scholarly journals Behaviour of Diphtheria Bacilli in Acidified Media, especially with reference to Virulence Tests

1922 ◽  
Vol 21 (2) ◽  
pp. 155-167 ◽  
Author(s):  
I. Walker Hall
Keyword(s):  
Nitric Acid ◽  
Culture Media ◽  
Artificial Culture ◽  
Fermentation Products ◽  
Time Required ◽  
Peptone Medium ◽  
Lactic Acids ◽  
Harmful Effects ◽  
Extended Trial ◽  
Peptone Broth

1. The growth of diphtheria bacilli in suger-free pure casein digest broth may be accelerated by the addition of dilute nitric, acetic and lactic acids, and delayed by certain monobasic fatty acids.2. The limiting acid zone for toxic and non-toxic varieties is unaffected by initial dilute acidifications by several acids, but incresaed by the addition of citric acid.3. The time periods and intensity of the reaction changes produced by diphtheria bacilli growing in a sugar-free casein digest medium are altered by the addition of certain acids. Toxic strains produce earlier and more progressive alkalinity when dilute acetic or nitric acid is included in the medium: and later and lessened alkalinity in the presence of butyric, formic, and propionic acids. Certain other typical acids do not exert any obvious action. Non-toxic strains are less affected by the selected acids, although butyric acid generally retards reaction changes.4. The time required for virulence testing is decreased, and the potency of the bacillus under examination is more evident when 1/200 η acetic or nitric acid is added to the culture medium. Acidified casein digest plus peptone broth yields practically the same results as acidified fermented veal peptone infusion. The acidification does not affect the metabolism of non-toxic strains.5. The disadvantages of unfermented meat infusions and the ascribed harmful effects of the fermentation products in fermented meat broths, may perhaps be avoided by the substitution of casein digest peptone medium. The advantages of the starting action of the glucose may be retained by adding acetic or nitric acid to the casein digest.6. Individual strains of diphtheria bacilli differ considerably in their capacity of altering the reaction of culture media, and in their toxic potency. It does not seem permissible to apply to newly isolated organisms all the published results obtained from cultures that have been repeatedly subcultured and established as toxin producers in nutrient bouillon. As a presumptive test in the virulence testing of bacilli just transferred from human tissues to artificial culture media the tendency of non-toxic strains to produce early formation of alkali in adequately buffered and adjusted unfermented veal broth may be thought worthy of extended trial.

Performance of Different Solid and Liquid Culture Media for the Improvement of Tuberculin Production

2020 ◽  
Keyword(s):  
Culture Media ◽  
Synthetic Medium ◽  
Chemical Properties ◽  
Economic Loss ◽  
Delayed Type Hypersensitivity ◽  
Basic Medium ◽  
Primary Methods ◽  
Lowenstein Jensen ◽  
Time Required ◽  
Modified Media

Tuberculosis (TB) is one of the most important zoonotic bacterial diseases. A huge economic loss which could be direct or indirect are associated with the disease. Currently, the primary methods used for detection of TB in humans and cattle include the measurement of a delayed type hypersensitivity to purified protein derivative (PPD). So, the need for preparation of purified PPD with adequate properties and increasing the final PPD yield with decreasing the time of tuberculin production has stimulated the interest in the development of its preparation. Our study was performed to compare between the standard and modified media for improving tuberculin production. Middle brook 7H10 agar medium was used as a modified basic medium for mycobacterial growth, followed by cultivation of mycobacteria on Middle brook 7H9 broth medium. For the production, strains were inoculated onto the culture medium (Dorest Henly synthetic medium). Other steps for tuberculin production was done according to standard Weighbridge protocol. The results demonstrated that the using of both Middle brook 7H10 agar and Middle brook 7H9 broth instead of Lowenstein-Jensen (LJ) and glycerin broth media which used in currently produced tuberculin, have better physical and chemical properties. In addition, reducing the time required for production by accelerating the time of microbial growth. Also, it was found that the tuberculin produced using modified media was slightly more potent or the same as currently tuberculin produced. So, both Middle brook 7H10 agar and Middle brook 7H9 broth media are recommended for production of tuberculin saving time and increasing potency of the product but more investigation was recommended for estimation types of protein present in both locally prepared and modified tuberculin.

scholarly journals Microbial Community Dynamics during Production of the Mexican Fermented Maize Dough Pozol

2000 ◽  
Vol 66 (9) ◽  
pp. 3664-3673 ◽  
Author(s):  
Nabil ben Omar ◽  
Fr�d�ric Ampe
Keyword(s):  
Lactic Acid ◽  
Microbial Community ◽  
Community Dynamics ◽  
Denaturing Gradient Gel Electrophoresis ◽  
Culture Media ◽  
Polyphasic Approach ◽  
Close Relative ◽  
Fermented Foods ◽  
Fermentation Products ◽  
Rdna Genes

ABSTRACT The dynamics of the microbial community responsible for the traditional fermentation of maize in the production of Mexican pozol was investigated by using a polyphasic approach combining (i) microbial enumerations with culture media, (ii) denaturing gradient gel electrophoresis (DGGE) fingerprinting of total community DNA with bacterial and eukaryotic primers and sequencing of partial 16S ribosomal DNA (rDNA) genes, (iii) quantification of rRNAs from dominant microbial taxa by using phylogenetic oligonucleotide probes, and (iv) analysis of sugars and fermentation products. AStreptococcus species dominated the fermentation and accounted for between 25 and 75% of the total flora throughout the process. Results also showed that the initial epiphytic aerobic microflora was replaced in the first 2 days by heterofermentative lactic acid bacteria (LAB), including a close relative ofLactobacillus fermentum, producing lactic acid and ethanol; this heterolactic flora was then progressively replaced by homofermentative LAB (mainly close relatives of L. plantarum, L. casei, and L. delbrueckii) which continued acidification of the maize dough. At the same time, a very diverse community of yeasts and fungi developed, mainly at the periphery of the dough. The analysis of the DGGE patterns obtained with bacterial and eukaryotic primers targeting the 16S and 18S rDNA genes clearly demonstrated that there was a major shift in the community structure after 24 h and that high biodiversity—according to the Shannon-Weaver index—was maintained throughout the process. These results proved that a relatively high number of species, at least six to eight, are needed to perform this traditional lactic acid fermentation. The presence ofBifidobacterium, Enterococcus, and enterobacteria suggests a fecal origin of some important pozol microorganisms. Overall, the results obtained with different culture-dependent or -independent techniques clearly confirmed the importance of developing a polyphasic approach to study the ecology of fermented foods.

scholarly journals Effects of Temperature and pH on Fusarium oxysporum and Soybean Seedling Disease

Plant Disease ◽  
2019 ◽  
Vol 103 (12) ◽  
pp. 3234-3243
Author(s):  
David R. Cruz ◽  
Leonor F. S. Leandro ◽  
Gary P. Munkvold
Keyword(s):  
Fusarium Oxysporum ◽  
Root Rot ◽  
Radial Growth ◽  
Culture Media ◽  
Fungal Growth ◽  
Artificial Culture ◽  
Vitro Assay ◽  
Seedling Disease ◽  
Soybean Seedlings

Fusarium oxysporum (Fo) is an important pathogen that reduces soybean yield by causing seedling disease and root rot. This study assessed the effects of pH and temperature on Fo fungal growth and seedling disease. In an in vitro assay, 14 Fo isolates collected from symptomatic soybean roots across Iowa in 2007 were grown on artificial culture media at five pH levels (4, 5, 6, 7, and 8) and incubated at four temperatures (15, 20, 25, or 30°C). In a rolled-towel assay, soybean seeds from Fo-susceptible cultivar Jack were inoculated with a suspension of a pathogenic or a nonpathogenic Fo isolate; both isolates were previously designated for their relative aggressiveness in causing root rot at 25°C. The seeds were placed in rolled germination paper, and the rolls were incubated in all combinations of buffer solutions at four pH levels (4, 5, 6, and 7), and four temperatures (15, 20, 25, or 30°C). There was a significant interaction between temperature and pH (P < 0.05) for in vitro radial growth and root rot severity. Isolates showed the most in vitro radial growth after incubation at pH 6 and 25°C. For the rolled-towel assay, the pathogenic isolate caused the most severe root rot at pH 6 and 30°C. Gaussian regression analysis estimates for optimal conditions were pH 6.3 at 27.1°C for maximal fungal growth and pH 5.9 at 30°C for maximal root rot severity. These results indicate that optimal pH and temperature conditions are similar for Fo growth and disease in soybean seedlings and suggest that Fo may be a more important seedling pathogen when soybeans are planted under warm conditions in moderately acidic soils.

scholarly journals Comparative evaluation of three different commercial blood culture media for recovery of anaerobic organisms

1977 ◽  
Vol 5 (5) ◽  
pp. 505-509
Author(s):  
J I Mangels ◽  
L H Lindberg ◽  
K L Vosti
Keyword(s):  
Blood Culture ◽  
Comparative Evaluation ◽  
Culture Media ◽  
Anaerobic Bacteria ◽  
Brain Heart Infusion ◽  
Blood Stream ◽  
Becton Dickinson ◽  
Commercial Media ◽  
The Brain ◽  
Peptone Broth

A comparison of three different commercial media was made to assess their recovery of anaerobic organisms from the blood stream. The three media used were the 50-ml brain heart infusion broth with added CO2 (Pfizer), the 50-ml Thiol broth with added CO2 (Difco), and the 50-ml prereduced, supplemented peptone broth in a Vacutainer tube with added CO2 (Becton-Dickinson). During a period of 17 consecutive months, 12,216 specimens of blood were processed with each broth. Aerobic or anaerobic bacteria were recovered from 913 specimens (7%). Seventy-four specimens (8%) of the total positive cultures contained anaerobic organisms. When potential contaminants were removed from the totals, 7% of the positive cultures contained anaerobic organisms and 7% of the patients with positive cultures had bacteremia with anaerobic bacteria. Of the three commercial blood culture media studied, the prereduced, supplemented peptone broth recovered more anaerobic organisms than did either the brain heart infusion or Thiol broths.

scholarly journals Dimorphism in Neopseudocercosporella capsellae, an Emerging Pathogen Causing White Leaf Spot Disease of Brassicas

2021 ◽  
Vol 11 ◽  
Author(s):  
Niroshini Gunasinghe ◽  
Martin J. Barbetti ◽  
Ming Pei You ◽  
Prabuddha Dehigaspitiya ◽  
Stephen Neate
Keyword(s):  
Leaf Spot ◽  
Culture Media ◽  
Control Measures ◽  
Effective Control ◽  
Leaf Spot Disease ◽  
In Planta ◽  
Artificial Culture ◽  
White Leaf ◽  
Yeast Phase

White leaf spot pathogen: Neopseudocercosporella capsellae causes significant damage to many economically important Brassicaceae crops, including oilseed rape through foliar, stem, and pod lesions under cool and wet conditions. A lack of information on critical aspects of the pathogen’s life cycle limits the development of effective control measures. The presence of single-celled spores along with multi-celled conidia on cotyledons inoculated with multi-celled conidia suggested that the multi-celled conidia were able to form single-celled spores on the host surface. This study was designed to demonstrate N. capsellae morphological plasticity, which allows the shift between a yeast-like single-celled phase and the multi-celled hyphal phase. Separate experiments were designed to illustrate the pathogen’s morphological transformation to single-celled yeast phase from multi-celled hyphae or multi-celled macroconidia in-vitro and in-planta. Results confirmed the ability of N. capsellae to switch between two morphologies (septate hyphae and single-celled yeast phase) on a range of artificial culture media (in-vitro) or in-planta on the host surface before infection occurs. The hyphae-to-yeast transformation occurred through the production of two morphologically distinguishable blastospore (blastoconidia) types (meso-blastospores and micro-blastospores), and arthrospores (arthroconidia).

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