FIG. 5.

Schematic representation of the functions of urease in B. cereus. Urea is hydrolyzed by urease (EC 3.5.1.5), forming carbon dioxide and ammonia. Subsequently, ammonia is converted into ammonium, which causes the pH to increase and may serve low-pH survival. Ammonium can be used as a nitrogen source and may be included in nitrogen metabolism via two possible routes supporting bacterial growth. The involved enzymes, glutamine synthetase and aspartate-ammonia lyase, are indicated by enzyme numbers (6.3.1.2 and 4.3.1.1, respectively). Note that the sequenced ATCC 10987 strain cannot use ammonium as a sole nitrogen source. The routes and/or enzymes missing in ATCC 10987 are indicated by dashed lines.