NITROGEN AND VITAMIN REQUIREMENTS OF PSEUDOMONAS HYDROPHILA

Abstract

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.