Yeast extract-peptone-ethanol medium

Dissolve 20 mL ethanol in 200 mL distilled water and sterile filter through an 0.45 pm membrane. Add this solution to the tempered autoclaved media prepared in step 3 above and prior to pouring plates. 

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To select acetic acid bacteria from a number of the strains isolated, it is suitable to test the strains for growth on a pH 3.5 medium, which contains, for example, 1.0 % D-glucose (w/v), 0.5 % ethanol (99.8 %) (v/v), 0.3 % peptone (w/v), and 0.2 % yeast extract (w/v) the pH is adjusted to 3.5 with hydrochloric acid (Yamada et al. 1999). A pH 4.0 medium can be used for the growth test. If a certain strain is an acetic acid bacterium, appropriate growth can be seen. If the pH of the medium is adjusted to 4.5, bacteria other than acetic acid bacteria sometimes can grow. 

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