Production of Bacillus cereus exopenicillinase on a pilot‐plant scale

A substrain of Bacillus cereus 569/H produced above 10,000 units of penicillinase/ ml. when grown in a pilot‐plant fermentor using a medium containing Casamino acids techn. (Difco) or N‐Z‐Amine type B (Sheffield), and salts. Simplified purification and concentration procedures give an overall yield of 50‐65% enzyme. The freeze‐dried enzyme preparation had a good storage stability in vacuumsealed ampules kept at 4, 30, and 37°C. In vials containing air in the head space, partial inactivation occurred in two months at 30 and 37°C. The freezedried preparation showed satisfactory performance in the production of yoghurt fermented milk.