SummaryEquipment for the sterilization of air by heat with capacities of 140 l./min., and 1700 l./min. respectively is described. An improved method for testing sterility is given.

A method for the growth of Clostridium pasteurianum in a 140-liter (total capacity) stainless-steel vessel is described. By preventing the p H value from falling below 5.6, the growth of cultures was prolonged. Larger amounts of the carbon source (sucrose) and the nitrogen source (ammonium ion) were supplied and consumed, and cell yields of up to 5.56 g (dry weight) per liter were obtained. The highest cell yield previously reported was 1.7 g (dry weight) per liter obtained under nitrogen-fixing conditions in 500-ml cultures. The ferredoxin content of the cells was comparable with that obtained by earlier workers.

A method for the anaerobic growth of Thiobacillus denitrificans in a 140-liter (total capacity) stainless-steel culture vessel is described. As a result of controlling the p H value of cultures, and of ensuring that certain essential nutrients were in excess, cell yields approaching 700 mg (dry weight) per liter were obtained. These were over threefold higher than the best yields hitherto reported. The average rhodanese content of the cells from four cultures was 176,000 units per gram (dry weight). Adenosine-5′-phosphosulfate reductase (average content, 238 units per gram dry weight) and adenylate kinase (average content, 15,300 units per gram, dry weight) were also present.