FLAVOBACTERIUM SUAVEOLENS, A NEW SPECIES OF 
AROMATIC BACILLUS ISOLATED FROM DAIRY WASTES 1 
By Lulu Soppeland 
Iowa State College of Agriculture and Mechanic Arts and Iowa Engineering 
Experiment Station 
INTRODUCTION 
In a large group of organisms isolated from dairy wastes were found 
several which produced an aromatic odor from all of the mediums containing 
protein. The odor is sweet-scented, very pleasing during the first two days' 
incubation at 22° C. but in four to six days it changes to a decided cheesy odor 
which persists for two months. At 37° the cheesy odor develops in two days. 
During the three years these organisms have been under observation, this property 
of aroma production has always been manifested in subcultures, appareptly undi¬ 
minished in intensity. 
As the aroma-producing property seemed to be associated with the nitrogenous 
organic matter in the medium, it was anticipated that the organism was an 
active proteolyzer. Inoculated into a lj per cent gelatin with an initial P* of 
7.3 and held at 22° C. for six days, the amino and ammoniacal nitrogen increased 
from 50 to 950 p. p. m. Inoculated into skim milk and kept under similar 
conditions, the amino and ammoniacal nitrogen increased from 30 to 300 p. p. m. 
MORPHOLOGY 
Smears from plain agar (12 hours—7 days) are always Gram-negative. Milk 
powder agar cultures, 12 to 16 hours old, are Gram-positive and become Gram¬ 
negative on further incubation; spores were not observed when tested by spore 
stains (24-hour to 7-day old agar culture) or by exposure to temperatures of 60° to 
80° C.; growth was not obtained after heating either a young or old culture at 
60° for 10 minutes or at 80° for 5 minutes; size varies from 1.0/* to 1.2/* by 0.6/< 
to 0.8/*; rods have rounded ends; actively motile, position of flagella peritrichous. 
CULTURAL CHARACTERISTICS 
Records are for 22° C. for 48 hours unless otherwise stated. The P H of media 
employed ranged from 6.5 to 7.5 
Nutrient-agar slant. —Growth is moderate, filiform, flat, glistening, opaque, 
of butyrous consistency and produces an aromatic odor; pigment is yellow— 
510.033 shade 2 1 ; pigment is insoluble in water, methyl, ethyl, and isoamyl 
alcohols, benzene, carbon tetrachlorid, and xyol; readily soluble in acetone and 
slowly soluble in ether and chloroform; in 6 days growth is oleaginous. 
Nutrient-agar plates. —Colonies small, growth similar to slant; confluence 
marked in seven days. 
Milk powder agar slant. —Similar to plain agar but growth more abundant 
and color deeper—420.042 shade 3 1 ; proteolysis distinct. 
Nutrient broth. —Moderate uniform clouding, scanty sediment; no surface 
growth; an aromatic odor which changes to cheesy in four days. 
Gelatin stab. —A stratiform liquefaction is visible in one-half day; gelatin 
completely liquefied in six days; medium brownish and white precipitate set¬ 
tles at bottom by sixth day. 
Potato slant. —Abundant growth, color more intense than on nutrient or 
milk powder agar—330.051 shade 3 1 . 
1 Received for publication Jan. 26, 1924. 
Journal of Agricultural Research, 
Washington, D. C. 
88287—24f-6 
Vol. XXVIII, No. 3 
April 19,1924 
Key No. Iowa-8 
(275) 
