UREA-HYDROLYZING BACILLI I

Publisher Website
Google Scholar
Abstract
Twenty-four strains of mesophilic, urea-hydrolyzing members of the genus Bacillus were isolated from soils by urea-enrichment technique. There were 2 distinct physiological categories. Eury-responsive strains, widely responsive to the pH of the growth medium, grew well upon a nutrient medium (without added urea) at pH values from 5 to 11. Steno-responsive strains, narrowly responsive to pH, exhibited slight growth, and that only at pH 9 to 11, on media unsupplemented with urea. Biochemical identification was made of a strain of B. lentus, but there were no other relationships of diagnostic aid. Comparative physiological characterization of 26 known strains of Bacillus spp. afforded a presumptive identification of B. pasteurii. The fact that steno-responsive cultures require free ammonia in addition to amino acids tends to validate the 2 physiological categories. Eury-responsive species are B. freudenreichii, B. loehnisii, B. lentus, and some strains of B. sphaericus. Ability to hydrolyze urea appears to be of significant determinative value for the genus.