A medium for commercial production of the halophilic Micrococcus nuclease

A simple synthetic medium (glutamate–sucrose medium) was devised for production, during growth in shaken flasks, of extracellular halophilic nuclease (nuclease H) by a moderate halophile, Micrococcus varians subsp. halophilus. A simple medium consisting of 0.7% ammonium sulfate, 1.0% glucose, minerals, three vitamins, and 2 M NaCl gave good growth and excellent production of nuclease H in a jar fermentor when the pH was adjusted to 7.5 to 8.0 during cultivation.

An improved assay method for neutralizing antibodies against influenza viruses

1. A method has been developed for the assay of antisera against influenza viruses.2. Surviving bits of allantois-on-shell serve as host tissue, eighty to one hundred units being provided by a single egg. The test is set up in plastic trays, and uses a simple synthetic medium.3. The method has worked equally well with the ten representative strains of influenza virus tested. It surpasses the orthodox techniques of neutralization in mice or whole eggs as regards sensitivity, accuracy and economy.

EFFECT OF FERROCYANIDE ON GROWTH AND ACID PRODUCTION OF ASPERGILLUS NIGER

Growth of Aspergillus niger, in a simple synthetic medium, is inhibited by ferrocyanide ion in concentrations below 1 p.p.m. This inhibition can be reversed by increasing the iron and zinc concentration of the medium. Acid production, however, is inhibited only 50% by 200 p.p.m. ferrocyanide and this inhibition is not reversible by trace metals. Neither the inhibition of growth nor that of acid production is the result of release of cyanide from ferrocyanide. It is suggested that ferrocyanide has at least two functions in the treatment of substrates for use in the production of citric acid. The first is to remove deleterious trace metals from the medium whereas the second is to act as a direct inhibitor of growth of the mold.

NITROGEN AND VITAMIN REQUIREMENTS OF PSEUDOMONAS HYDROPHILA

Yeast extract and vitamin-free casamino acids were found to be equivalent as sources of nitrogen for the growth of Pseudomonas hydrophila in a glucose – mineral salts medium. The addition of a mixture of thiamine, riboflavin, pantothenic acid, pyridoxine, nicotinic acid, para-aminobenzoic acid, biotin, and folic acid to the medium containing vitamin-free casamino acids did not stimulate growth. About 67% as much growth was obtained with a mixture of 20 amino acids and asparagine as with the vitamin-free casamino acids and the mixture could be replaced by any one of asparagine, aspartic acid, serine, and alanine. Of the 11 simple nitrogen compounds tested, including urea, nitrates, and ammonium salts, only ammonium citrate and dibasic ammonium phosphate were utilized appreciably. A simple synthetic medium consisting of ammonium citrate, glucose, and mineral salts was found to give approximately the same amount of growth as the more complex yeast extract – glucose – mineral salts medium.