Ministry of Supply

About: Ministry of Supply is a based out in . It is known for research contribution in the topics: Polarography & Bacillus (shape). The organization has 416 authors who have published 355 publications receiving 8951 citations. The organization is also known as: MoS.

Infra-Red Spectroscopy and its Application to Microbiology.

Abstract: Colorimeters and non-recording spectrophotometers for visible and ultra-violet light have been used for many years and are to be found in most microbiological laboratories. With the need for greater speed of operation, recording instruments are now coming into more general use. During the last two decades recording infra-red spectrophotometers have been developed and these have enabled the absorption measurements on micro-organisms to be extended into the infra-red region of the spectrum. Two factors have tended to retard the use of infra-red spectrophotometry. One is the high initial cost of the equipment and the other is the large absorption of infra-red radiation by water. Despite these difficulties, a considerable amount of work has now been done and it seems profitable to review the varied applications to which infra-red spectroscopy has already been put and to indicate the results which have been obtained by its use.

Adenosine deaminase and ribosidase in spores of Bacillus cereus.

Abstract: Inosine is a more effective germination stimulant than adenosine for spores of Bacillus cereus and B. anthracis (Powell & Hunter, 1955). A crude method of assessment, based on the paper-ionophoresis technique of Wade & Morgan (1954), indicated that extracts from disintegrated resting spores of B. cereus converted adenosine into inosine. This suggested the possibility that inosine might be, in fact, the germination stimulant, and that germination of a given spore suspension in adenosine might depend, to some extent, on its adenosine-deaminase activity. We have now studied quantitatively the deamination of adenosine by resting and germinated spores of B. cereus, and also its further breakdown to the purine and free ribose. The possible relationships between these reactions and spore germination in B. cereus are discussed. Part of this work has already been briefly reported (Powell, 1955). 40 mm sodium potassium phosphate buffer pH 7-3. Resting and germinated spores were disintegrated in suspensions containing 2 x 1010 spores/ml., using the Mickle (1948) tissue disintegrator with Ballotini beads size 12. The suspensions were ice-cooled at 10 min. intervals during disintegration, which usually took 1 hr. Homogenates were separated by centrifuging for 30 min. at 6000 g to give extract and 'debris' preparations. For some experiments (see below) the deaminase was precipitated from extracts with 30% (v/v) ethanol at 0°. It redissolved readily in water and buffer solutions. A spore-coat preparation was obtained by disintegrating a resting-spore suspension for approximately 20 min., i.e. until the appearance of stained films indicated that disruption had occurred, but the suspension still consisted mainly of recognizable spore-coat fragments. Smaller particles of doubtful origin were removed by repeatedly suspending in

The composition of the spore coats of Bacillus megatherium, B. subtilis and B. cereus.

Abstract: A peptide containing glutamic acid, alanine, aediaminopimelic acid and hexosamine was found to be present in exudates from germinating spores and in extracts from disintegrated resting spores (Powell & Strange, 1953; Strange & Powell, 1954). It was suggested that the peptide might be derived from the spore coat when this underwent a change in permeability during germination or was damaged mechanically. In the present study of the chemical composition of spore coats, these were obtained by mechanical disintegration, a method which has been used by a number of workers to obtain bacterial cell walls (Salton & Home, 1951; Salton, 1953; Cunmmins, 1954). There seemed little hope of demonstrating the presence of the peptide in the coat of the resting spore by this method, as the peptide appeared to be so readily freed during disintegration. It was found, however, that sporecoat preparations of BaciUus mnegatherium still contained considerable amounts, and B. subtilis smaller amounts, of bound hexosamine which was slowly released in the form of the peptide previously isolated. This process and the effect of various enzymes on it are described. A similarity was found between the effect of lysozyme on spore peptide and lysozyme substrate, which is a mucopolysaccharide considered to exist within certain bacterial cell walls as an insoluble complex (Meyer, Palmer, Thompson & Khorazo, 1936; Epstein & Chain, 1940; Meyer & Hahnel, 1946; Salton, 1952), and this is also described.