A “Loop” Method for Counting Viable Bacteria or Bacteriophage

Asheshov, Igor N.; Heagy, F. C.

doi:10.1139/cjms51-001

Cited by 9 publications

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“…The "loop" dilution method of Asheshov and Heagy (4) was used in all experiments for diluting and plating to count both phage particles and bacterial cells. This method gave a standard error of measurement of 4 per cent.…”

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confidence: 99%

A Study of the Action of Phagolessin A58 on the T Phages

Hall

Asheshov

1953

Journal of General Physiology

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Phagolessin A58, an antibiotic produced by an unidentified strain of Streptomycetes sp. was described in a previous publication (1). The antibiotic is not yet available in crystalline form and the most active fractions contain considerable amounts of impurities. Despite this, the antibiotic was considered sufficiently interesting to justify a more detailed study of its antiphage properties.Phagolessin A58 is moderately active against a number of gram-positive and gram-negative bacteria, and against a wide range of bacterial viruses. Out of 60 viruses examined, 50 proved to be sensitive to a greater or lesser degree. The antiphage action is of the direct phagicidal type, the antibiotic causing an apparently irreversible inactivation of free phage particles after a relatively short contact. This inactivation of phage particles by phagolessin A58 is inhibited by desoxyribose nucleic acid, and to a lesser extent by ribose nucleic acid.The phages included in this present study comprise the seven coli-phages of the T system (2), acting on their common host Escherichia coli strain B. The authors are indebted to Dr. Max Delbriick who supplied the phages and their host strain. The r mutants (3) of phages T4 and T6 were used in place of the wild types. Materials and MethodsPhagolessin ASg.--Extracts of the antibiotic used in this work were methyl alcohol solutions of lyophilized material and contained variable amounts of impurities. Concentrations were expressed in units per milliliter. A solution having an antiphage activity at a dilution of 1:40,000 against cholera phage C, the standard phage for this antibiotic, was considered to contain 40,000 units per ml. Weekly serial dilutions were run against the standard phage in order to detect any loss in antiphage activity in the preparation in current use. Since this antibiotic is highly unstable at neutral or alkaline reaction, dilutions of the active material into neutral medium were made immediately before being used in experiments.Med/a.--The nutrient broth used in all experiments contained 0.8 per cent Dffco nutrient broth and 0.5 per cent sodium chloride. Agar plates were prepared by adding Difco bacto agar to the nutrient broth, 2.0 per cent agar being used to plate phages T1, T3, and T7, and 1.2 per cent agar for phages T2, T4r, T5, and T6r. This procedure made clearing counts considerably easier.

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confidence: 99%

A Study of the Action of Phagolessin A58 on the T Phages

Hall

Asheshov

1953

Journal of General Physiology

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“…Cette préincubation est réalisée dans un milieu Identique à celui dans lequel la mesure de l'activité de l'antibiotique sera faite (4). Un prélèvement de 0,01 ml est effectué d'heure en heure dans le tube ensemencé contenant l'antibiotique (4), pas sé sur filtre Mllllpore et lavé à l'aide du bouillon (5). Le filtre Mllllpore, retiré de l'appareil, est appliqué à la surface d'une gé lose nutritive (6), Les boites de Pétri ainsi préparées, sont Incu bées à 37» pendant 1, 2 et 3 jours.…”

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Cinetique De L'action Des Antibiotiques En Milieu Plasmatique

Yourassowsky

1967

Acta Clinica Belgica

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Thèse de doctorat/ PhD ThesisCitation APA: Yourassowsky, E. (1967 Cette thèse de doctorat a été numérisée par l'Université libre de Bruxelles. L'auteur qui s'opposerait à sa mise en ligne dans DI-fusion est invité à prendre contact avec l'Université (di-fusion@ulb.ac.be).Dans le cas où une version électronique native de la thèse existe, l'Université ne peut garantir que la présente version numérisée soit identique à la version électronique native, ni qu'elle soit la version officielle définitive de la thèse.DI-fusion, le Dépôt Institutionnel de l'Université libre de Bruxelles, recueille la production scientifique de l'Université, mise à disposition en libre accès autant que possible. Les oeuvres accessibles dans DI-fusion sont protégées par la législation belge relative aux droits d'auteur et aux droits voisins. Toute personne peut, sans avoir à demander l'autorisation de l'auteur ou de l'ayant-droit, à des fins d'usage privé ou à des fins d'illustration de l'enseignement ou de recherche scientifique, dans la mesure justifiée par le but non lucratif poursuivi, lire, télécharger ou reproduire sur papier ou sur tout autre support, les articles ou des fragments d'autres oeuvres, disponibles dans DI-fusion, pour autant que :Le nom des auteurs, le titre et la référence bibliographique complète soient cités; L'identifiant unique attribué aux métadonnées dans DI-fusion (permalink) soit indiqué;Le contenu ne soit pas modifié.

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“…After a few hours the "mixed liquor"-wastes + solids -is run into artificial lagoons where the sludge settles. The supernatant meets legal standards for discharge of effluents into rivers and seas (4,5 ) . Some settled sludge is returned to the aeration tanks to see incoming wastes.…”

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confidence: 93%

Fluctuations in Populations of 3 Vorticella Species from an Activated‐Sludge Sewage Plant

Reid¹

1969

The Journal of Protozoology

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SYNOPSIS. To evaluate Vorticella populations in an activated sludge sewage‐disposal plant as a) indicators and b) contributors to purification, population behavior in the plant was compared with behavior in clonaI cultures maintained with mixed sludge microflora. In a 12‐month survey of protozoa in the plant, of 37 spp recorded only 9—all ciliates—were indigenous. Ciliate populations fluctuated cyclically. Alternations in dominance of Vorticella convallaria (L.) with V. octava (Stokes) +V. aequitata (Kahl) apparently followed changes in bacterial activity as indicated by changes in reduction of biochemical oxygen demand and suspended solids of the wastes. This correlation of Vorticella and bacterial activities was also investigated with clonal populations of the vorticellas and their accompanying mixed microflora—the bacteria being isolated together with the vorticellas from sludge samples. The mixed microflora which consistently supported healthy vorticellas was predominantly proteolytic. Varying periods of dominance in Vorticella species thus indicated activity of their supporting microflora. Log‐phase bacteria activity stimulated V. octava; stationary and declining phases stimulated V. convallaria. Thus, V. octava appeared predatory and V. convallaria appeared to require bacterial conditioning of the medium. Bacterial activity was stimulated by V. octava predation. Vorticella activity may thus promote purification.

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A “Loop” Method for Counting Viable Bacteria or Bacteriophage

Cited by 9 publications

References 0 publications

A Study of the Action of Phagolessin A58 on the T Phages

A Study of the Action of Phagolessin A58 on the T Phages

Cinetique De L'action Des Antibiotiques En Milieu Plasmatique

Fluctuations in Populations of 3 Vorticella Species from an Activated‐Sludge Sewage Plant

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