CAPSULATION OF PROPIONIBACTERIUM1

Abstract

Strains of nine species of Propionibacterium were examined for slime and/or capsule formation. Direct evidence of capsules was demonstrated by negative staining with India ink. Changes in viscosity of growth media, estimated using an Ostwald viscosimeter, were related to capsule or slime production. Mucoid colony production provided further evidence of slime formation. Under the criteria and experimental conditions adopted, at least one strain of each species and 34 of 82 strains formed slime. Incubation temperatures of 15 and 21 C which are less than optimal for growth, adjustment of media pH above neutrality, addition of sodium chloride, and as many as 11 different carbohydrates were conducive to slime formation. Paper and thin-layer chromatographic analyses of acid-hydrolyzed capsular material indicated that it contained mannose and lesser amounts of glucose and galactose.