摘要:

By strictly defining the procedure for handling and storing the electrodes, contamination was limited to microorganisms from the air. For the purpose of this investigation, therefore, sterilization is defined as the complete inactivation or killing of air-borne bacteria, yeasts, and molds. If the organisms are not present in such a way as to offer mutual protection from the radiation, the total energy at 2537 Å necessary to inactivate the most resistant organism may be assumed to ensure sterilization.Aspergillus nigerv. Tiegh. was identified as the most resistant contaminant, and electrostatic sampling showed that clumps containing up to about 40 spores ofA.nigerStrain 6277 became air-borne. These clumps required approximately 60,000 μw. min. per cm.2at 2537 Å for inactivation. Used with the accessory procedures, exposure to 680 μw. per cm.2for two hours was found to provide a safe margin and to ensure sterilization of carefully cleaned and specially mounted electrodes. A satisfactory design for a crevice-free glass electrode sterilizable by ultraviolet light is described. E.m.f. changes in glass–calomel cells sterilized by the recommended procedure do not exceed 0.4 mv., corresponding to 0.006 pH units.

ISSN:1923-4287    

DOI:10.1139/cjr50c-009

出版商:NRC Research Press    

年代:1950

数据来源: NRC

摘要:

Growth ofRhizobium, as measured by turbidity of cultures, was not inhibited appreciably by the brown, fluorescent products formed by the reaction of various amino acids with dextrose. Autoclaving the medium with dextrose actually improved growth of the organism in some trials by partially destroying an amino acid that was inhibitory if present in excess.

ISSN:1923-4287    

DOI:10.1139/cjr50c-010

出版商:NRC Research Press    

年代:1950

数据来源: NRC

摘要:

The acid soluble phosphorus fraction of cells ofPseudomonas aeruginosaharvested from a glucose medium was found to consist mainly of difficultly hydrolyzable compounds. None of the fractions contained reducing compounds even after 12 hr. hydrolysis with normal hydrochloric acid nor could fructose be detected. It could therefore be concluded that glucose-1-phosphate, glucose-6-phosphate, fructose-6-phosphate, and hexose diphosphate were absent. Analysis of a glucose solution that had been metabolized by cells of this organism under conditions of fluoride inhibition confirmed the analysis of the cellular material. The lack of normal intermediates of the Embden–Meyerhof scheme is discussed in relation to the gluconic acid, 2-ketogluconic acid pathway of glucose oxidation.

ISSN:1923-4287    

DOI:10.1139/cjr50c-011

出版商:NRC Research Press    

年代:1950

数据来源: NRC

摘要:

A program of screening a wide range of fungi for ability to "ferment" glucose and various agricultural wastes and surpluses in submerged culture revealed that species ofUstilagowere capable of rapid dissimilation of carbohydrates with the production of (1) a complex substance appearing as long needlelike optically active crystals in the culture mixture, (2) fats and sterols, and (3) a range of new antibiotic substances designated as Ustizeain A, B, etc. The yields of (1) and (2) are closely related and together they constitute the major portion of the by-products of metabolism of the smut. The antibiotics (3) are stable and effectivein vitroagainst Gram-positive bacteria such asBacillus subtilisandMycobacterium smegmatis; against Gram-negativeBrucella bronchiseptica; and against many fungi including species ofAspergillus nigerandA.flavusgroups, certain penicillia,Verticillium, and many other Fungi Imperfecti.

ISSN:1923-4287    

DOI:10.1139/cjr50c-012

出版商:NRC Research Press    

年代:1950

数据来源: NRC