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1.
In this study, sStrain SK‐1T, a novel gram‐positive, pleomorphic, rod‐shaped, non‐spore forming, non‐motile organism, designated SK‐1T, was isolated from human gingival sulcus and found to produce acetic acid, propionic acid, lactic acid, and succinic acid as end products of glucose fermentation. Strain SK‐1T is most closely related to Pseudopropionibacterium (Propionibacterium) propionicum with sequence homologies of the 16S rRNA and RNA polymerase β subunit (rpoB) genes of 96.6% and 93.1%, respectively. The genomic DNA G + C content of the isolate was 61.8 mol%. On the basis of the sequence data of the 16S rRNA and housekeeping (rpoB) genes, a novel taxon is here proposed, Pseudopropionibacterium rubrum sp. nov. (type strain SK‐1T = JCM 31317T = DSM 100122T). The 16S rRNA and rpoB gene sequences of strain SK‐1T have been deposited in the DDBJ under the accession numbers LC002971 and LC102236, respectively. 相似文献
2.
In bacteria, guanosine (penta)tetra-phosphate ([p]ppGpp) is essential for controlling intracellular metabolism that is needed to adapt to environmental changes, such as amino acid starvation. The (p)ppGpp 0 strain of Bacillus subtilis, which lacks (p)ppGpp synthetase, is unable to form colonies on minimal medium. Here, we found suppressor mutations in the (p)ppGpp 0 strain, in the purine nucleotide biosynthesis genes, prs, purF and rpoB/C, which encode RNA polymerase core enzymes. In comparing our work with prior studies of ppGpp 0 suppressors, we discovered that methionine addition masks the suppression on minimal medium, especially of rpoB/ C mutations. Furthermore, methionine addition increases intracellular GTP in rpoB suppressor and this effect is decreased by inhibiting GTP biosynthesis, indicating that methionine addition activated GTP biosynthesis and inhibited growth under amino acid starvation conditions in (p)ppGpp 0 backgrounds. Furthermore, we propose that the increase in intracellular GTP levels induced by methionine is due to methionine derivatives that increase the activity of the de novo GTP biosynthesis enzyme, GuaB. Our study sheds light on the potential relationship between GTP homeostasis and methionine metabolism, which may be the key to adapting to environmental changes. 相似文献
3.
Three strains TKU9, TKU49 and TKU50 T, were isolated from the oral cavities of chimpanzees ( Pan troglodytes). The isolates were all gram‐positive, facultative anaerobic cocci that lacked catalase activity. Analysis of partial 16S rRNA gene sequences showed that the most closely related species was Streptococcus infantis (96.7%). The next most closely related species to the isolates were S. rubneri, S. mitis, S. peroris and S. australis (96.6 to 96.4%). Based on the rpoB and gyrB gene sequences, TKU50 T was clustered with other member of the mitis group. Enzyme activity and sugar fermentation patterns differentiated this novel bacterium from other members of the mitis group streptococci. The DNA G + C content of strain TKU50 T was 46.7 mol%, which is the highest reported value for members of the mitis group (40–46 mol%). On the basis of the phenotypic characterization, partial 16S rRNA gene and sequences data for two housekeeping gene ( gyrB and rpoB), we propose a novel taxa, S. panodentis for TKU 50 T (type strain = CM 30579 T = DSM 29921 T), for these newly described isolates. 相似文献
4.
Summary When plasmids carrying leucine genes of Bacillus subtilis 168 were isolated from a restriction and modification deficient (r -m -) strain and used for transformation of a restricting strain B. subtilis 168 leu recE4, the number of transformants was greatly reduced. Transformation of a rec
+ strain (transformation by integration of the donor DNA into the chromosome) with the plasmids was not affected irrespective of whether the recipient carried the r + or r - phenotype. These results show that the plasmid-mediated transformation is subject to the host controlled restriction and suggest that r -m - strains should be used for construction of recombinant DNA molecules in B. subtilis 168. 相似文献
5.
Extensive genetic variability resulting from a high mutation rate and frequent recombination is a characteristic of Helicobacter pylori. Its average mutation rate is 1 × 10 −6, similar to that of Escherichia coli mutator strains. Few genes involved in DNA repair have been functionally characterized in H. pylori. In E. coli, the DNA glycosylase MutY is a part of the base excision repair system. The H. pylori mutY homolog HP0142 was analyzed in this study. HP0142 was disrupted by inserting a kanamycin resistance cassette. Mutation rates
were determined by measuring the frequency of point mutations in rpoB conferring resistance against rifampicin. Inactivation of mutY in H. pylori resulted in an increase of the mutation frequency by a factor of up to 34. Sequence analysis of rpoB in rifampicin-resistant clones selected from the mutY mutant showed a modest increase of G:C/T:A transversions in comparison to clones selected from wild type strains. In contrast,
inactivation of mutY had a profound impact on the distribution of mutations within rpoB. This finding suggests that the efficiency with which mutY prevents transversions is strongly dependent upon the sequence context. Inactivation of mutY was associated with a stationary phase fitness deficit in competitive cultures with the wild type strain. 相似文献
6.
Lethal and mutagenic effects of nitrous acid and UV radiation on Mycobacterium phlei were studied Three auxotrophic strains of the PA strain of Mycobacterium phlei were obtained: ala -, his -, and gly - (ser -) INH r Bods of the his - strain grown in liquid media are longer to filamentous as compared with cells of the prototrophic PA strain grown in the
same media, whereas cells of the gly - (ser -) INH r mutant are shorter to coccobacillary. Cells of the ala - strain are characterized by their various length from normal to coccobacillary. The auxotrophic strains obtained differ from
each other by a frequency of spontaneous reversions to prototrophy. The his - strain is the most stable, a frequency of spontaneous reversions to prototrophy being 10 -9. The gly - (ser -) INH r strain reverts spontaneously to prototrophy with a frequency of 10 -8 to 10 -7. The ala - strain spontaneously reverting with a frequency of 10 -5 is the most labile. The auxotrophic mutants obtained do not differ from the original prototrophic strain in the other properties
studied.
A change in a frequency of INH and STM-resistant mutants was also studied. It was found that under the influence of UV radiation
a frequency of INH-resistant mutants increases 43 to 80 fold as compared with a frequency of spontaneous mutations, this latter
being about 2.6 × 10 -6. No substantial increase in a frequency of STM-resistant mutants was found using UV irradiation under the given experimental
conditions; their spontaneous frequency equals to 9.0 × 10 -9 to 2.0 X 10 -8. 相似文献
7.
Summary Strains with both uvrA6 and the lex-1 mutations are more sensitive to ultraviolet light (UV) than isogenic strains with only one of the mutations. The lex
- uvrA -double mutant has the same sensitivity to methyl-methane-sulfonate as the lex
- uvrA +single mutant. UV-irradiated cultures of lex
- uvrA +and lex
- uvrA -strains do not produce more streptomycinresistant mutants per survivor than unirradiated cultures. UV-irradiated cultures of a lex
+ uvrA -strain produce large yields of mutants at both low (4 ergs/mm 2) and high (25 ergs/mm 2) doses of UV compared with the lex
+ uvrA + strain which produce an intermediate yield of mutants at 25 ergs/mm 2, and a small yield at 4 ergs/mm 2, not significantly greater than unirradiated cultures. A dose of UV which does not induce mutations in strains with the lex-1 mutation produces only a small decrease in DNA synthesis in the lex
- uvrA +strain. The results are interpreted to mean that the lex-1 mutation probably does not affect the same pathway of DNA repair as the uvrA
+product (i.e. excision of thymine dimers), and that the absence of UV-induced mutations in irradiated cultures of lex
-strains is probably not due to a cessation of DNA replication. 相似文献
8.
Summary The nature of the transformation process in E. coli was studied by investigating various factors which affect the efficiency of transformation. CaCl 2 treatment of the recipient cells is absolutely necessary for transformation and the optimum concentration was found to be 30 mM. The efficiency of transformation is dependent upon temperature during incubation of the recipient cells with DNA. The efficiency is also affected by the molecular weight of donor DNA used. Sheared DNA with molecular weights ranging from 10 to 30x10 6 daltons was most efficient, increasing the number of transformants by a factor of 5 to 10 as compared to unsheared DNA. The intracellular status of recB-recC DNase (ATP-dependent DNase) is another important factor which determines the transformability of E. coli K12. This was shown by demonstrating that a recB
-
recC
-
sbcA
- strain was transformable as well as the previously demonstrated recB
-
recC
-
sbcB
-
strain. Therefore, it seems reasonable to conclude that the E. coli K12 strain is transformable if the ATP-dependent DNase is absent or diminished in function and a state of recombinational proficiency exists. 相似文献
9.
Summary Two strains of the soybean endosymbiont Bradyrhizobium japonicum, USDA 110 and 61 A101 C, were mutagenized with transposon Tn 5. After plant infection tests of a total of 6,926 kanamycin and streptomycin resistant transconjugants, 25 mutants were identified that are defective in nodule formation (Nod -) or nitrogen fixation (Fix -). Seven Nod - mutants were isolated from strain USDA 110 and from strain 61 A101 C, 4 Nod - mutants and 14 Fix - mutants were identified. Subsequent auxotrophic tests on these symbiotically defective mutants identified 4 His - Nod - mutants of USDA 110. Genomic Southern analysis of the 25 mutants revealed that each of them carried a single copy of Tn 5 integrated in the genome. Three 61 A101 C Fix - mutants were found to have vector DNA co-integrated along with Tn 5 in the genome. Two independent DNA regions flanking Tn 5 were cloned from the three nonauxotrophic Nod - mutants and one His -Nod - mutant of USDA 110. Homogenotization of the cloned fragments into wild-type strain USDA 110 and subsequent nodulation assay of the resulting homogenotes confirmed that the Tn 5 insertion was responsible for the Nod - phenotype. Partial EcoR1 restriction enzyme maps around the Tn 5 insertion sites were generated. Hybridization of these cloned regions to the previously cloned nod regions of R. meliloti and nif and nod regions of B. japonicum USDA 110 showed no homology, suggesting that these regions represent new symbiotic clusters of B. japonicum. 相似文献
10.
Summary In Rhizobium phaseoli strain 8002, the 190 Md plasmid pRP2JI which determines the ability to produce nitrogen-fixing nodules on Phaseolus beans (Nod + Fix +) and the production of melanin on L-tyrosine-containing media (Mel +), was shown to be transmissible by conjugation to other Rhizobium strains. When pRP2JI was transferred to Nod - strains of R. leguminosarum (which normally nodulates peas) the transconjugants gained the ability to nodulate Phaseolus beans and to make melanin.Out of 187 derivatives of strain 8002 carrying pRP2JI plasmids into which the transposon Tn5 had been inserted, six were Fix - Nod + Mel +, one was Fix - Nod + Mel - and four were Fix + Nod + Mel -. Three other derivatives of strain 8002 were Nod - Mel -; these had suffered deletions of c 30 Md in pRP2JI. Thus the genes for melanin production and nodulation appear to be closely linked, but melanin production is not necessary for the induction of nitrogen-fixing nodules on Phaseolus beans. 相似文献
11.
Summary A Bsu168-specific restriction deficient (r
168
-
) mutant of Bacillus subtilis Marburg 168 was transformed to be BsuR-specific restriction proficient (r
R
+
) with B. subtilis R DNA as efficiently as the Bsu168-specific restriction proficient (r
168
+
) parental strain ( hsrM
+, hsdR
-).We constructed r
R
+
m
R
+
r
168
+
m
168
+
strain (ISMR 4), r
R
+
m
R
+
r
168
-
m
168
+
strain (ISR 11) and r
R
+
m
R
+
r
168
-
m
168
-
strain (ISR 6) from strain 101 (r
168
+
m
168
+
), strain 1012 (r
168
-
m
168
+
) and strain RM125 (r
168
-
m
168
-
), respectively by transformation with B. subtilis R DNA, and tested their restriction and modification activities on phage 105C. The results show that the sites recognized by Bsu168-specific restriction and modification enzymes and the sites recognized by BsuR-specific ones are not overlapping.We conclude that the Bsu168-modification and restriction system and the BsuR-modification and restriction system are controlled independently by two distinct sets of genes in the r
R
+
m
R
+
transformant of r
168
+
m
168
+
strain B. subtilis 168. 相似文献
12.
Summary A strain of Phanerochaete chrysosporium, designated strain K-3, was isolated from a monosporous conidiospore culture of Sporotrichum pulverulentum. This strain produces fruit bodies with only four sterigmata. From basidiospores of this culture, the homokaryotic strain 31 with high lignin degrading capacity was selected and subjected to ultraviolet irradiation to obtain cellulase deficient (Cel -) strains. By cross-breeding one of these Cel - variants with selected Cel + homokaryotic strains from K-3 with high lignin degrading capacity, new Cel - mutants were isolated which exceeded K-3 in their capacity to degrade lignin.The Cel - strains were totally incapable of degrading cellulose but were able to degrade xylan. Evolution of 14CO 2 from 14C-ring-labelled synthetic lignin a dehydrogenation polymerizate (DHP) was used to screen for strains with high lignin degrading capacity.Studies of weight loss on birch and spruce wood revealed that the weight losses caused by strain K-3 exceeded, in all cases, those caused by the Cel - strains. However, higher lignin losses in birch wood were obtained with several of the Cel - strains than with the K-3 strain. After 2 weeks, one strain caused a lignin loss in birch wood of 21% of the initial amount of lignin, while with another strain there was, after 3 weeks incubation, a 28.5% decrease in the lignin content. 相似文献
13.
Summary Slow-growing ( inl
+/-) spontaneous mutants have been isolated from an inositol requiring ( inl) strain of Neurospora crassa that produces defective myo-inositol-1-phosphate synthase (MIPS), the enzyme responsible for the production of inositol-1-phosphate from glucose-6-phosphate. The defective enzyme has some residual activity. In the inl
+/- strain the synthesis of the defective enzyme is enhanced, which enables the strain to grow slowly on minimal medium. The mutation ( opi1) responsible for the partial inositol independence segregates independently from the inositol locus, and suppresses the inositolless character by overproduction of defective MIPS. opi1 acting upon the wild type ( inl
+) allele increases MIPS production and causes inositol excretion. 相似文献
14.
Pseudomonas sp. strain 267 isolated from soil promoted growth of different plants under field conditions and enhanced symbiotic nitrogen fixation in clover under gnotobiotic conditions. This strain produced pyoverdine-like compound under low-iron conditions and secreted vitamins of the B group. The role of fluorescent siderophore production in the beneficial effect of strain 267 on nodulated clover plants was investigated. Several non-fluorescent (Pvd -) Tn5 insertion mutants of Pseudomonas sp. strain 267 were isolated and characterized. The presence of Tn5 insertions was confirmed by Southern analysis of EcoRI digested genomic DNA of each derivative strain. The siderophore-negative mutants were compared to the parental strain with respect to their growth promotion of nodulated clover infected with Rhizobium leguminosarum bv. trifolii 24.1. We found that all isolated Pvd - mutants stimulated growth of nodulated clover plants in a similar manner to the parental strain. No consistent differences were observed between strain 267 and Pvd - derivatives strains with respect to their plant growth promotion activity under gnotobiotic conditions.Dr Deryto died in august 1994 相似文献
15.
A Gram-positive, nitrogen-fixing and endospore-forming strain, designated P121T, was isolated from the gut of the armored catfish (Parotocinclus maculicauda) and identified as a member of the genus Paenibacillus based on the sequences of the 16S rRNA encoding gene, rpoB, gyrB and nifH genes and phenotypic analyses. The most closely related species to strain P121T were Paenibacillus rhizoplanae DSM 103993T, Paenibacillus silagei DSM 101953T and Paenibacillus borealis DSM 13188T, with similarity values of 98.9, 98.3 and 97.6%, respectively, based on 16S rRNA gene sequences. Genome sequencing revealed a genome size of 7,513,698 bp, DNA G?+?C content of 53.9 mol% and the presence of the structural nitrogenase encoding genes (nifK, nifD and nifH) and of other nif genes necessary for nitrogen fixation. Digital DNA-DNA hybridization (dDDH) experiments and average nucleotide identity (ANI) analyses between strain P121T and the type strains of the closest species demonstrated that the highest values were below the thresholds of 70% dDDH (42.3% with P. borealis) and 95% ANI (84.28% with P. silagei) for bacterial species delineation, indicating that strain P121T represents a distinct species. Its major cellular fatty acid was anteiso-C15:0 (42.4%), and the major isoprenoid quinone was MK-7. Based on physiological, genomic, biochemical and chemotaxonomic characteristics, we propose that strain P121T represents a novel species for which the name Paenibacillus piscarius sp. nov. is proposed (type strain?=?DSM 25072?=?LFB-Fiocruz 1636). 相似文献
16.
Summary A collection of 95 independent, spontaneously-occurring mutants carrying amber lesions that affect expression of the gene, rpoB, has been isolated (see accompanying paper (Nene and Glass 1982)). Certain rpoB amber mutations act in trans, preventing a functional allele present on an F plasmid from acting at high temperature. Two such temperature-sensitive rpoB(Am) strains are shown to produce large, N-terminal amber fragments. The possibility that these truncated polypeptides are the cause of this trans-dominant conditional-lethal phenotype is supported by analysis of fragment levels in thermoresistant survivors: the nonsense fragments are degraded at a significantly faster rate (half-lives 1.4- to 2.6-fold reduced) in Ts + derivatives likely to carry second-site mutations within rpoB. We suggest that the fragments interfere with RNA polymerase function by interacting with one or more of the polymerase subunits. 相似文献
17.
Summary A 15 kilobase HindIII fragment of Klebsiella pneumoniae DNA containing the glnA gene was cloned into the plasmid vector pACYC184. The resulting plasmid, pFB51, complements glnA
- mutations in Escherichia coli and K. pneumoniae. pFB51 also complements the GlnR phenotype of a Klebsiella pneumoniae gln regulatory mutant (KP5060) defined by the restoration of Hut + and Nif + (histidine utilization and nitrogen fixation) phenotypes to this strain. Three recombinant plasmids containing subsegments of the 15 kb HindIII fragment were derived from pFB51. Plasmid pFB514 which contains a spontaneous 4 kb delection of K. pneumoniae DNA from pFB51 is more stable than pFB51 and is still able to complement glnA
- mutations and the GlnR - phenotype of KP5060. Plasmids pFB53 and pFB54, which contain a 6.5 kb SalI DNA fragment from pFB51 recloned into pACYC184 in opposite orientations, complement glnA
- mutations but not the GlnR - phenotype of KP5060. Plasmids pFB514 and pFB53 were mutagenized by transposon Tn5 resulting in a total of 92 Tn5 insertions in the cloned fragments. Utilizing these insertion mutations, a correlated physical and genetic map was constructed by determining the physical location of each Tn5 insertion and by analyzing the ability of each Tn5 mutated plasmid to complement a glnA
- strain of E. coli and a glnA
- GlnR - strain of K. pneumoniae. Two classes of Tn5 insertions with an altered Gln phenotpye were obtained. One cluster of insertions spanning a 1.3 kb region abolished complementation of the glnA
- mutations. A second 2 kb cluster of Tn5 insertions, immediately adjacent to the first cluster, abolished the ability of pFB514 plasmid to complement the GlnR - phenotype, while glnA
- complementation was unaffected. We propose that the second cluster of Tn5 insertions define a DNA region coding for a positive regulatory factor for nitrogen fixation ( nif) and histidine utilization ( hut) genes ( glnR). 相似文献
18.
The spontaneous antimicrobial surfactant-resistant mutant, Escherichia coli OW66, has been isolated, and its physiological properties have been characterized in our previous paper (Ishikawa et al.,
J Appl Microbiol 92:261–268, 2002b). This report revealed that strain OW66 had seven mutations in their chromosomal DNA by comparative genomic hybridization
microarray, and that their alternative functions were involved in cell resistance to antimicrobial surfactants. These mutations
were located in oppB, ydcR, IVR( vacJ- yfdC), rpoN, rpoB, rpoC, and soxR. Furthermore, seven of the single-mutated isogenic strains and seven of the six-mutated isogenic strains were constructed
from strains OW6 (NBRC106482) and OW66, respectively, through homologous recombination, and their resistances to an antimicrobial
surfactant were measured using the minimum inhibitory concentration method. These results revealed that all six-mutated strains
were more sensitive than strain OW66, and that the soxR66 mutation was independently involved in antimicrobial surfactant resistance of E. coli cells. Expression of soxR66 and soxS was increased in both strains OW66 and OW6- soxR66 without the surfactant treatment by the quantitative real time-polymerase chain reaction analysis, compared with strain OW6.
Two-dimensional polyacrylamide gel electrophoresis analysis also revealed that some proteins in the soxRS regulon, including Mn-SOD, were overexpressed in both strains OW66 and OW6- soxR66. These results indicate that the soxR66 mutation leads to the constitutive expression of the soxRS regulon, resulting in the acquired resistance of E. coli cells to an antimicrobial surfactant. 相似文献
19.
Summary The wild-type heterocystous and nitrogen-fixing ( Het
+
Nif
+) N. muscorum and its non-heterocystous non-nitrogen-fixing ( Het
-
Nif
-) mutant strain both fail to grow in different inorganic nitrogen media containing 1 mM methylamine hydrochloride (MA). Mutants of the Het
+
Nif
+ and Het
-
Nif
- parents resistant to growth inhibition by 5 mM MA and thus designated as MA
R strains were isolated with a frequency of 2.5(±2.4)×10 6. A MA
R strains of the Het
+
Nif
+ and a MA
R strain of the Het
-
Nif
- parent were characterized for growth, heterocyst formation and acetylene reducing activity in the presence and absence of methylamine in N 2 medium. The Het
+
Nif
+
MA
R strain grows better in MA containing than in MA-free N 2 medium, and all cultures grown with MA are found to lack both acetylene reducing activity and heterocyst. The Het
-
Nif
-
MA
R strain shows good growth in MA-containing N 2 medium but no growth in MA-free N 2 medium. Furthermore, both the Het
+
Nif
+
MA
R and Het
-
Nif
-
MA
R strains show better growth in the presence than in the absence of MA in NO
3
-
and NH
4
+
media. These results appear to suggest that the MA
R phenotype in N. muscorum is due to the metabolic utilization of the ammonium analog as a nitrogen source. 相似文献
20.
Summary A T6 s RecA - strain carrying a lac proB deletion and F ts
lac
+ was challenged with phage T6 and survivors which were both T6 r and Lac + at 42° were tested for fertility. Among these were a number of Hfr strains which had their points of origin at or near the tsx locus and which still carried the recA allele. These arose in comparable frequencies in the RecA - strain and in a Rec + analogue. We conclude that such integration does not require the RecA function. The rate of chromosome transfer was similar in one such RecA - Hfr and its Rec + derivative; the yield of recombinants from the RecA - strain was slightly lower than from its Rec + derivative. 相似文献
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