celled, colonial, and baeocyte-forming strains. However, morphological
traits were markedly variable with culture conditions. In contrast, all strains displayed extreme halotolerance (growing close
to optimally at above 12% salinity); all were obligately marine, euryhaline, and moderately thermophilic; and all shared a
suite of chemotaxonomic markers including phycobilins, carotenoids, and mycosporine-like amino acids. 16S rRNA gene sequence
analysis indicated that the strains were related to each other. Sequence similarity analysis placed the strains in a monophyletic
cluster (which we named the Halothece cluster) apart from all cultured or uncultured, not extremely halotolerant cyanobacteria
whose 16S rRNA gene sequences are available in public nucleotide sequence databases. This represents the first case in which
a phylogenetically coherent group of cyanobacteria can be defined on the basis of physiology. The Halothece cluster contained
two subclusters that may be divergent at the generic level, one encompassing 12 strains (spanning 5% 16S rRNA gene sequence
divergence and named the Euhalothece subcluster), and a single deep-branching isolate. Phenotypic characterization of the
isolates, including morphological, physiological, and chemotaxonomic traits, did not distinguish these subclusters and only
weakly suggested the existence of two separate clades, one encompassing strains of small cell size (cell width < 5 m) and
another one encompassing strains of larger cell size.
Received: 1 September 1997 / Accepted: 13 February 1998 相似文献
8.
The organisation of the structural genes for nitrogen fixation (nif K,D and H) in a nonheterocystous, filamentous cyanobacteriumPlectonema boryanum has been examined in comparison with a heterocystous cyanobacterium,Anabaena torulosa. DNA from repressed (fix-) cultures ofA. torulosa showed a discontinuousnif region spread over approximately 18 kb, an arrangement typical of the vegetative cells of heterocystous cyanobacteria. The region contained a contiguousnif DH separated fromnif K. by nearly 11 kb DNA. The intervening 11 kb DNA harboured the genexis A involved in the rearrangement ofnif K,D,H to form a cluster during differentiation of heterocysts. DNA fromPlectonema boryanum had a small, contiguousnif KDH cluster spanning a region of approximately 4 kb. DNA homologous to the 11 kb excison with its residentxis A was not present.Nif hybridisation patterns of restriction digests of the DNA isolated from repressed (fix-) or induced (fix--) cultures ofP. boryanum were completely identical. These results unequivocally demonstrate that in the nonheterocystous cyanobacterium, unlike in the heterocystous strains, no gene rearrangement, either within thenif KDII cluster or in its vicinity, accompanies the expression of nitrogenase activity. 相似文献
9.
An axenic culture of a cyanobacterium (strain HPS) was raised from a field specimen of greenish planktonic floccose mass from a local lake, Ganga Sagar. Intense morphological examination and comparative morphological assessment with the genera Fischerella and Hapalosiphon and all the known strains of the genus Westiellopsis indicated that the strain HPS differed in morphology with the closely related strains in trichome arrangement, size of vegetative cells, heterocytes, monocytes, and number of rows of main filaments. There were also differences in the habitat preference, being aquatic rather than terrestrial or subaerial. Intense ecological characterization of the habitat was performed through measurements of important physicochemical characteristics. 16S rRNA gene-based identification and phylogenetic placement indicated conclusively that the strain HPS was different from the most closely related strain Westiellopsis prolifica SAG 16.93. Phylogenetic inferences drawn in between all the branched heterocytous forms and subsequent 16S-23S ITS analyses and folding of the secondary structures revealed an entirely new form that is unknown till now. Subsequent nifD and rbcL gene-based phylogenetic assessments indicated that strain HPS is phylogenetically different from all the other previously known species of true branching cyanobacteria, along with also pointing toward the huge database inconsistencies in case of true branched cyanobacteria. Assessment of morphological and ecological differences along with comprehensive phylogenetic evaluation indicated that the strain HPS is a new species of the genus Westiellopsis and the name being proposed is Westiellopsis ramosa sp. nov. 相似文献
10.
Luna Viggiano de Alvarenga Stefan Lucius Marcelo Gomes Marçal Vieira Vaz Wagner L. Araújo Martin Hagemann 《Journal of phycology》2020,56(2):496-506
Desmonostoc salinum CCM-UFV059 (Desmonostoc) is a novel cyanobacterial strain of the order Nostocales isolated from a saline-alkaline lake. The acclimation towards salt and desiccation stress of Desmonostoc was compared to the related and well-characterized model strain Nostoc sp. PCC7120 (Nostoc). Salt–stressed cells of Desmonostoc maintained low cellular Na+ concentrations and accumulated high amounts of compatible solutes, mainly sucrose and to a lower extent trehalose. These features permitted Desmonostoc to grow and maintain photosynthesis at 2-fold higher salinities than Nostoc. Moreover, Desmonostoc also induced sucrose over-accumulation under desiccation, which allowed this strain to recover from this stress in contrast to Nostoc. Additional mechanisms such as the presence of highly unsaturated lipids in the membrane and an efficient ion transport system could also explain, at least partially, how Desmonostoc is able to acclimate to high salinities and to resist longer desiccation periods. Collectively, our results provide first insights into the physiological and metabolic adaptations explaining the remarkable high salt and desiccation tolerance, which qualify Desmonostoc as an attractive model for further analysis of stress acclimation among heterocystous N2–fixing cyanobacteria. 相似文献
11.
Analysis of codon usage in genes for nitrogen fixation from phylogenetically diverse diazotrophs 总被引:1,自引:0,他引:1
Summary A cluster analysis based on codon usage in genes for biological nitrogen fixation (nif genes) grouped diazotrophs into three distinct classes: anaerobes, cyanobacteria, and aerobes. In thenif genes ofKlebsiella pneumoniae there was no evidence for selection pressure in favor of highly translatable codons. However, in the nitrogen regulatory operonglnAntrBntrC of enteric bacteria the stoichiometrically high level of glutamine synthetase may be facilitated by the presence of efficiently translatable codons inglnA. Thenif genes of the cyanobacteriumAnabaena showed codon selection in favor of translational efficiency. Computation of codon adaptation indices for expression in heterologous systems indicated that the reading frames most suitable for expression ofnif genes inEscherichia coli, Bacillus subtilis, andSaccharomyces cerevisiae were present in azotobacters, clostridia, and cyanobacteria, respectively. In codon-usage-based cluster analysis, type 3 nitrogenase genes ofAzotobacter vinelandii grouped along with type 1 and type 2 genes. This is in contrast to the nucleotide sequence-based multiple alignment in which type 3 nitrogenase genes ofA. vinelandii have been reported to cluster with entirely unrelated diazotrophs such as methanogens and clostridia. This may be indicative of lateral transfer ofnif genes among widely divergent taxons. The chromosomal- and plasmid-locatednif genes of rhizobia also cluster separately in nucleotide sequence-based analysis but showed similar codon usage. These analyses suggested that the phylogeny ofnif genes drawn on the basis of nucleotide sequence homology was not masked by the taxon-specific pressure on codon usage. 相似文献
12.
An early origin of plastids within the cyanobacterial divergence is suggested by evolutionary trees based on complete 16S rRNA sequences 总被引:10,自引:0,他引:10
Nelissen B; Van de Peer Y; Wilmotte A; De Wachter R 《Molecular biology and evolution》1995,12(6):1166-1173
It is generally accepted that the plastids arose from a cyanobacterial
ancestor, but the exact phylogenetic relationships between cyanobacteria
and plastids are still controversial. Most studies based on partial 16S
rRNA sequences suggested a relatively late origin of plastids within the
cyanobacterial divergence. In order to clarify the exact relationship and
divergence order of cyanobacteria and plastids, we studied their phylogeny
on the basis of nearly complete 16S rRNA gene sequences. The data set
comprised 15 strains of cyanobacteria from different morphological groups,
1 prochlorophyte, and plastids belonging to 8 species of plants and 12
species of diverse algae. This set included three cyanobacterial sequences
determined in this study. This is the most comprehensive set of complete
cyanobacterial and plastidial 16S rRNA sequences used so far. Phylogenetic
trees were constructed using neighbor joining and maximum parsimony, and
the reliability of the tree topologies was tested by different methods. Our
results suggest an early origin of plastids within the cyanobacterial
divergence, preceded only by the divergence of two cyanobacterial genera,
Gloeobacter and Pseudanabaena.
相似文献
13.
Bacem Mnasri Yazid Badri Sabrine Saïdi Philippe de Lajudie Ridha Mhamdi 《Systematic and applied microbiology》2009
Ensifer meliloti (formerly Sinorhizobium meliloti) was first considered as a specific microsymbiont of Medicago, Melilotus and Trigonella. However, strains of E. meliloti were recovered from root nodules of various legume species and their symbiotic status still remains unclear. Here, we further investigate the specificity of these strains. A collection of 47 E. meliloti strains isolated in Tunisia from root nodules of Medicago truncatula, Medicago sativa, Medicago ciliaris, Medicago laciniata, Medicago marina, Medicago scutellata, Phaseolus vulgaris, Cicer arietinum, Argyrolobium uniflorum, Lotus creticus, Lotus roudairei, Ononis natrix, Retama raetam, Genista saharae, Acacia tortilis, Hedysarum carnosum and Hippocrepis bicontorta were examined by REP-PCR fingerprinting, PCR-RFLPs of the 16S-23S rDNA IGS, the nifH gene and nifD-K intergenic spacer, and sequencing of 16S rRNA and nodA genes. Their nodulation range was also assessed by cross-inoculation experiments. No clear correlation was found between chromosomal backgrounds and host plants of origin. The nodulation polyvalence of the species E. meliloti was associated with a high symbiotic heterogeneity. On the basis of PCR-RFLP data from the nifH gene and nifD-K intergenic spacer, E. meliloti strains isolated from non-Medicago legumes harboured distinct genes and possessed wider host ranges. Some strains did not nodulate Medicago species. On the basis of nodA phylogeny, the majority of the Tunisian strains, including strains from Medicago, harboured distinct nodA alleles more related to those found in E. medicae than those found in E. meliloti. However, more work is still needed to characterize this group further. The diversity observed among M. laciniata isolates, which was supported by nodA phylogeny, nifH typing and the efficiency profile on M. ciliaris, indicated that what was thought to be bv. medicaginis is certainly heterogeneous. 相似文献
14.
Ranjan K Sahoo Mohammad W Ansari Madhusmita Pradhan Tushar K Dangar Santanu Mohanty Narendra Tuteja 《Protoplasma》2014,251(4):943-953
Beneficial microorganisms have been considered as an important tool for crop improvement. Native isolates of Azospirillum spp. were obtained from the rhizospheres of different rice fields. Phenotypic, biochemical and molecular characterizations of these isolates led to the identification of six efficient strain of Azospirillum. PCR amplification of the nif genes (nifH, nifD and nifK) and protein profile of Azospirillum strains revealed inter-generic and inter-specific diversity among the strains. In vitro nitrogen fixation performance and the plant growth promotion activities, viz. siderophore, HCN, salicylic acid, IAA, GA, zeatin, ABA, NH3, phosphorus metabolism, ACC deaminase and iron tolerance were found to vary among the Azospirillum strains. The effect of Azospirillum formulations on growth of rice var. Khandagiri under field condition was evaluated, which revealed that the native formulation of Azospirillum of CRRI field (As6) was most effective to elevate endogenous nutrient content, and improved growth and better yield are the result. The 16S rRNA sequence revealed novelty of native Azospirillum lipoferum (As6) (JQ796078) in the NCBI database. 相似文献
15.
The SSU (16S) rRNA gene was used to investigate the phylogeny of the cyanobacterial genus Lyngbya as well as examined for its capacity to discriminate between different marine species of Lyngbya. We show that Lyngbya forms a polyphyletic genus composed of a marine lineage and a halophilic/brackish/freshwater lineage. In addition, we found morphological and genetic evidence that Lyngbya spp. often grow in association with other microorganisms, in particular smaller filamentous cyanobacteria such as Oscillatoria, and propose that these associated microorganisms have led to extensive phylogenetic confusion in identification of Lyngbya spp. At the species level, the phylogenetic diversity obtained from the comparison of 16S rRNA genes exceeded morphological diversity in Lyngbya. However, the expectation that this improved phylogeny would be useful to species and subspecies identification was eliminated by the fact that phylogenetic species did not correlate in any respect with the species obtained from current taxonomic systems. In addition, phylogenetic identification was adversely affected by the presence of multiple gene copies within individual Lyngbya colonies. Analysis of clonal Lyngbya cultures and multiple displacement amplified (MDA) single‐cell genomes revealed that Lyngbya genomes contain two 16S rRNA gene copies, and that these typically are of variable sequence. Furthermore, intragenomic and interspecies 16S rRNA gene heterogeneity was approximately of the same magnitude. Hence, the intragenomic heterogeneity of the 16S rRNA gene overestimates the microdiversity of different strains and does not accurately reflect speciation within cyanobacteria, including the genus Lyngbya. 相似文献
16.
17.
Solène Thomazeau Aude Houdan‐Fourmont Alain Couté Charlotte Duval Arnaud Couloux Florence Rousseau Cécile Bernard 《Journal of phycology》2010,46(3):564-579
To date, phylogenies have been based on known gene sequences accessible at GenBank, and the absence of many cyanobacterial lineages from collections and sequence databases has hampered their classification. Investigating new biotopes to isolate more genera and species is one way to enrich strain collections and subsequently enhance gene sequence databases. A polyphasic approach is another way of improving our understanding of the details of cyanobacterial classification. In this work, we have studied phylogenetic relationships in strains isolated from freshwater bodies in Senegal and Burkina Faso to complement existing morphological and genetic databases. By comparing 16S rDNA sequences of African strains to those of other cyanobacteria lineages, we placed them in the cyanobacterial phylogeny and confirmed their genus membership. We then focused on the Nostocaceae family by concatenated analysis of four genes (16S rDNA, hetR, nifH, and rpoC1 genes) to characterize relationships among Anabaena morphospecies, in particular, Anabaena sphaerica var. tenuis G. S. West. Using a polyphasic approach to the Nostocaceae family, we demonstrate that A. sphaerica var. tenuis is more closely related to Cylindrospermospsis/Raphidiopsis than to other planktonic Anabaena/Aphanizomenon. On the basis of phylogeny and morphological data, we propose that these three significantly different clusters should be assigned to three genera. 相似文献
18.
Aerobic Anoxygenic Photosynthesis in Roseobacter Clade Bacteria from Diverse Marine Habitats
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Martin Allgaier Heike Uphoff Andreas Felske Irene Wagner-Dbler 《Applied microbiology》2003,69(9):5051-5059
The marine Roseobacter clade comprises several genera of marine bacteria related to the uncultured SAR83 cluster, the second most abundant marine picoplankton lineage. Cultivated representatives of this clade are physiologically heterogeneous, and only some have the capability for aerobic anoxygenic photosynthesis, a process of potentially great ecological importance in the world's oceans. In an attempt to correlate phylogeny with ecology, we investigated the diversity of Roseobacter clade strains from various marine habitats (water samples, biofilms, laminariae, diatoms, and dinoflagellate cultures) by using the 16S rRNA gene as a phylogenetic marker gene. The potential for aerobic anoxygenic photosynthesis was determined on the genetic level by PCR amplification and sequencing of the pufLM genes of the bacterial photosynthesis reaction center and on the physiological level by detection of bacteriochlorophyll (Bchl) a. A collection of ca. 1,000 marine isolates was screened for members of the marine Roseobacter clade by 16S rRNA gene-directed multiplex PCR and sequencing. The 42 Roseobacter clade isolates found tended to form habitat-specific subclusters. The pufLM genes were detected in two groups of strains from dinoflagellate cultures but in none of the other Roseobacter clade isolates. Strains within the first group (the DFL-12 cluster) also synthesized Bchl a. Strains within the second group (the DFL-35 cluster) formed a new species of Roseovarius and did not produce Bchl a under the conditions investigated here, thus demonstrating the importance of genetic methods for screening of cultivation-dependent metabolic traits. The pufL genes of the dinoflagellate isolates were phylogenetically closely related to pufL genes from Betaproteobacteria, confirming similar previous observations which have been interpreted as indications of gene transfer events. 相似文献
19.
The 23S rRNA gene was evaluated as target for the development of Sybr Green-based quantitative PCR (qPCR) for the analysis of nitrogen-fixing members of the genus Frankia or subgroups of these in soil. A qPCR with a primer combination targeting all nitrogen-fixing frankiae (clusters 1, 2 and 3) resulted in numbers similar to those obtained with a previously developed qPCR using nifH gene sequences, both with respect to introduced and indigenous Frankia populations. Primer combinations more specifically targeting three subgroups of the Alnus host infection group (cluster 1) or members of the Elaeagnus host infection group (cluster 3) were specific for introduced strains of the target group, with numbers corresponding to those obtained by quantification of nitrogen-fixing frankiae with both the 23S rRNA and nifH genes as target. Method verification on indigenous Frankia populations in soils, i.e. in depth profiles from four sites at an Alnus glutinosa stand, revealed declining numbers in the depth profiles, with similar abundance of all nitrogen-fixing frankiae independent of 23S rRNA or nifH gene targets, and corresponding numbers of one group of frankiae of the Alnus host infection only, with no detections of frankiae representing the Elaeagnus, Casuarina, or a second subgroup of the Alnus host infection groups. 相似文献
20.
Yohei Kurio Yosuke Koike Yu Kanesaki Satoru Watanabe Shigeki Ehira 《Molecular microbiology》2020,114(4):553-562