This International Standard specifies a horizontal method for the enumeration of viable mesophilic lactic acid bacteria by counting the colonies growing in a solid medium after incubation at 30 °C for 3 days. NOTE In some food products, there exist psychotrophic or thermophilic lactic acid bacteria necessitating culture temperatures different from 30 °C. Moreover, not all lactic acid bacteria grow on MRS agar at pH 5,7 and some grow only weakly. Subject to the limitations discussed in the introduction and in the note above, this International Standard is applicable to products intended for human consumption or animal foodstuffs