Emperical Culture Media

Natural / Emperical Culture Media

	Natural / Emperical Culture Media These were widely used in early days of microbiology. These include milk, urine, diluted blood, vegetable juices, meat extracts and infusions etc. Most empirical media contain either only or a major ingredient, peptone (a trypsinized or hydrolysed protein). Peptone sources are animals (meat or casein) or vegetables' (soyabeans, cotton seeds). In composition peptones are mixtures containing in only partly known concentrations and identity, a variety of peptides and polypeptides, proteoses, amino acids, carbohydrates etc. including inorganic and many organic micronutrients.
Peptones provide in soluble and assimilable form all the P, S and essential mineral content of living material as well as the organic C and N sources. Among meat extracts and infusions, beef tea (beef extract) and an aqueous meat infusion made by infusing (soaking) fresh, ground meat in water are common ingredients of media useful for many species. Beef infusions are rich in minerals, organic micronutrients, proteins, protein derivatives and carbohydrates. They are often supplemented with 1 % peptone or yeast extract. Culture fluids made from beef infusions are commonly called infusion broth, whereas those made from beef extract as extract broth. All such empirical media including simple solutions of peptones or yeast extracts, are sometimes loosely included in the general terms nutrient broth or nutrient solution.
Fresh extracts of vegetables as tomato, oranges etc. are used for many bacteria, yeasts and molds. To any of the empirical media, one may add many different substances for different purposes (as a choice for a specific bacterium). These then become special media. For example, blood, which contain a great variety of carbohydrates, esters, alcohols, glucosides etc. is added to an infusion broth, which then is named as blood-infusion broth. Lactose may be added to broth and known as lactose broth.

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