292 DIFCO MANUAL 



per cent added to a carbohydrate-free medium causes a definite increase in the 

 rate of growth of many microorganisms. 



BACTO-LAGTOSE (B156) 



Bacto-Lactose is a highly purified disaccharide, recommended for use in the 

 study of the fermentation reactions of bacteria. It is free from dextrose as deter- 

 mined by culture of Salmonella typhosa and controlled by determinations of 

 changes in hydrogen ion concentration. It contains no trace of casein or other 

 proteins, starch, alcohol or heavy metals. Its specific rotation is +52.4 with 

 0.5° tolerance. 



Lactose media are of distinct value for the presumptive test for coliform 

 bacteria in water and milk. Many of the differential media used for identifica- 

 tion of organisms of the colon-typhoid-dysentery group also contain this carbo- 

 hydrate either alone or in combination with other fermentable substances. In 

 fluid media, lactose is usually employed in a concentration of 0.5 per cent, but 

 in solid media higher concentrations may be used. 



ADDITIONAL COMPOUNDS 



In addition to the above we also prepare the following purified carbohydrates, 

 polyhydric alcohols, glucosides and salts of organic acids. These are especially 

 suited for bacteriological culture media. 



Adonitol (Adonite) (B157) Invert Sugar Syrup (B166) Rhamnose (Isodulcitol) 



Aesculin (B158) Lactose (see Bacto-Lactose) (B175) 



/-Arabinose (B159) (B156) Saccharose (Sucrose) (B176) 



Cellobiose (Bi6q) Levulose (J-Fructose, from Salicin (B177) 



Dextrin (B161) Inulin) (B167) Soluble Starch (B178) 



Dextrose (<f -Glucose, see Maltose (B168) Sodium Hippurate (B330) 



Bacto-Dextrose) (B155) Maltose, Technical (B169) ^/-Sorbitol (Sorbite) 



Dulcitol (Dulcite) (B132) ^-Mannitol (Mannite) CB170) (B179) 



J-Galactose (B163) J-Mannose (B171) Trehalose (UiBoJ 



Glycerol (B282) Melezitose (B172) ^/-Xylose (B181) 



t-Inositol (B164) Melibiose (B173) 



Inulin (B165) Raffinose (B174) 



CARBOHYDRATE SOLUTIONS IN AMPULS 



Carbohydrate solutions, sterilized by filtration, are prepared for the use of 

 laboratories desiring fermentation media in which the carbohydrate has not been 

 heat sterilized. These carbohydrates are ampuled in 10 ml. amounts, each ampul 

 containing 1 gram of the carbohydrate in sterile solution. Carbohydrate solutions 

 in ampuls are convenient and economical when small quantities of fermentation 

 media are required. 



For the preparation of carbohydrate media, the basic sugar-free medium is 

 prepared and sterilized as usual. The desired carbohydrate solution is then added 

 aseptically and the medium is dispensed into sterile containers with aseptic pre- 

 cautions. To prepare a medium containing one per cent of the carbohydrate the 

 contents of one ampul are added to 90 ml. of medium; to prepare a medium 

 with 0.5 per cent of the carbohydrate, the contents of one ampul are added to 

 190 ml. of the sterile sugar-free base. The final medium should always be incu- 

 bated before use to insure its sterility. 



In conjunction with these solutions reference should be made to Bacto- 



