By growing Aspergillus parasztzcus (C.M.I. 15957) under controllcd conditions on sterilized peanuts an average of 265 nig. of aflatoxin per kilogram of peanuts has been produced and subsequently isolated. Other strains from the A . fluz~usoryzae group gave lower yields of aflatoxin and one such strain gave aflatoxin froni which certain normal coinponents were absent. The aflatoxin produced on sterilized peanuts by any particular strain of A . fivus-oryzue was shown by thin-layer chromatography to contain the same major components as were produced by that strain on unsterilized whole peanuts.

I n three series of experiments, 3-l., 20-l., and 150-1. barterial cultures were grown in stirred, deep culture vessels to average bacterial cell densities of 71 X lo8, 63 X lo8, and 43 x 10s viable organism per milliliter, respectively, and then infected with phage. The average yield of progeny phage in each case wm ca. 3000 mpfu (minimum plaque-forming units) per cell. Thus, the average mash of phage obtained in the 3-1. experiments was not less than 124 mg./l., Calculated from the plaque counts, assuming a particle size of 3.6 x 106 Daltons for the p2phage. This is about twentyfold higher than is obtainable by conventional methods in aerated, shaken culture flasks. The actual phage yields are probably much higher than the minimum values calculated from plaqlie ronnts. For example, in the case of one of our culture lysates which was purified at King's College, the effiriency of plating was shown to be only 19%. The carbon dioxide evolution rate of cultures was measured and used as a gidde to the time at which phage should be added. In this way, greater control of cultural conditions was obtained than is possible in shaken flasks. For the best yield of phage per milliliter of culture, the optimum time for phage infection WEB such that bacterial lysis just prevented the carbon dioxide evolution rate from reaching its potential maximum. The major factor influencing the phage yield per milliliter of cultrire was the aeration capacity of the culture vessel used. All had maximum aeration capacities much higher than those obtainable in shaken culture flasks. Cultures grown and infected in a 3-1. vessel operated under conditions of low aeration gave poor yields of phage. The reasons for this are discussed.

The thermophilic bacterium Bacillus slearolhermophilus (ATCC 7954, NCA 1503, NCIB 8924) has been shown to produce high levels of the enzyme alcohol dehydrogenase,l.z amounting to 1-254 of the soluble cell protein when grown in complex media3 containing sucrose. This enzyme is also produced in continuous culture.' Alcohol dehydrogenase (AIlH) is known to be responsible for the t,erminal step in the formation of alcohol by yeasts, and, in the course of investigat,ions of H . stearothermophilus as a source of thermostable proteins,5 we briefly examined it.s ability t o produce alcohol under anaerobic conditions at high temperatures and the possibility of removing any alcohol so produced by stripping with an inert gas. This study reports alcohol production by h ' . stearothermophilus

Bacteriophage T7 was grown with Escherichia coli B as the host organism in 3and 20-liter vessels. Under the best growth conditions devised, the yields of T7 in the culture lysates averaged 1.33 X 1012and 0.95 X 1012plaque-forming units per ml, respectively, compared with the best previously reported yields of 1011 to 3 x 101" plaque-forming units per ml in 1-liter batches grown in the presence of air, or double this in similar batches grown in the presence of oxygen. The bacteriophage was purified by a simple method which gave average yields of 143 mg/liter and 131 mg/ liter from the 3-and 20-liter batches, respectively. The efficiency of plating of the final material ranged from 18 to 42%. The purified bacteriophage is a convenient source of monodisperse deoxyribonucleic acid, the molecular weight of which is about 25 X 106.

No abstract