scholarly journals A Quantitative Method for Determining Soil Populations of Streptomyces and Differentiating Potential Potato Scab-Inducing Strains

Plant Disease ◽  
1998 ◽  
Vol 82 (6) ◽  
pp. 631-638 ◽  
Author(s):  
Kenneth L. Conn ◽  
Edlira Leci ◽  
Giora Kritzman ◽  
George Lazarovits
Keyword(s):  
Potato Scab ◽  
Colony Morphology ◽  
Malt Extract ◽  
Facilitated Diffusion ◽  
Thaxtomin A ◽  
Streptomyces Spp ◽  
Plastic Bags ◽  
Large Numbers ◽  
History Of ◽  
Layer Chromatography

A procedure is described for estimating Streptomyces populations in soil. Soils are air-dried, 10g quantities are shaken in plastic bags containing 0.1% water agar and homogenized with a Stomacher homogenizer, serial dilutions are plated on a semi-selective culture (STR) medium and incubated for 2 weeks at 22°C, and the Streptomyces colonies are enumerated. Use of STR medium reduced the bacterial and fungal colonies recovered from soil to levels below that of the Streptomyces spp. while not affecting the number of Streptomyces colonies compared with those enumerated on yeast malt extract medium. A procedure for screening large numbers of Streptomyces strains for thaxtomin production, a phytotoxin recognized as a virulence marker in S. scabies, is also described. Strains are grown on oatmeal medium, and the thaxtomin is extracted from the medium by facilitated diffusion and detected by miniature thin layer chromatography. S. scabies and S. acidiscabies strains (approximately 130 from Ontario and 70 from other locations in North America) that produced thaxtomin did not form aerial mycelia or sporulate on STR medium within 2 weeks at 22°C. Ontario S. scabies strains that produced thaxtomin A also produced melanin on STR medium. All S. scabies strains from scab lesions that produced thaxtomin A had this colony morphology, whereas only 4 to 9% of strains from soil with this colony morphology produced thaxtomin A. Using these procedures, we determined that the population of thaxtomin-producing S. scabies in soil from a potato field in Ontario with a history of potato scab was about 20,000 CFU/g soil.

scholarly journals Isolation and Characterization of Plant-Pathogenic Streptomyces Species Associated with Common Scab-Infected Potato Tubers in Newfoundland

2016 ◽  
Vol 106 (2) ◽  
pp. 123-131 ◽  
Author(s):  
Joanna K. Fyans ◽  
Luke Bown ◽  
Dawn R. D. Bignell
Keyword(s):  
Common Scab ◽  
Virulence Gene ◽  
Potato Scab ◽  
Potato Tubers ◽  
Streptomyces Species ◽  
Genus Streptomyces ◽  
Thaxtomin A ◽  
Streptomyces Spp ◽  
Putative Virulence Gene ◽  
Isolation And Characterization

Potato common scab (CS) is an economically important crop disease that is caused by several members of the genus Streptomyces. In this study, we characterized the plant-pathogenic Streptomyces spp. associated with CS-infected potato tubers harvested in Newfoundland, Canada. A total of 17 pathogenic Streptomyces isolates were recovered from potato scab lesions, of which eight were determined to be most similar to the known CS pathogen S. europaeiscabiei. All eight S. europaeiscabiei isolates were found to produce the thaxtomin A phytotoxin and to harbor the nec1 virulence gene, and most also carry the putative virulence gene tomA. The remaining isolates appear to be novel pathogenic species that do not produce thaxtomin A, and only two of these isolates were determined to harbor the nec1 or tomA genes. Of the non-thaxtomin-producing isolates, strain 11-1-2 was shown to exhibit a severe pathogenic phenotype against different plant hosts and to produce a novel, secreted phytotoxic substance. This is the first report documenting the plant-pathogenic Streptomyces spp. associated with CS disease in Newfoundland. Furthermore, our findings provide further evidence that phytotoxins other than thaxtomin A may also contribute to the development of CS by Streptomyces spp.

scholarly journals Characterization of Streptomyces spp. Producing Indole-3-acetic acid as Biostimulant Agent

2015 ◽  
Vol 18 (2) ◽  
pp. 83 ◽  
Author(s):  
Charlie Ester De Fretes ◽  
Langkah Sembiring ◽  
Yekti Asih Purwestri
Keyword(s):  
Acetic Acid ◽  
Bacterial Culture ◽  
Cyperus Rotundus ◽  
Malt Extract ◽  
Streptomyces Sp ◽  
Iaa Production ◽  
Streptomyces Spp ◽  
Layer Chromatography ◽  
Indole 3 Acetic Acid

Twenty six isolates of Streptomyces spp. obtained from Cyperus rotundus L. rhizosphere were tested forability to produce indole-3-acetic acid (IAA) in yeast malt extract (YM) medium containing 2 mg/mL tryptophan.Screening of the isolates for ability to produce IAA was carried out by adding Salkowski reagent in bacteriaculture and was measured quantitatively by spectrophotometer at λ 530 nm. Thin Layer Chromatography (TLC)method was used to determine IAA. To ensure the IAA production in Streptomyces isolates, gene involved inIAA biosynthesis was detected by amplifying Tryptophan Monooxigenase (iaaM) gene. The study of the effectof tryptophan on the production of IAA was measured at different concentrations of tryptophan (0, 1, 2, 3,4, 5 mg/mL) in the bacterial culture. The result showed that there were two Streptomyces spp. isolates whichcould produce IAA, namely the isolates of Streptomyces sp. MS1 (125.48 μg/mL) and Streptomyces sp. BR27(104.13 μg/mL). The TLC result showed that the compound in both isolates was identifi ed to be IAA. Theamplifi cation results showed that iaaM gene was detected in both isolates. This results indicated that the IAMpathway is predicted involved in the biosynthesis of IAA in the selected isolates. Both of the isolates were ableto produce IAA after 24 h incubation and the highest production was at 120 h incubation with the concentrationof tryptophan was 2 mg/mL dan 1 mg/mL, respectively. Therefore, it is concluded that Streptomyces spp.isolates are able to produce IAA and potentially to be utilized as biostimulat agent. Keywords: Streptomyces spp., indole-3-acetic acid (IAA), indole-3-acetamide (IAM), Tryptophan Monooxigenasegene (iaaM)

Quantitative relationships among thaxtomin A production, potato scab severity, and fatty acid composition in Streptomyces

1998 ◽  
Vol 44 (8) ◽  
pp. 768-776 ◽  
Author(s):  
Linda L Kinkel ◽  
John H Bowers ◽  
Kyoko Shimizu ◽  
Eric C Neeno-Eckwall ◽  
Janet L Schottel
Keyword(s):  
Fatty Acid ◽  
Common Scab ◽  
Potato Scab ◽  
Quantitative Information ◽  
Fatty Acid Profiles ◽  
Field Isolates ◽  
Thaxtomin A ◽  
Streptomyces Spp ◽  
Potato Common Scab ◽  
Fatty Acid Data

Thaxtomin A production in culture, potato common scab severity (percentage of tuber surface infected or number of lesions per tuber), and fatty acid profiles were determined for 78 Streptomyces isolates. Only pathogenic Streptomyces spp. (n = 17) produced thaxtomin A in culture. Thaxtomin A production in culture (µg/mL) was significantly positively correlated with the percentage of tuber surface infected (R = 0.60; p = 0.017) but not with the number of lesions per tuber (R = 0.37; p = 0.17). An increase of 1 µg/mL in thaxtomin A production corresponded to an 11% increase in disease severity (percentage of tuber surface infected). The data indicate that quantitative information on the ability of a particular pathogen isolate or population to produce thaxtomin A may be critical to understanding and predicting the disease potential of that population. Using cluster analysis of fatty acid data, 94% of 67 unknown field isolates grouped with other field isolates having the same pathogenicity (plus or minus).Key words: thaxtomin A, phytotoxin, potato scab.

#37: Clinical Characterization of the Cases Relating to the Outbreak of Clostridioides difficile, in a Third-level Hospital in Mexico City: Diagnosis, Treatment, and Relay

2021 ◽  
Vol 10 (Supplement_1) ◽  
pp. S16-S16
Author(s):  
Ortiz Samuel ◽  
Martínez María Elena ◽  
Morayta Ramírez A
Keyword(s):  
Antibiotic Use ◽  
Clinical Findings ◽  
Prevention Measures ◽  
Clostridioides Difficile ◽  
Young Infants ◽  
Plastic Bags ◽  
History Of ◽  
Initial Episode ◽  
Group Sex ◽  
Healthcare Associated

Abstract Background Clostridioides difficile is an important cause of healthcare-associated infections. The epidemiology of C. difficile infection (CDI) in children has changed over the past few decades. There is now a higher incidence in hospitalized children, and there has been an emergence of community-onset infection. Neonates and young infants have high rates of colonization but rarely have symptoms. The well-known risk factor for CDI in children age 2 years or older is antibiotic use. Inflammatory bowel disease and cancer are associated with increased incidence and severity of CDI. Vancomycin or fidaxomicin is recommended for an initial episode of CDI. In environments where access to Vancomycin or Fidaxomycin is limited, it is suggested to use metronidazole for an initial episode of nonsevere CDI only. Methods A series of cases were carried out, in a study period from March to May 2018, total cases 8; the age group, sex, basic diagnosis, clinical findings, diagnostic method, and outcome in hospitalized patients in the Pediatric division of the “CMN 20 de Noviembre, ISSSTE” were described, where there is a total of 377 Sensitive beds, and 53 beds in the pediatric area of which 30 are not sensitive. Results We analyzed 8 cases of diarrhea with identification of C. difficile, in a period of 3 months, where there was a total of 148 admissions to the division of Pediatrics (100%) and presented a prevalence of 0.05% of the total income. Of those 8 cases reported, 37.5% were women and 62.5% men; The age fluctuated between 6 months and 18 years. All children had associated comorbidities. The frequency and type of comorbidities were Cancer 87.5% (Leukemias and Solid Tumors) and Neurological 12.5% ​​(Arterial Malformation and Neurological Sequelae). The main symptom that occurred was mucous diarrhea in 100% of patients, abdominal pain in 25% and evacuation with blood in 12.5% ​​of cases. All had a history of prior treatment with 100% broad-spectrum antibiotics, in a period of less than one month. All were treated with metronidazole (100%) and all presented clinical improvement, without complications; Similarly, all were diagnosed by PCR for toxin B (100%). The attributable risk of presenting Clostridioides disease in patients with Leukemia is 0.11. Conclusions Patients with Leukemia were the most affected during the C. difficile outbreak, of which 11 out of 100 of these patients are at risk of presenting C. difficile disease. The most important thing in these cases is prevention. Therefore, specific prevention measures were implemented to reduce the possibility of future outbreaks, such as handwashing with chlorexidine, contact isolation, handwashing every time there is contact with the patient, use of gloves when performing procedures, insulation of bedding in plastic bags and training of health personnel.

scholarly journals nec1, a Gene Conferring a Necrogenic Phenotype, Is Conserved in Plant-Pathogenic Streptomyces spp. and Linked to a Transposase Pseudogene

1998 ◽  
Vol 11 (10) ◽  
pp. 960-967 ◽  
Author(s):  
Raghida A. Bukhalid ◽  
Soo Young Chung ◽  
Rosemary Loria
Keyword(s):  
Restriction Fragment ◽  
Genetic Basis ◽  
Nucleotide Sequences ◽  
Pathogenic Species ◽  
Potato Tubers ◽  
Biosynthetic Genes ◽  
Oligonucleotide Primers ◽  
Thaxtomin A ◽  
Streptomyces Spp ◽  
Plant Pathogenicity

We are investigating the genetic basis for, and evolution of, plant pathogenicity in Streptomyces spp. The plant-pathogenic species S. scabies, S. acidiscabies, and S. turgidiscabies cause the scab disease of potato and produce the phytotoxins, thaxtomins. Forty-three Streptomyces strains representing the three species were evaluated; all thaxtomin A-producing Streptomyces strains were pathogenic on potato tubers and all but one hybridized to nec1 and ORFtnp, two genes previously cloned from S. scabies ATCC 41973. nec1 confers a pathogenic phenotype on S. lividans TK24, a nonpathogen, and ORFtnp is a transposase pseudogene located 5′ to nec1. The eight nonpathogenic strains tested neither produced thaxtomin A nor hybridized to nec1. ORFtnp and nec1 occurred on a single PvuII restriction fragment in all thaxtomin A-producing Streptomyces strains. The nucleotide sequences of the homologs of nec1 and ORFtnp from two pathogenic strains each of S. scabies, S. acidiscabies, and S. turgidiscabies were identical; oligonucleotide primers specific to this gene amplified homologs from all strains that hybridized to nec1. We propose that nec1 and ORFtnp have been horizontally mobilized from S. scabies to S. acidiscabies and S. turgidiscabies, and that nec1 is involved in pathogenicity and physically linked to the thaxtomin A biosynthetic genes.

Constituency Agents and British Party Politics

1975 ◽  
Vol 5 (4) ◽  
pp. 459-476 ◽  
Author(s):  
Robert Frasure ◽  
Allan Kornberg
Keyword(s):  
Party Politics ◽  
Office Work ◽  
Job Descriptions ◽  
Large Numbers ◽  
History Of ◽  
And Training

We began by reviewing the history of agency and by describing the two major parties' procedures for recruiting and training agents. Not surprisingly, the perceptions that agents have of their roles is not entirely congruent with official perceptions. Approximately 20 per cent of the agents of both parties felt that the performance of various representational functions was the most important part of their job although these tasks are not included in official job descriptions. Moreover, although a majority of the agents in each party believed that their most important job was to build and maintain constituency organizations capable of winning elections, the majority of their time was not spent on this task. Conservative agents seemingly spent a disproportionate amount of time doing routine office work, whereas over 40 per cent of the Labour agents spent much of their time trying to raise the funds that paid their salaries. Large numbers of agents in both parties agreed that raising money in their constituencies was a difficult and largely unrewarding task.

“Only intelligent attendants need apply”: the history of Western Australia’s first asylum at Fremantle (1865–1909)

2021 ◽  
pp. 103985622110142
Author(s):  
Phil Maude
Keyword(s):  
Primary Sources ◽  
Work Roles ◽  
Large Numbers ◽  
Convict Transportation ◽  
History Of

Objective: To examine the history of Fremantle, Western Australia’s first purpose-built asylum. Method: A range of primary sources were consulted. Results: Fremantle was opened in 1865 to house inmates away from the populace and for the most part under the care of Dr HC Barnett. Attendants as well as inmates were occupied with work roles that kept the asylum functioning cost effectively. Conclusion: Within 15 years, the structure was neglected and overcrowded. Changes to the Penal Servitude Act limiting convict transportation, petty crime and a need to manage its proliferation resulted in large numbers of people being incarcerated at Fremantle.

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