This heading covers various preparations in which bacteria, moulds, microbes, viruses, other micro-organisms and plant, human or animal cells required for medical purposes (e.g., for obtaining antibiotics) or for other scientific purposes or in industry (e.g., in the manufacture of vinegar, lactic acid, butyl alcohol) can find nourishment and multiply or in which they can be maintained.
They are usually prepared from meat extracts, fresh blood or blood serum, eggs, potatoes, alginates, agar‑agar, peptones, gelatin, etc., and often contain additional ingredients such as glucose, glycerol, sodium chloride, sodium citrate or dyes. Acids, digestive ferments or alkalis may be added to bring them to the required degree of acidity or alkalinity, etc. There are also other media, e.g., mixtures of sodium chloride, calcium chloride, magnesium sulphate, potassium hydrogensulphate, potassium aspartate and ammonium lactate in distilled water. Certain culture media for viruses consist of living embryo. They are usually in liquid form (broths), pastes or powders but may also be in tablets or granule form, and are sterilised and put up in sealed glass bottles, tubes, ampoules or tins. The heading does not cover products not prepared as culture media, e.g. :(a) Agar‑agar (heading 13.02). (b) Blood or egg albumin (heading 35.02). (c) Gelatin (heading 35.03). (d) Peptones (heading 35.04). (e) Alginates (heading 39.13).
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