Fermentation organisms : a laboratory handbook / by Alb. Klöcker; translated from the german by G. E. Allan and J. H. Millar.

Date:
1903
Catalogue details

Licence: In copyright

Credit: Fermentation organisms : a laboratory handbook / by Alb. Klöcker; translated from the german by G. E. Allan and J. H. Millar. Source: Wellcome Collection.

Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.

    123/458 (page 99)
    Suppression of Bacteria in Yeast Growths.—If it is required to encourage the development of a bacteria- infected culture of an alcoholic yeast, the method usually adopted is to cultivate the impure growth in an acid nutrient medium. Nearly all bacteria are killed in this way, or are to a great extent hindered in tlieir development, so that the alcoholic yeasts in the mixture preponderate. But it is not always possible to use sucli an acid medium, as the organism to be cultivated may also be influenced adversely. In such a case the cultures can be exposed to the action of light, as bacteria can withstand the action of light only to a small degree. This was proved several years ago by Downes and Blunt. Experiments in this <lirection have also been made at the Carlsberg laboratory, and have shown that spore cultures of saccharomycetes on gypsum blocks can be kept free from bacteria if exposed to light. 3.—Preparation of Pure Cultures. The methods for preparing pure cultures described in the following pages are only those of practical importance and application. Pure Cultures for Investigations in Morphology AND Development.—The preparation of pure cultures for investigating morphology and development was begun very early, the development of the single cell being observed under the microscope. This was perhaps first done by Ehrenberg (1821) ; later, Mitscherlich studied the budding of the yeast cell in the same manner. The process of microscopical examination as a means of studying morphology and development was largely employed in investigating fungi belonging to the most widely separated divisions of the system. The technique was brought to a high degree of perfection, especially by Brefeld (1875). 7 *