An introduction to bacteriological and enzyme chemistry / [Gilbert John Fowler].

  • Fowler, Gilbert J. (Gilbert John), 1868-
Date:
[1911]
Catalogue details

Licence: In copyright

Credit: An introduction to bacteriological and enzyme chemistry / [Gilbert John Fowler]. Source: Wellcome Collection.

    32/350 (page 22)
    sterilised by exposure to moist steam for about twenty minutes, especially if tbe operation is repeated in forty-eight hours. In this way any spores which are specially resistant to sterilisa- tion, and which may have escaped the first heating, will have had time to develop, and the adult organism will be killed by the second heating. For sterilising media or apparatus in this manner, a very simple form of steriliser will suffice, which is illustrated in Fig. 4 a. It consists of a large semicircular tin can, with ordinary cover, and provided with a perforated false bottom of tin plate about an inch from the bottom of the can. About half-an-inch in depth of water is placed in the bottom of the can, which can be quickly boiled by the flame of a Bunsen burner beneath, the whole can being thus filled with moist steam. Culture Media for Bacteria Broth or houillon.—The basis of most media, suitable for cultivating bacteria, is broth or ‘ bouillon. This is made by boiling up one pound of finely minced lean beef free from fat or gristle with one litre of water in a large flask and strain- ing through muslin; five grammes of salt (sodium chloride) and ten grammes of peptone are added, and the mixture boiled for five minutes. The liquid is rendered very faintly alkaline with carbonate of soda, made up to a litre if necessary with fresh water, the neck of the flask plugged with cotton wool, and the whole sterilised. Nutrient gelatine is made by dissolving 100 grammes (or 150 grammes if a rather high melting-point is required) of gelatine in 1000 c.c. of broth. The gelatine should be first soaked in water to render it easily soluble and the whole volume of gelatine broth made up to 1100 c.c. If necessary, the solution after addition of the gelatine can be clarified by warming on the water bath with the white of one egg. The whole is then filtered through a pleated filter paper in a hot