796 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Table 1.2.1. Conditions for maintenance of test organisms Genus Bacillus Clostridium Citrobacter Enterobacter Escherichia Klebsiella Proteus Pseudomonas Salmonella Staphylococcus Streptococcus Medium Nutrient Agar Cooked meat* Nutrient Agar Nutrient Agar Nutrient Agar Nutrient Agar Nutrient Agar Peptone Water Agar Dorset egg* Nutrient Agar Cooked Meat Incubation Temper- Time ature 30 ø 48h 37 ø 48h 37 ø 18h 37 ø 18h 37 ø 18h 37 ø 18h 37 ø 18h 30 ø 18h 37 ø 18h 37 ø 18h 37 ø 18h Storage 5-10 ø 5-10 ø 5-10 ø 5-10 ø 5-10 ø 5-10 ø 5-10 ø 5-10 ø 5-10 ø 5-10 ø 5-10 ø Interval between sub-cultures (months) 6-12 6-12 3-6 6 6 3 3 3 6-12 3 3 *Obtainable as a ready prepared culture medium from Oxoid Ltd. 1.3 Fungi The yeasts and common moulds are grown on Malt Extract Agar slopes in screw-cap Universal bottles. To maintain growth, a few spores are trans- ferred to a fresh slope using a sterile needle or small loop. Mould cultures are incubated at 22 ø for about a week. Yeasts are incubated at 30 ø for 3 days. If growth is satisfactory, the culture is transferred to a refrigerator (5-10 ø ) or incubated at room temperature in the dark. To prevent drying, cultures may be preserved under oil and by this method will maintain their viability for a longer period of time. The cultures should be covered with sterile liquid paraffin oil (sterilized at 160 ø for 1-2 h in a hot-air oven). The screwcaps of the bottle should be tightened and the cultures stored ver- tically in the usual way. Sub-cultures may be taken at any time almost as easily as from an agar slope. To maintain viability, transfers should be made about twice a year although a few species will require to be sub-cultured after 3 months (3). Sub-culture to corn meal agar (Oxoid Granules CM103, Tablets CM104) is recommended for the maintenance of most fungi, especially the black pigmented varieties. REFERENCES (1) Norris, J. R. and Ribbons, D. •r. (Editors). Methods in microbiology $A (1970) (Academic Press, London). (2) Cowan, S. T. and Steel, I(. J. Manual for the identification of medical bacteria 176 (1966) (Cambridge University Press, London). (3) Smith, G. An introduction to industrial mycology 5th Edn. 300-313 (1960) (Edward Arnold l,td., London).

HYGIENIC MANUFACTURE AND PRESERVATION 797 2. SOURCES OF STOCK CULTURES OF MICRO-ORGANISMS 2.1 Collection o f fungus cultures.' The Curator, Commonwealth Mycological Institute, Kew, Surrey. 2.2 Industrial bacteria, bacteria for microbiological assay, etc..' The Curator, National Collection of Industrial Bacteria, Torry Research Station, Aberdeen, Scotland. 2.3 Yeasts (non-pathogenic).' The Curator, National Collection of Yeast Cultures, The Brewing Industry Research Foundation, Nut field, Surrey. 2.4 Bacteria pathogenic to man and animals: The Curator, National Collection of Type Cultures, Central Public Health Laboratory, Colindale Avenue, London, N.W.9. 2.5 Collection of strains of algae, bacteria, bacteriophages, fungi, and protozoa: The American Type Culture Collection, 12301 Parklawn Dri,ve Rock- ville, Maryland 20852, U.S.A. 2.6 Deposition of cultures Research and industrial organizations may deposit cultures of micro- organisms which are of industrial or research interest with the curators of 2.1 and 2.2. The name of the micro-organism (genus and species) along with details of special properties and applications should be listed, e.g. spoilage organisms suitable for preservation testing. 2.7 type culture collections for use as test organisms Escherichia coli Escherichia coli Klebsiella aerogenes Proteus morganii Proteus vulgaris Recommended strains of bacteria obtainable from NCTC(2.4) ATCC(2.$) 8 196 11 229 15 380 418 10 041 4 635 NCNB(2.2) 9 517