Malt Extract HiVeg™ Broth Base

Principle And Interpretation

The laboratory diagnosis of fungal infection relies largely on direct as opposed to indirect methods. Diagnosis is almost always based upon the mycological laboratory investigation. Considerable importance should be placed upon direct microscopy in addition to isolation of the organisms. Media used for the isolation of fungi are acidic and are designed to be inhibitory to bacteria. The use of malt and malt extracts for the propagation of yeasts and moulds is quite common Reddish (1) described a culture medium prepared from malt extract that was a satisfactory substitute for wort. Malt Extract Medium is similar to the formula of Galloway and Burgess (2) used for the detection, isolation and enumeration of yeasts and moulds. Malt Extract Broth is recommended for the examination of yeasts and moulds in the U.S. Food and Drug Administrations Bacteriological Analytical Manual (2). For mycological counts it may be desirable to prepare more acidic medium in order to suppress bacterial growth. Malt Extract HiVeg™ Broth Base is prepared by using vegetable peptones in place of animal based peptones which make the media free of BSE/TSE risks. Malt extract provides an acidic environment and nutrients favourable for growth and metabolism of yeasts and moulds. HiVeg™ peptone No. 4 rapidly gives a luxuriant growth with typical morphology and pigmentation. For mycological count, it is advisable to adjust the reaction of medium more acidic with addition of 10% lactic acid. Antibiotics may be added as sterile solutions to the molten medium immediately before dispensing into sterile tubes (5) in order to suppress bacterial growth. Malt Extract HiVeg™ Broth Base has been widely used in the maintenance, isolation and identification of fungi and it is also proposed in several pharmacopeias as a medium for the control of sterility in pharmaceutical products, though it is mostly used for comparative morphological studies.