Adaptation to extreme environments: macromolecular dynamics in bacteria compared in vivo by neutron scattering.
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Mean macromolecular dynamics was quantified in vivo by neutron scattering in psychrophile, mesophile, thermophile and hyperthermophile bacteria. Root mean square atomic fluctuation amplitudes determining macromolecular flexibility were found to be similar for each organism at its physiological temperature ( approximately 1 A in the 0.1 ns timescale). Effective force constants determining the mean macromolecular resilience were found to increase with physiological temperature from 0.2 N/m for the psychrophiles, which grow at 4 degrees C, to 0.6 N/m for the hyperthermophiles (85 degrees C), indicating that the increase in stabilization free energy is dominated by enthalpic rather than entropic terms. Larger resilience allows macromolecular stability at high temperatures, while maintaining flexibility within acceptable limits for biological activity. (+info)
Impact of violacein-producing bacteria on survival and feeding of bacterivorous nanoflagellates.
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We studied the role of bacterial secondary metabolites in the context of grazing protection against protozoans. A model system was used to examine the impact of violacein-producing bacteria on feeding rates, growth, and survival of three common bacterivorous nanoflagellates. Freshwater isolates of Janthinobacterium lividum and Chromobacterium violaceum produced the purple pigment violacein and exhibited acute toxicity to the nanoflagellates tested. High-resolution video microscopy revealed that these bacteria were ingested by the flagellates at high rates. The uptake of less than three bacteria resulted in rapid flagellate cell death after about 20 min and cell lysis within 1 to 2 h. In selectivity experiments with nontoxic Pseudomonas putida MM1, flagellates did not discriminate against pigmented strains. Purified violacein from cell extracts of C. violaceum showed high toxicity to nanoflagellates. In addition, antiprotozoal activity was found to positively correlate with the violacein content of the bacterial strains. Pigment synthesis in C. violaceum is regulated by an N-acylhomoserine lactone (AHL)-dependent quorum-sensing system. An AHL-deficient, nonpigmented mutant provided high flagellate growth rates, while the addition of the natural C. violaceum AHL could restore toxicity. Moreover, it was shown that the presence of violacein-producing bacteria in an otherwise nontoxic bacterial diet considerably inhibited flagellate population growth. Our results suggest that violacein-producing bacteria possess a highly effective survival mechanism which may exemplify the potential of some bacterial secondary metabolites to undermine protozoan grazing pressure and population dynamics. (+info)
Collimonas fungivorans gen. nov., sp. nov., a chitinolytic soil bacterium with the ability to grow on living fungal hyphae.
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A polyphasic approach was used to describe the phylogenetic position of 22 chitinolytic bacterial isolates that were able to grow at the expense of intact, living hyphae of several soil fungi. These isolates, which were found in slightly acidic dune soils in the Netherlands, were strictly aerobic, Gram-negative rods. Cells grown in liquid cultures were flagellated and possessed pili. A wide range of sugars, alcohols, organic acids and amino acids could be metabolized, whereas several di- and trisaccharides could not be used as substrates. The major cellular fatty acids were C(16 : 0), C(16 : 1)omega7c and C(18 : 1)omega7c. DNA G+C contents were 57-62 mol%. Analysis of nearly full-length 16S rDNA sequences showed that the isolates were related closely to each other (>98.6 % sequence similarity) and could be assigned to the beta-Proteobacteria, family 'Oxalobacteraceae', order 'Burkholderiales'. The most closely related species belonged to the genera Herbaspirillum and Janthinobacterium, exhibiting 95.9-96.7 % (Herbaspirillum species) and 94.3-95.6 % (Janthinobacterium species) 16S rDNA sequence similarity to the isolates. Several physiological and biochemical properties indicated that the isolates could be distinguished clearly from both of these genera. Therefore, it is proposed that the isolates described in this study are representatives of a novel genus, Collimonas gen. nov. Genomic fingerprinting (BOX-PCR), detailed analysis of 16S rDNA patterns and physiological characterization (Biolog) of the isolates revealed the existence of four subclusters. The name Collimonas fungivorans gen. nov., sp. nov. has been given to one subcluster (four isolates) that appears to be in the centre of the novel genus; isolates in the other subclusters have been tentatively named Collimonas sp. The type strain of Collimonas fungivorans gen. nov., sp. nov. is Ter6(T) (=NCCB 100033(T)=LMG 21973(T)). (+info)
Duganella violaceinigra sp. nov., a novel mesophilic bacterium isolated from forest soil.
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A mesophilic bacterium, designated strain YIM 31327T, was isolated from a forest soil sample collected from Yunnan Province, China, and was then investigated using a polyphasic approach. The strain grew optimally at 28-30 degrees C and pH 7.2. The cells were Gram-negative, short, rod-shaped, motile and non-spore-forming with flagella. The major ubiquinone was Q-8 and the cellular fatty acids were C(16 : 0) and C(12 : 0). The DNA G + C content of strain YIM 31327T was 62.8 mol%. Phylogenetic analysis revealed that strain YIM 31327T was a member of the beta-Proteobacteria, being most closely related to Duganella zoogloeoides, with which it exhibited less than 96 % 16S rRNA gene sequence similarity. On the basis of the phenotypic and genotypic differences between strain YIM 31327T and D. zoogloeoides, a novel species, Duganella violaceinigra sp. nov., is proposed, with YIM 31327T (= CIP 108077T = KCTC 12193T) as the type strain. (+info)
Naxibacter alkalitolerans gen. nov., sp. nov., a novel member of the family 'Oxalobacteraceae' isolated from China.
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A taxonomic study was performed on strain YIM 31775(T), which was isolated from a soil sample collected from Yunnan Province, China. The isolate was chemo-organotrophic, aerobic and Gram-negative. Cells were short rods and motile, with one or more polar flagella. Growth temperature and pH ranged from 4 to 55 degrees C and 6.5 to 12.0, respectively; the optimum growth temperature and pH were 28-37 degrees C and 7.0-9.0, respectively. Q-8 was the predominant respiratory lipoquinone. The major fatty acids were C(16 : 1)omega7c (42.4 %) and C(16 : 0) (28.1 %). The DNA G + C content was 62.4 +/ -0.3 mol%. Phylogenetic analysis based on the 16S rRNA gene sequence indicated that strain YIM 31775(T) should be placed within the family 'Oxalobacteraceae', in which it formed a distinct lineage. Based on the high 16S rRNA gene sequence divergence and phenotypic characteristics, it is proposed that strain YIM 31775(T) should be classified as representing a novel member of the family 'Oxalobacteraceae', for which the name Naxibacter alkalitolerans gen. nov., sp. nov. is proposed. The type strain is YIM 31775(T) (= CCTCC AA 204003(T) = KCTC 12194(T)). (+info)
Massilia dura sp. nov., Massilia albidiflava sp. nov., Massilia plicata sp. nov. and Massilia lutea sp. nov., isolated from soils in China.
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Four Gram-negative, motile, rod-shaped bacterial strains were isolated from soil samples collected from south-east China. A taxonomic study including phylogenetic analysis based on 16S rRNA gene sequences and phenotypic characteristics was performed. DNA G+C contents of the four strains were 63-66 mol%. Their predominant ubiquinone was Q-8. The fatty acid profiles contained C16:1omega7c (36.9-54.7%) and C16:0 (22.8-25.5%) as the major components. Based on their phenotypic characteristics, phylogenetic position as determined by 16S rRNA gene sequence analysis and DNA-DNA hybridization results, the four isolates are considered to represent four novel species of the genus Massilia, for which the names Massilia dura sp. nov. (type strain 16T=CCTCC AB 204070T=KCTC 12342T), Massilia albidiflava sp. nov. (type strain 45T=CCTCC AB 204071T=KCTC 12343T), Massilia plicata sp. nov. (type strain 76T=CCTCC AB 204072T=KCTC 12344T) and Massilia lutea sp. nov. (type strain 101T=CCTCC AB 204073T=KCTC 12345T) are proposed. (+info)
Herminiimonas arsenicoxydans sp. nov., a metalloresistant bacterium.
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An arsenite-oxidizing bacterium, designated strain ULPAs1(T), was isolated from industrial sludge heavily contaminated with arsenic. Cells of this isolate were Gram-negative, curved rods, motile by means of a polar flagellum. The strain was positive for oxidase and catalase activities, was able to reduce nitrate to nitrite, used acetate, lactate and peptone as organic carbon sources under aerobic conditions and was able to oxidize arsenite (As[III]) to arsenate (As[V]). 16S rRNA gene sequence analysis and the absence of dodecanoic fatty acids suggested that this strain represents a member of the genus Herminiimonas of the family Oxalobacteraceae, order Burkholderiales in the Betaproteobacteria. Genomic DNA-DNA hybridization between strain ULPAs1(T) and Herminiimonas fonticola S-94(T) and between strain ULPAs1(T) and Herminiimonas aquatilis CCUG 36956(T) revealed levels of relatedness of <10 %, well below the recommended 70 % species cut-off value. Thus, strain ULPAs1(T) (=CCM 7303(T)=DSM 17148(T)=LMG 22961(T)) is the type strain of a novel species of Herminiimonas, for which the name Herminiimonas arsenicoxydans sp. nov. is proposed. (+info)
Massilia aurea sp. nov., isolated from drinking water.
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A Gram-negative, motile, rod-shaped organism, strain AP13(T), able to produce yellow-pigmented colonies, was isolated from the drinking water distribution system of Seville (Spain) and was characterized by using a polyphasic taxonomic approach. In 16S rRNA gene sequence comparisons, strain AP13(T) exhibited 96.9-95.6 % similarity with respect to the five recognized species of the genus Massilia. The DNA G+C content of strain AP13(T) was 66.0 mol%, a value that supports the affiliation of strain AP13(T) to the genus Massilia. DNA-DNA hybridization data and phenotypic properties confirmed that strain AP13(T) represents a novel species of the genus Massilia, for which the name Massilia aurea sp. nov. is proposed. The type strain is AP13(T) (=CECT 7142(T)=CCM 7363(T)=DSM 18055(T)=JCM 13879(T)). (+info)