scholarly journals Positive control of sulphate reduction in Escherichia coli. Isolation, characterization and mapping of cysteineless mutants of E. coli K 12

1968 ◽  
Vol 110 (3) ◽  
pp. 589-595 ◽  
Author(s):  
M. C. Jones-Mortimer
Keyword(s):  
Escherichia Coli ◽  
Salmonella Typhimurium ◽  
Genetic Map ◽  
Genetic Data ◽  
Positive Control ◽  
Sulphate Reduction ◽  
Biochemical Data ◽  
E Coli ◽  
K 12 ◽  
Single Enzyme

To determine to what extent the biosynthesis of cysteine in Escherichia coli resembles that in Salmonella typhimurium, the following experiments were performed. (1) Mutants of E. coli K 12 deficient in the biosynthesis of cysteine were isolated. (2) These mutants were classified by nutritional and biochemical criteria; some mutants lacked a single enzyme of sulphate reduction, other mutants appeared to lack two or more enzymes. (3) The genetic map predicted from the biochemical data alone is shown to be incorrect, and an alternative map, consistent with the genetic data, is proposed for the cys mutants of E. coli.

scholarly journals HosA, a Member of the SlyA Family, Regulates Motility in Enteropathogenic Escherichia coli

2005 ◽  
Vol 73 (3) ◽  
pp. 1684-1694 ◽  
Author(s):  
Maria-José Ferrándiz ◽  
Keith Bishop ◽  
Paul Williams ◽  
Helen Withers
Keyword(s):  
Escherichia Coli ◽  
Transcriptional Regulators ◽  
Positive Control ◽  
Broth Culture ◽  
Wild Type ◽  
Mobility Shift ◽  
E Coli ◽  
Protein Levels ◽  
K 12 ◽  
Electrophoretic Mobility Shift Assays

ABSTRACT In enteropathogenic and enterohemorraghic Escherichia coli (EPEC and EHEC), two members of the SlyA family of transcriptional regulators have been identified as SlyA. Western blot analysis of the wild type and the corresponding hosA and slyA deletion mutants indicated that SlyA and HosA are distinct proteins whose expression is not interdependent. Of 27 different E. coli strains (EPEC, EHEC, enteroinvasive, enteroaggregative, uropathogenic, and commensal) examined, 14 were positive for both genes and proteins. To investigate hosA expression, a hosA::luxCDABE reporter gene fusion was constructed. hosA expression was significantly reduced in the hosA but not the slyA mutant and was influenced by temperature, salt, and pH. In contrast to SlyA, HosA did not activate the cryptic E. coli K-12 hemolysin ClyA. Mutation of hosA did not influence type III secretion, the regulation of the LEE1 and LEE4 operons, or the ability of E2348/69 to form attaching-and-effacing lesions on intestinal epithelial cells. HosA is, however, involved in the temperature-dependent positive control of motility on swim plates and regulates fliC expression and FliC protein levels. In electrophoretic mobility shift assays, purified HosA protein bound specifically to the fliC promoter, indicating that HosA directly modulates flagellin expression. While direct examination of flagellar structure and the motile behavior of individual hosA cells grown in broth culture at 30°C did not reveal any obvious differences, hosA mutants, unlike the wild type, clumped together, forming nonmotile aggregates which could account for the markedly reduced motility of the hosA mutant on swim plates at 30°C. We conclude that SlyA and HosA are independent transcriptional regulators that respond to different physicochemical cues to facilitate the environmental adaptation of E. coli.

scholarly journals Positive control of sulphate reduction in Escherichia coli. The nature of the pleiotropic cysteineless mutants of E. coli K 12

1968 ◽  
Vol 110 (3) ◽  
pp. 597-602 ◽  
Author(s):  
M. C. Jones-Mortimer
Keyword(s):  
Escherichia Coli ◽  
Mutant Allele ◽  
Positive Control ◽  
Wild Type Allele ◽  
Wild Type ◽  
E Coli ◽  
Type Allele ◽  
K 12 ◽  
Sulphite Reductase

1. The function of the wild-type alleles of the pleiotropic mutants cysB and cysE of Escherichia coli was investigated. 2. The wild-type allele cysB+ is dominant to the mutant allele cysB in stable and transient heterozygotes. 3. The wild-type allele cysE+ is dominant to the mutant allele cysE, as predicted. 4. Sulphur-starved cultures of cysB or cysE strains contain less than 0·2nmole of free cysteine/mg. dry wt. 5. Complementation in vitro is not observed between extracts of cysB mutants and mutants lacking sulphite reductase only. 6. A scheme, involving positive control of the enzymes of sulphate activation and reduction, is suggested to account for the control of cysteine biosynthesis.

scholarly journals DELETION AND AMBER MUTANTS OF fla LOCI IN ESCHERICHIA COLI K-12

Genetics ◽  
1976 ◽  
Vol 84 (3) ◽  
pp. 403-421
Author(s):  
Hisato Kondoh ◽  
Haruo Ozeki
Keyword(s):  
Escherichia Coli ◽  
High Temperature ◽  
Genetic Map ◽  
Screening Method ◽  
The Other ◽  
Rapid Screening ◽  
E Coli ◽  
Flagellar Filament ◽  
Rapid Screening Method ◽  
K 12

ABSTRACT A rapid screening method for amber fla mutants of E. coli was devised and many mutants were obtained. In addition, strains with deletions of the fla genes in the his-uvrC region were isolated from high-temperature survivors of a λcI857 lysogen in which the prophage is located between his and fla. Utilizing these mutants, eleven fla genes (I-XI) and one hag gene were identified in the his-uvrc region, in the following order: his-supD-I-II-(III, IV)-V-(VI, VII)-VIII-IX-hag-(X, XI)-uvrC. The fla genes X and XI and hag are located at about 42.5 min and the other fla genes at about 43.0 min on the E. coli genetic map (Bachmann, Low and Taylor 1976). Mutants of fla gene X showed a slight sensitivity to chi phage, although they lack the flagellar filament.

scholarly journals Apramycin resistance plasmids inEscherichia coli: possible transfer toSalmonella typhimuriumin calves

1992 ◽  
Vol 108 (2) ◽  
pp. 271-278 ◽  
Author(s):  
J. E. B. Hunter ◽  
J. C. Shelley ◽  
J. R. Walton ◽  
C. A. Hart ◽  
M. Bennett
Keyword(s):  
Escherichia Coli ◽  
Salmonella Typhimurium ◽  
High Frequency ◽  
Inescherichia Coli ◽  
Gene Encoding ◽  
E Coli ◽  
Resistance Plasmids ◽  
Effect Of Treatment ◽  
K 12

SUMMARYAn outbreak of salmonellosis in calves was monitored for persistence ofSalmonella typhimuriumexcretion in faeces and the effect of treatment with apramycin. Prior to treatment apramycin-resistantEscherichia coliwere present but allS. typhimuriumisolates were sensitive. Following the treatment of six calves with apramycin, apramycin-resistantS. typhimuriumwere isolated from two treated calves and one untreated calf. Plasmid profiles ofE. coliandS. typhimuriumwere compared and plasmids conferring resistance to apramycin and several other antibiotics were transferred by conjugationin vitrofrom calfE. coliandS. typhimuriumisolates toE. coliK-12 and fromE. colitoS. typhimurium. The plasmids conjugated with high frequencyin vitrofromE. colitoS. typhimurium, and hybridized to a DNA probe specific for the gene encoding aminoglycoside acetyltransferase 3-IV (AAC(3)-IV) which confers resistance to apramycin, gentamicin, netilmicin and tobramycin.

scholarly journals Unexpected Phytostimulatory Behavior for Escherichia coli and Agrobacterium tumefaciens Model Strains

2013 ◽  
Vol 26 (5) ◽  
pp. 495-502 ◽  
Author(s):  
Vincent Walker ◽  
Maxime Bruto ◽  
Floriant Bellvert ◽  
René Bally ◽  
Daniel Muller ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Agrobacterium Tumefaciens ◽  
Nitrite Reductase ◽  
Azospirillum Brasilense ◽  
High Performance ◽  
Positive Control ◽  
Shoot Biomass ◽  
E Coli ◽  
K 12 ◽  
The Impact

Plant-beneficial effects of bacteria are often underestimated, especially for well-studied strains associated with pathogenicity or originating from other environments. We assessed the impact of seed inoculation with the emblematic bacterial models Agrobacterium tumefaciens C58 (plasmid-cured) or Escherichia coli K-12 on maize seedlings in nonsterile soil. Compared with the noninoculated control, root biomass (with A. tumefaciens or E. coli) and shoot biomass (with A. tumefaciens) were enhanced at 10 days for ‘PR37Y15’ but not ‘DK315’, as found with the phytostimulator Azospirillum brasilense UAP-154 (positive control). In roots as well as in shoots, Agrobacterium tumefaciens and E. coli triggered similar (in PR37Y15) or different (in DK315) changes in the high-performance liquid chromatography profiles of secondary metabolites (especially benzoxazinoids), distinct from those of Azospirillum brasilense UAP-154. Genome sequence analysis revealed homologs of nitrite reductase genes nirK and nirBD and siderophore synthesis genes for Agrobacterium tumefaciens, as well as homologs of nitrite reductase genes nirBD and phosphatase genes phoA and appA in E. coli, whose contribution to phytostimulation will require experimental assessment. In conclusion, the two emblematic bacterial models had a systemic impact on maize secondary metabolism and resulted in unexpected phytostimulation of seedlings in the Azospirillum sp.-responsive cultivar.

scholarly journals Structural genes for nitrate-inducible formate dehydrogenase in Escherichia coli K-12.

Genetics ◽  
1990 ◽  
Vol 125 (4) ◽  
pp. 691-702 ◽  
Author(s):  
B L Berg ◽  
V Stewart
Keyword(s):  
Escherichia Coli ◽  
Nitrate Reductase ◽  
Formate Dehydrogenase ◽  
Recombinant Dna ◽  
Structural Genes ◽  
Respiratory Pathway ◽  
E Coli ◽  
Formate Oxidation ◽  
Operon Expression ◽  
K 12

Abstract Formate oxidation coupled to nitrate reduction constitutes a major anaerobic respiratory pathway in Escherichia coli. This respiratory chain consists of formate dehydrogenase-N, quinone, and nitrate reductase. We have isolated a recombinant DNA clone that likely contains the structural genes, fdnGHI, for the three subunits of formate dehydrogenase-N. The fdnGHI clone produced proteins of 110, 32 and 20 kDa which correspond to the subunit sizes of purified formate dehydrogenase-N. Our analysis indicates that fdnGHI is organized as an operon. We mapped the fdn operon to 32 min on the E. coli genetic map, close to the genes for cryptic nitrate reductase (encoded by the narZ operon). Expression of phi(fdnG-lacZ) operon fusions was induced by anaerobiosis and nitrate. This induction required fnr+ and narL+, two regulatory genes whose products are also required for the anaerobic, nitrate-inducible activation of the nitrate reductase structural gene operon, narGHJI. We conclude that regulation of fdnGHI and narGHJI expression is mediated through common pathways.

PCR for the Specific Detection of an Escherichia coli O157:H7 Laboratory Control Strain

2015 ◽  
Vol 78 (9) ◽  
pp. 1738-1744 ◽  
Author(s):  
MICHAEL KNOWLES ◽  
DOMINIC LAMBERT ◽  
GEORGE HUSZCZYNSKI ◽  
MARTINE GAUTHIER ◽  
BURTON W. BLAIS
Keyword(s):  
Escherichia Coli ◽  
Pathogenic Bacteria ◽  
Control Measure ◽  
Positive Control ◽  
Food Microbiology ◽  
Escherichia Coli O157 ◽  
Control Strain ◽  
E Coli ◽  
Signature Sequences ◽  
Materials Used

Control strains of bacterial pathogens such as Escherichia coli O157:H7 are commonly processed in parallel with test samples in food microbiology laboratories as a quality control measure to assure the satisfactory performance of materials used in the analytical procedure. Before positive findings can be reported for risk management purposes, analysts must have a means of verifying that pathogenic bacteria (e.g., E. coli O157:H7) recovered from test samples are not due to inadvertent contamination with the control strain routinely handled in the laboratory environment. Here, we report on the application of an in-house bioinformatic pipeline for the identification of unique genomic signature sequences in the development of specific oligonucleotide primers enabling the identification of a common positive control strain, E. coli O157:H7 (ATCC 35150), using a simple PCR procedure.

scholarly journals ATIVIDADE ANTIMICROBIANA DE MICRORGANISMOS ISOLADOS DE GRÃOS DE KEFIR

2018 ◽  
Vol 19 (0) ◽  
Author(s):  
Priscila Alves Dias ◽  
Daiani Teixeira Silva ◽  
Cláudio Dias Timm
Keyword(s):  
Escherichia Coli ◽  
Staphylococcus Aureus ◽  
Listeria Monocytogenes ◽  
Salmonella Typhimurium ◽  
Salmonella Enterica ◽  
Escherichia Coli O157 ◽  
E Coli

Resumo Kefir é o produto da fermentação do leite pelos grãos de kefir. Esses grãos contêm uma mistura simbiótica de bactérias e leveduras imersas em uma matriz composta de polissacarídeos e proteínas. Muitos benefícios à saúde humana têm sido atribuídos ao kefir, incluindo atividade antimicrobiana contra bactérias Gram positivas e Gram negativas. A atividade antimicrobiana de 60 microrganismos isolados de grãos de kefir, frente à Escherichia coli O157:H7, Salmonella enterica subsp. enterica sorotipos Typhimurium e Enteritidis, Staphylococcus aureus e Listeria monocytogenes, foi estudada através do teste do antagonismo. A ação antimicrobiana dos sobrenadantes das bactérias ácido-lácticas que apresentaram atividade no teste do antagonismo foi testada. O experimento foi repetido usando sobrenadantes com pH neutralizado. Salmonella Typhimurium e Enteritidis sobreviveram por 24 horas no kefir em fermentação. E. coli O157:H7, S. aureus e L. monocytogenes foram recuperados até 72 horas após o início da fermentação. Todos os isolados apresentaram atividade antimicrobiana contra pelo menos um dos patógenos usados no teste do antagonismo. Sobrenadantes de 25 isolados apresentaram atividade inibitória e três mantiveram essa atividade com pH neutralizado. As bactérias patogênicas estudadas sobreviveram por tempo superior àquele normalmente utilizado para a fermentação do kefir artesanal, o que caracteriza perigo em potencial para o consumidor quando a matéria-prima não apresentar segurança sanitária. Lactobacillus isolados de grãos de kefir apresentam atividade antimicrobiana contra cepas de E. coli O157:H7, Salmonella sorotipos Typhimurium e Enteritidis, S. aureus e L. monocytogenes além daquela exercida pela diminuição do pH.

Potentiation by L-cysteine of the bactericidal effect of hydrogen peroxide in Escherichia coli

1982 ◽  
Vol 152 (1) ◽  
pp. 81-88
Author(s):  
E H Berglin ◽  
M B Edlund ◽  
G K Nyberg ◽  
J Carlsson
Keyword(s):  
Escherichia Coli ◽  
Hydrogen Peroxide ◽  
Metal Ion ◽  
Chelating Agent ◽  
Fold Increase ◽  
Bactericidal Effect ◽  
Anaerobic Conditions ◽  
Dna Breakage ◽  
E Coli ◽  
K 12

Under anaerobic conditions an exponentially growing culture of Escherichia coli K-12 was exposed to hydrogen peroxide in the presence of various compounds. Hydrogen peroxide (0.1 mM) together with 0.1 mM L-cysteine or L-cystine killed the organisms more rapidly than 10 mM hydrogen peroxide alone. The exposure of E. coli to hydrogen peroxide in the presence of L-cysteine inhibited some of the catalase. This inhibition, however, could not fully explain the 100-fold increase in hydrogen peroxide sensitivity of the organism in the presence of L-cysteine. Of other compounds tested only some thiols potentiated the bactericidal effect of hydrogen peroxide. These thiols were effective, however, only at concentrations significantly higher than 0.1 mM. The effect of L-cysteine and L-cystine could be annihilated by the metal ion chelating agent 2,2'-bipyridyl. DNA breakage in E. coli K-12 was demonstrated under conditions where the organisms were killed by hydrogen peroxide.

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