Motility and flagellum synthesis in Halobacillus halophilus are chloride dependent.
(1/51)
The motility of Halobacillus halophilus as observed on swarm agar plates was strictly dependent on the chloride concentration. Cl(-) was apparently not used as the coupling ion for flagellar rotation. Cells grown in the absence of chloride were devoid of flagella, but flagellation was restored upon the addition of chloride. These experiments indicate that chloride is involved in synthesis of flagella in H. halophilus. (+info)
Phylogenetic position of the North American isolate of Pasteuria that parasitizes the soybean cyst nematode, Heterodera glycines, as inferred from 16S rDNA sequence analysis.
(2/51)
A 1341 bp sequence of the 16S rDNA of an undescribed species of Pasteuria that parasitizes the soybean cyst nematode, Heterodera glycines, was determined and then compared with a homologous sequence of Pasteuria ramosa, a parasite of cladoceran water fleas of the family Daphnidae. The two Pasteuria sequences, which diverged from each other by a dissimilarity index of 7%, also were compared with the 16S rDNA sequences of 30 other bacterial species to determine the phylogenetic position of the genus Pasteuria among the Gram-positive eubacteria. Phylogenetic analyses using maximum-likelihood, maximum-parsimony and neighbour-joining methods showed that the Heterodera glycines-infecting Pasteuria and its sister species, P. ramosa, form a distinct line of descent within the Alicyclobacillus group of the Bacillaceae. These results are consistent with the view that the genus Pasteuria is a deeply rooted member of the Clostridium-Bacillus-Streptococcus branch of the Gram-positive eubacteria, neither related to the actinomycetes nor closely related to true endospore-forming bacteria. (+info)
Thermacetogenium phaeum gen. nov., sp. nov., a strictly anaerobic, thermophilic, syntrophic acetate-oxidizing bacterium.
(3/51)
A novel anaerobic, thermophilic, syntrophic acetate-oxidizing bacterium, strain PB(T), was isolated from a thermophilic (55 degrees C) anaerobic methanogenic reactor which had been treating kraft-pulp waste water. The bacterium oxidized acetate in co-culture with a thermophilic hydrogenotrophic methanogen. Strain PB(T), a gram-positive, spore-forming, rod-shaped bacterium grew optimally at 58 degrees C and pH 6.8. The bacterium grew acetogenically on several alcohols, methoxylated aromatics, pyruvate, glycine, cysteine, formate and hydrogen/CO2. Strain PB(T) also oxidized acetate with reduction of sulfate or thiosulfate as the electron acceptor. The bacterium contained MK-7 as the major quinone. The G+C content of the DNA was 53.5 mol%. Comparative 16S rDNA analysis indicated that strain PB(T) belongs to the Bacillus-Clostridium subphylum. However, it was distant from any known genera or micro-organism. The closest known relative was Thermoterrabacterium ferrireducens with 87.4% similarity. The name Thermacetogenium phaeum gen. nov., sp. nov. is proposed. The type strain is strain PBT (= DSM 12270T). (+info)
Paenibacillus borealis sp. nov., a nitrogen-fixing species isolated from spruce forest humus in Finland.
(4/51)
Seven spore-forming, nitrogen-fixing bacterial isolates from spruce forest humus in Finland were studied using the polyphasic approach. PCR amplification of 16S rRNA gene fragment with specific primers showed that the isolates were members of Paenibacillus. Levels of 16S rDNA similarity between the isolates were 97.3-100.0% and those between the isolates and other Paenibacillus species were 90.3-96.5%. The highest similarities were observed with Paenibacillus azotofixans and Paenibacillus durus. Ribotyping with EcoRI and PvuII restriction showed a high diversity in the Paenibacillus species and distinguished the isolates from these closely related species. The main whole-cell fatty acids were anteiso-C15:0 (33-48%), straight-chain C14:0 (7-21%) and C16:0 (9-20%), and iso-C15:0 (6-15%). Electron microscopy revealed a unique striped morphology of the spore surfaces. Based on phylogenetic inference and phenotypic and chemotaxonomic characteristics, these isolates are proposed as a new species, Paenibacillus borealis sp. nov., the type strain of which is KK19T (= DSM 13188T = CCUG 43137T). (+info)
Timing, localization, and persistence of colonization by segmented filamentous bacteria in the neonatal mouse gut depend on immune status of mothers and pups.
(5/51)
As a member of the indigenous gut mucosal microbiota, segmented filamentous bacteria (SFB) colonize the guts of a variety of vertebrates and invertebrates. They are potent microbial stimuli of the gut mucosal immune system. In the small intestines of mice and rats, it has been observed that SFB are absent during the suckling period and appear in high numbers shortly after weaning, then quickly retreat to the cecum and large intestine. In this study, we explored whether this microecological phenomenon resulted from the interaction between SFB and the passively acquired maternal mucosal immunity and/or the actively acquired mucosal immunity. We set up a mouse model by reciprocal crossings and backcrossings of SFB-monoassociated, formerly germ-free, immunocompetent (+/+) BALB/c mice and immunodeficient (scid/scid) mice to produce pups which are either immunocompetent (scid/+) or immunodeficient (scid/scid) and are born either to immunocompetent (scid/+) mothers or to immunodeficient (scid/scid) mothers. We monitored the number of SFB on the mucosa of the small intestine in the four different groups of mice after birth, as well as the level of passively acquired antibodies, the active gut mucosal immune responses, and immunoglobulin A (IgA) coating of SFB in the gut. The results showed that, irrespective of whether the pups were scid/scid or scid/+, SFB could be found earlier on the mucosa of the small intestine in pups born to scid/scid mothers, appearing from day 13 and rapidly reaching a climax around weaning time on day 28, compared to the significantly delayed colonization in the pups of scid/+ mothers, starting from day 16 and peaking around days 28 to 32. After the climax, SFB quickly declined to very low levels in the small intestines of scid/+ pups of either scid/scid mothers or scid/+ mothers, whereas they remained at high levels in scid/scid pups at least until day 70, the last observation time in this study. The dynamic changes in SFB colonization of the small intestines of the different groups of pups may be related to the dynamic changes in the levels of SFB coated with secretory IgA (sIgA), which resulted from the significantly different levels of sIgA obtained from the mothers' milk during the suckling period and, later, of self-produced sIgA in the small intestine. Nevertheless, it is evident that the timing, localization, and persistence of colonization of the neonatal gut by SFB depends on the immune status of both mothers and pups. (+info)
Postdivisional synthesis of the Sporosarcina ureae DNA translocase SpoIIIE either in the mother cell or in the prespore enables Bacillus subtilis to translocate DNA from the mother cell to the prespore.
(6/51)
The differentiation of vegetative cells of Bacillus subtilis into spores involves asymmetric cell division, which precedes complete chromosome partitioning. The DNA translocase SpoIIIE is required to translocate the origin distal 70% of the chromosome from the larger mother cell into the smaller prespore, the two cells that result from the division. We have tested the effect of altering the time and location of SpoIIIE synthesis on spore formation. We have expressed the spoIIIE homologue from Sporosarcina ureae in B. subtilis under the control of different promoters. Expression from either a weak mother cell-specific (sigma(E)) promoter or a weak prespore-specific (sigma(F)) promoter partly complemented the sporulation defect of a spoIIIE36 mutant; however, expression from a strong prespore-specific (sigma(F)) promoter did not. DNA translocation from the mother cell to the prespore was assayed using spoIIQ-lacZ inserted at thrC; transcription of spoIIQ occurs only in the prespore. Translocation of thrC::spoIIQ-lacZ into the prespore occurred efficiently when spoIIIE(Su) was expressed from the weak sigma(E)- or sigma(F)-controlled promoters but not when it was expressed from the strong sigma(F)-controlled promoter. It is speculated that the mechanism directing SpoIIIE insertion into the septum in the correct orientation may accommodate slow postseptational, prespore-specific SpoIIIE synthesis but may be swamped by strong prespore-specific synthesis. (+info)
Detection and characterization of Pasteuria 16S rRNA gene sequences from nematodes and soils.
(7/51)
Various bacterial species in the genus Pasteuria have great potential as biocontrol agents against plant-parasitic nematodes, although study of this important genus is hampered by the current inability to cultivate Pasteuria species outside their host. To aid in the study of this genus, an extensive 16S rRNA gene sequence phylogeny was constructed and this information was used to develop cultivation-independent methods for detection of Pasteuria in soils and nematodes. Thirty new clones of Pasteuria 16S rRNA genes were obtained directly from nematodes and soil samples. These were sequenced and used to construct an extensive phylogeny of this genus. These sequences were divided into two deeply branching clades within the low-G + C, Gram-positive division; some sequences appear to represent novel species within the genus Pasteuria. In addition, a surprising degree of 16S rRNA gene sequence diversity was observed within what had previously been designated a single strain of Pasteuria penetrans (P-20). PCR primers specific to Pasteuria 16S rRNA for detection of Pasteuria in soils were also designed and evaluated. Detection limits for soil DNA were 100-10,000 Pasteuria endospores (g soil)(-1). (+info)
'Candidatus pasteuria usgae' sp. nov., an obligate endoparasite of the phytoparasitic nematode Belonolaimus longicaudatus.
(8/51)
Taxonomically relevant characteristics of a fastidiously Gram-positive, obligately endoparasitic prokaryote (strain S-1) that uses the phytoparasitic sting nematode Belonolaimus longicaudatus as its host are reviewed. 16S rDNA sequence similarity (> or = 93%) confirms its congeneric ranking with other Pasteuria species and strains from nematodes and cladocerans and corroborates morphological, morphometric and host range evidence suggesting a novel taxon. The 16S rDNA sequence of strain S-1 has greatest similarity (96%) to the 16S rDNA sequences of both Pasteuria penetrans from root-knot nematodes (Meloidogyne species) and the recently reported strain of Pasteuria isolated from the soybean cyst nematode Heterodera glycines. Because the obligately endoparasitic nature of prokaryotes in the genus Pasteuria prevents isolation of definitive type strains, strain S-1 is proposed as 'Candidatus Pasteuria usgae' sp. nov. (+info)