Fig. 7

Ammonia content of Bacillus subtilis cultures assessed over a period of 5 days at minimal medium supplemented with four levels of four salts of calcium (a: acetate, b: citrate, c: chloride and d: nitrate). Cultures started at 0-time with O.D.660 nm of 0.2A accounting to 21 × 107 cells/mL. Statistical analysis as shown in Fig. 2.