[A statistical method for the determination of the yield correlation of antibiotic-producing microorganisms].
The antibiotic yields of industrial selectants must be checked at several steps of cultivation. Here the question arises whether the activities at the different levels of cultivation are correlated. The common coefficient of correlation cannot be used because repeated determinations of the yield at one selectant result in different values. In order to have only one fixed value per selectant we define the mean value around which the observed values are varying. But these mean values cannot be observed. Thus, an adequate method of correlation similar to that in Guiard and Herrendörfer (1977) was used. The method is demonstrated in two examples: With selectants of Streptomyces noursei for streptothricin titers in 20 ml- and 20 l-cultures as well as with selectants of Penicillium chrysogenum for potency indices in surface cultures and penicillin titers in 50 ml submerged cultures, respectively. In both cases the coefficients of correlation were above 0.7.
Das Autoselect‐System – ein Automatensystem zur Selektion von Antibiotikaproduzenten. VI. Achtfach‐Stanzautomat
An eightfold punch belonging to the Autoselect-system is described. It is provided for the preparation of bioassay plates. From the agar of large quadratic test plates moving automatically on a carriage of the machine, 64 holes are made by eight punches. The punches arranged in a row over the test plate are lowered, if the carriage stops, and so they cut out and exhaust agar discs in a pattern of 8 × 8.
Control of stock culture preservation and inoculum build‐up in bacterial fermentation
Control of product quality throughout repeated fermentations depends upon maintenance of genetic uniformity from the time of strain selection until the product is harvested. Genetic control, therefore, must be maintained for stock cultures, and during inoculum preparation and growth to produce the product. Theoretical and applied aspects of a procedure that will accomplish this control are discussed. A specific procedure adaptable to situations in which a ‘seed’ is repeatedly increased to produce a larger quantity of a final material is described. The procedure was tested by comparing the product of three bacterial species grown by a standard or usual vs. recommended or experimental procedure comparing product quality and uniformity. Use of the recommended procedure resulted in the high production of a uniform product based on the maintenance of the colony type of Bacillus anthracis, colony colour and type of Serratia marcescens, and uniformity and amount of toxin produced by Clostridium botulinum type A.