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1.
Summary 1. From the proventriculus ofTriatoma infestans aPseudomonas species could always be obtained in pure culture by simple means.2. The bacteria isolated out of the ventriculus of various bugs appeared to agree, not only morphologically but also biochemically and agglutinatorically.3. Further evidence for the identity of the intracellular and the lumen form of this bacterium could be furnished by serological means.4. The assumption expressed byWigglesworth that the infection of the young bug would occur already in the egg and his view on the means by which the egg is infected are very much open to question.5. It does not appear probable that the bacterium, isolated byWigglesworth fromRhodnus prolixus is identical with the proventriculus bacterium ofTriatoma infestans.6. The intracellular bacteria set free into the lumen of the proventriculus have in virtue of their haemodigestive capacity, probably a function in the digestion of the blood sucked by the bug.  相似文献   

2.
A small rod, capable of forming crater-like plaques on lawns of Vibrio parahaemolyticus, was isolated from a marine environment. The isolate was a gram-negative straight rod with round ends and was small in size, equal to that of halophilic Bdellovibrio strain 5501. The isolate appeared to have close taxonomic relationships to Cytophaga, since this bacterium moved slowly in a gliding manner on a solid agar surface, hydrolyzed agar and starch, contained yellow pigment and was halophilic. The isolate was able to grow not only under host-dependent but also under host-independent conditions when low nutrient media were used for cultivation, and its bacteriolytic mode was different from that of Bdellovibrio, an endoparasite. The isolate was halophilic and required Mg++ and Ca++ in addition to 3% saline for growth. The isolate showed a broad host range when tested for plaque-forming activity on gram-negative bacteria but not on the gram-positive bacteria tested so far.  相似文献   

3.
A new species of halophilic anoxygenic purple bacteria of the genus Rhodospirillum is described. The new organism, isolated from water/sediment of the Dead Sea, was vibrio-shaped and an obligate halophile. Growth was best at 12% NaCl, with only weak growth occurring at 6% or 21% NaCl. Growth occurred at Mg2+ concentrations up to 1 M but optimal growth was obtained at 0.05–0.1 M Mg2+. Bromide was well tolerated as an alternative anion to chloride. The new organism is an obligate phototroph, growing photoheterotrophically in media containing yeast extract and acetate or a few other organic compounds. Growth of the Dead Sea Rhodospirillum species under optimal culture conditions was slow (minimum td 20 h). Cells contained bacteriochlorophyll a and carotenoids of the spirilloxanthin series and mass cultures were pink in color. Absorption spectra revealed the presence of a B875 (light-harvesting I) but no B800/B850 (light-harvesting II) photopigment complex. The new organism shares a number of properties with the previously described halophilic phototrophic bacterium Rhodospirillum salinarum and was shown to be related to this phototroph by 16S rRNA sequencing. However, because of its salinity requirements, photosynthetic properties, and isolation from the Dead Sea, the new phototroph is proposed as a new species of the genus Rhodospirillum, R. sodomense.  相似文献   

4.
5.
Summary Tissue cultures of sugarcane support abundant growth ofAzospirillum brasilense (SP 7). Visible after 1–2 weeks as a white or pink slime, this growth reaches 2×108 bacteria/mm2 on the surface of callus. Growth of the bacterium is strictly extracellular in viable callus, and instances of intracellular growth result from rupture of the cell wall during senescence of callus tissue. A significant proportion of the bacterial population on callus is pleomorphic. Varying the nitrogen source in the nutrient medium caused no obvious effect on callus cell structure. The presence of the bacterium caused structural alterations in callus cells which did not inhibit overall growth of the bacterium. Growth of callus as tight groups of cells lacking intercellular spaces may be important for the establishment of a long-term association withAzospirillum. The interface of bacteria and live callus tissue is at the surface of tight cell groups. Browning of the surface cell layers of these groups in the presence ofAzospirillum is not of the rapid nature known for hypersensitivity reactions. Rather, this production of phenolics appears to be due to the accumulation of extracellular bacterial metabolites. The ultrastructure of this and other callus reactions is described. As evidenced by organogenesis, the associated cultures have remained viable for at least 18–20 months.Florida Agricultural Experiment Station Journal Series No. 1695.  相似文献   

6.
Extensive diversity in features of aromatic amino acid biosynthesis and regulation has become recognized in eubacteria, but almost nothing is known about the extent to which such diversity exists within the archaebacteria. Methanohalophilus mahii, a methylotrophic halophilic methanogen, was found to synthesize l-phenylalanine and l-tyrosine via phenylpyruvate and 4-hydroxyphenylpyruvate, respectively. Enzymes capable of using l-arogenate as substrate were not found. Prephenate dehydrogenase was highly sensitive to feedback inhibition by l-tyrosine and could utilize either NADP+ (preferred) or NAD+ as cosubstrate. Tyrosine-pathway dehydrogenases having the combination of narrow specificity for a cyclohexadienyl substrate but broad specificity for pyridine nucleotide cofactor have not been described before. The chorismate mutase enzyme found is a member of a class which is insensitive to allosteric control. The most noteworthy character state was prephenate dehydratase which proved to be subject to multimetabolite control by feedback inhibitor (l-phenylalanine) and allosteric activators (l-tyrosine, l-tryptophan, l-leucine, l-methionine and l-isoleucine). This interlock type of prephenate dehydratase, also known to be broadly distributed among the gram-positive lineage of the eubacteria, was previously shown to exist in the extreme halophile, Halobacterium vallismortis. The results are consistent with the conclusion based upon 16S rRNA analyses that Methanomicrobiales and the extreme halophiles cluster together.Abbreviation DAHP 3-deoxy-d-arabino-heptulosonate-7-phosphate  相似文献   

7.
Root-associating bacteria of the nipa palm (Nypa fruticans), preferring brackish-water affected mud in Sarawak, Malaysia, were investigated. In a comparison of rhizobacterial microbiota between the nipa and the sago (Metroxylon sagu) palm, it was found that the nipa palm possessed a group of Burkholderia vietnamiensis as its main active nitrogen-fixing endophytic bacterium. Acetylene reduction by the various isolates of B. vietnamiensis was constant (44 to 68 nmol h?1 in ethylene production rate) in soft gel medium containing 0.2% sucrose as sole carbon source, and the bacterium also showed motility and biofilm-forming capacity. This is the first report of endophytic nitrogen-fixing bacteria from nipa palm.  相似文献   

8.
Abstract

Several dissimilatory metal-reducing bacteria and a halophilic bacterium are able to induce manganese carbonate (rhodochrosite) precipitation. In this study, it was revealed that Ensifer adhaerens JCM 21105T, Microbacterium testaceum JCM 1353T, Pseudomonas protegens DSM 19095T, and Rheinheimera texasensis DSM 17496T, which are calcite-forming bacteria, were able to aerobically induce the precipitation of manganese carbonate crystals on an agar medium. In the case of all four strains, the principal morphology of the precipitated manganese carbonate crystals was that of micro-sized spheres, when they were aerobically cultivated over the entire surface of the agar medium at 28?°C for 7?days.  相似文献   

9.
Summary By means of partial illumination with small spots of monochromatic light, polarized obliquely to the cell axis, we could demonstrate that the phytochrome molecules inMougeotia are oriented in a spiral pattern around the cell surface. The lines of this spiral form an angle of about 45o with the cell axis. The degree of exactness of this orientation has been discussed.

Mit 7 Textabbildungen

Herrn Professor Dr.E. Heitz zum 70. Geburtstag.  相似文献   

10.
Recent metagenomic studies on saltern ponds with intermediate salinities have determined that their microbial communities are dominated by both Euryarchaeota and halophilic bacteria, with a gammaproteobacterium closely related to the genera Alkalilimnicola and Arhodomonas being one of the most predominant microorganisms, making up to 15% of the total prokaryotic population. Here we used several strategies and culture media in order to isolate this organism in pure culture. We report the isolation and taxonomic characterization of this new, never before cultured microorganism, designated M19-40T, isolated from a saltern located in Isla Cristina, Spain, using a medium with a mixture of 15% salts, yeast extract, and pyruvic acid as the carbon source. Morphologically small curved cells (young cultures) with a tendency to form long spiral cells in older cultures were observed in pure cultures. The organism is a Gram-negative, nonmotile bacterium that is strictly aerobic, non-endospore forming, heterotrophic, and moderately halophilic, and it is able to grow at 10 to 25% (wt/vol) NaCl, with optimal growth occurring at 15% (wt/vol) NaCl. Phylogenetic analysis based on 16S rRNA gene sequence comparison showed that strain M19-40T has a low similarity with other previously described bacteria and shows the closest phylogenetic similarity with species of the genera Alkalilimnicola (94.9 to 94.5%), Alkalispirillum (94.3%), and Arhodomonas (93.9%) within the family Ectothiorhodospiraceae. The phenotypic, genotypic, and chemotaxonomic features of this new bacterium showed that it constitutes a new genus and species, for which the name Spiribacter salinus gen. nov., sp. nov., is proposed, with strain M19-40T (= CECT 8282T = IBRC-M 10768T = LMG 27464T) being the type strain.  相似文献   

11.
The generic term “quorum sensing” has been adopted to describe the bacterial cell-to-cell communication mechanism which coordinates gene expression when the population has reached a high cell density. Quorum sensing depends on the synthesis of small molecules that diffuse in and out of bacterial cells. There are few reports about this mechanism in Archaea. We report the isolation and chemical characterization of small molecules belonging to class of diketopiperazines (DKPs) in Haloterrigena hispanica, an extremely halophilic archaeon. One of the DKPs isolated, the compound cyclo-(l-prolyl–l-valine) activated N-acyl homoserine lactone (AHL) bioreporters, indicating that Archaea may have the ability to interact with AHL-producing bacteria within mixed communities.  相似文献   

12.
The genes involved in biosynthesis of the major compatible solute ectoine (1,4,5,6-tetrahydro-2-methylpyrimidine carboxylic acid) in halotolerant obligate methanotroph “Methylomicrobium alcaliphilum 20Z” were studied. The complete nucleotide sequences of the structural genes encoding l-aspartokinase (Ask), l-2,4-diaminobutyric acid transaminase (EctB), l-2,4-diaminobutyric acid acetyltransferase (EctA), and l-ectoine synthase (EctC) were defined and shown to be transcribed as a single operon ectABCask. Phylogenetic analysis revealed high sequence identities (34–63%) of the Ect proteins to those from halophilic heterotrophs with the highest amino acid identities being to Vibrio cholerae enzymes. The chromosomal DNA fragment from “M. alcaliphilum 20Z” containing ectABC genes and putative promoter region was expressed in Escherichia coli. Recombinant cells could grow in the presence of 4% NaCl and synthesize ectoine. The data obtained suggested that despite the ectoine biosynthesis pathway being evolutionary well conserved with respect to the genes and enzymes involved, some differences in their organization and regulation could occur in various halophilic bacteria.Dedicated to the 70th birthday of Professor Gerhard Gottschalk who inspired our studies on methylotrophic haloalkaliphiles.  相似文献   

13.
Abstract A simulation model was constructed in which two model bacteria competed with each other in a closed system to which periodic substrate additions were made. One bacterium responded to starvation by entering into a dormant state characterized by a decreased death rate; the other bacterium did not make this transition. The periodicity of substrate addition was varied, and the magnitude of selection for one bacterial type was calculated. For model parameters typical of those measured in Escherichia coli, positive selection for the bacterium capable of the starvation response only occurred if the time interval of substrate addition exceeded 54 times the minimum doubling time of the bacterium. The magnitude of the selection coefficient was most sensitive to two model parameters: the time constant for conversion of dormant cells back to actively growing ones, and the magnitude of the death rate of cells which did not undergo the starvation response. Received: 30 April 1999; Accepted: 3 August 1999; Online Publication: 15 February 2000  相似文献   

14.
Pseudomonas aeruginosa may cause serious infections in most human tissues/organs. Its adherence to them is mediated by a battery of adhesins including the PA-I and PA-II lectins, which are produced in this bacterium in high quantities. PA-I binds to thed-galactose of the erythrocyte glycosphingolipids exhibiting highest affinities for B and Pk (followed by P1) antigens, while PA-II preferentially binds to thel-fucose of H, A and B antigens. IntactP. aeruginosa cells also exhibit a clear Pk and P1 over p preference. Such affinities for the most common human ABH and P system antigens may underlie the widespread tissue infectivity and pathogenicity of this bacterium.  相似文献   

15.
Anti-glutamine synthetase serum was raised in rabbits by injecting purified glutamine synthetase (GS) of the phototrophic bacterium Rhodopseudomonas capsulata E1F1. The antibodies were purified to monospecificity by immunoaffinity chromatography in GS-sepharose gel. These anti-GS antibodies were used to measure the antigen levels in crude extracts from bacteria, grown phototrophically with dinitrogen, nitrate, nitrite, ammonia, glutamate, glutamine or alanine as nitrogen sources. The amount of GS detected by rocket immunoelectrophoresis was proportional to Mn2+-dependent transferase activity measured in the crude extracts. Addition of GS inhibitor l-methionine-d,l-sulfoximine (MSX) to the actively growing cells promoted increased antigen levels, that were not found in the presence of glutamine or chloramphenicol. The ammonia-induced decrease in GS relative levels was reverted by MSX. GS levels remained constant when phototrophically growing cells were kept in the dark.Abbreviations GS glutamine synthetase - MOPS 2-(N-morpholine) propane sulfonate - MSX l-methionine-d,l-sulfoximine  相似文献   

16.
Cell-free extracts of the green sulfur bacterium Chlorobium limicola forma thiosulfatophilum strains 1C and L have been shown to cleave citrate with the formation of oxaloacetate and acetyl-CoA. This capacity was found in autotrophically grown cells as well as in the cells grown on media with acetate or L-glutamate. Citrate lyase activity in cell-free extracts is only measurable in the presence of citrate, adenosine-5-triphosphate, coenzyme A and Mg2+ or Mn2+. It is concluded on the basis of the obtained data that C. limicola f. thiosulfatophilum contains adenosine-5-triphosphate-linked citrate lyase (E.C.4.1.3.8). In contrast to green bacteria in the purple bacteria Ectothiorhodospira shaposhnikovii, Rhodospirillum rubrum and Thiocapsa roseopersicina citrate lyase activity was not found.  相似文献   

17.
18.
Summary Actively motile bacteria became non-motile when plasmolyzed and they regained their motile function when deplasmolyzed. Many of the species observed spontaneously reverted to motile forms if allowed to remain sufficiently long in the plasmolyzing medium. The time required for resumption of motility could be decreased markedly by addition of tryptone, or dl-alanyl-dl-serine, or l-alanine to the medium. Motility resumption occurred when the bacteria stained in a manner similar to that of non-plasmolyzed forms, that is, evenly rather than bipolarly, thus suggesting that the displacement of the membrane influenced motile function.The resumption of motility by plasmolyzed bacteria may serve as a simple screening test for compounds having permeability change effects on the bacterial cytoplasmic membrane as their mode of action.  相似文献   

19.
Summary Comparative cataloging of the 16S rRNA ofHalobacterium halobium indicates that the organism did not arise, as a halophilic adaptation, from some typical bacterium. Rather,H. halobium is a member of the Archaebacteria, an ancient group of organisms that are no more related to typical bacteria than they are to eucaryotes.  相似文献   

20.
A comparative electron microscope study at magnifications ranging from about 80,000 up to 800,000 x was carried out in nine species of insects (Gryllus argentinus, Myogryllus verticalis, undetermined species of Gryllus; Blaptica dubia, Periplaneta americana, Blattella germanica; Laplatacris dispar, Aleua lineata and Omexechae servillei). Particular attention was paid: a) to the elementary components of the s. complexes and b) to the structure of their medial ribbon. - a) In all the species examined the basic element found is a curled filament some 15–20 Å thick. Filaments of this kind integrate: the 100 Å fibrils of the chromosome body, the compacts layers of the s. complexes (lateral arms) and the slender planes of the pairing space. The filaments are similar to those described in metaphase chromosomes and their kinetochores (Wettstein and Sotelo, 1965). A difference in density between the filaments of the lateral arms and those of the medial planes is sometimes noticed. - b) Three structural patterns were found in the pairing space. In crickets, the medial ribbon is composed of three parallel, longitudinal planes of filaments, interconnected and connected with the lateral arms by means of bridges. The latter are constituted by fibrils or by single filaments. In cockroaches only two longitudinal planes were found. The distribution of components in these planes follows a plan similar to the one found in crickets. In the electron-micrographs the medial component of both groups of Insecta appears as composed of three (crickets) or two (cockroaches) lines in the longitudinal frontal views, and ladder-like striated in lateral views. The latter striae correspond to filaments or groups of filaments running in antero-posterior direction. - The pattern of structure of grasshoppers differs completely from those mentioned above. Bridging between the homologues is made of regularly spaced transversal planes of filaments. No longitudinal array was observed.This investigation was supported by United States Public Health Service Research Grant GM 08337 from the Research Grants Branch, Division of Medical Sciences, and partly by Grant RF 61034 from The Rockefeller Foundation.  相似文献   

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