Stock solution A contained per 100 ml of distilled water
5 mg thiamine HCl, 10 mg pyridoxin HCl, 5 mg calcium
pantotenic acid, 5 mg riboflavin, 10 mg nicotinic acid, and
1 mg p-aminobenzoic acid. Stock solution B contained 5 mg
D-(+)-biotin and 50 mg folic acid in 100 ml of water. Stock
solutions A and B were sterilized by filtration through a
0.45 μm filter (Millipore) before addition to the medium. The
pH value of the medium was then adjusted to 4.5.