Stalactite growth in ghee broth is due to the following organism?

Cultural characteristics of Yersinia pestis: 1. When grown in a flask of broth with oil / ghee floated on top (ghee broth) a characteristic growth occurs which hangs down into the broth from the surface, resembling stalactite. 2. On nutrient agar, colonies are small, delicate, transparent discs, becoming opaque on continued incubation. 3. On blood agar colonies are dark brown due to absorption of the hemin pigment. 4. On MacConkey agar colourless colonies are formed. 5. In broth a flocculent growth occurs at the bottom and along the sides of the tube. Ref: Textbook of Microbiology Ananthanarayanan, 8th edition