Bibersteinia trehalosi Inhibits the Growth of Mannheimia haemolytica by a Proximity-Dependent Mechanism

• Published in: Applied and Environmental Microbiology 2010-02, Vol.76 (4), p.1008-1013
• Main Authors: Dassanayake, Rohana P, Call, Douglas R, Sawant, Ashish A, Casavant, N. Carol, Weiser, Glen C, Knowles, Donald P, Srikumaran, Subramaniam
• Format: Article
• Language: English
• Subjects: Agar; Animal diseases; Animals; Bacteria; Bacteriological Techniques; Bacteriology; Base Sequence; Biological and medical sciences; Colony Count, Microbial; DNA, Bacterial - genetics; Experiments; Fundamental and applied biological sciences. Psychology; Mannheimia haemolytica; Mannheimia haemolytica - genetics; Mannheimia haemolytica - growth & development; Mannheimia haemolytica - pathogenicity; Mannheimia haemolytica - physiology; Microbial Ecology; Microbiology; Models, Biological; Pasteurella - genetics; Pasteurella - growth & development; Pasteurella - pathogenicity; Pasteurella - physiology; Pasteurella multocida - growth & development; Pasteurella multocida - pathogenicity; Pasteurellaceae Infections - microbiology; Pasteurellaceae Infections - veterinary; Physical growth; Pneumonia, Bacterial - microbiology; Pneumonia, Bacterial - veterinary; Sheep; Sheep Diseases - microbiology; Sheep, Bighorn
• ISSN: 0099-2240; 1098-5336; 1098-6596
• DOI: 10.1128/AEM.02086-09

Mannheimia (Pasteurella) haemolytica is the only pathogen that consistently causes severe bronchopneumonia and rapid death of bighorn sheep (BHS; Ovis canadensis) under experimental conditions. Paradoxically, Bibersteinia (Pasteurella) trehalosi and Pasteurella multocida have been isolated from BHS pneumonic lungs much more frequently than M. haemolytica. These observations suggest that there may be an interaction between these bacteria, and we hypothesized that B. trehalosi overgrows or otherwise inhibits the growth of M. haemolytica. Growth curves (monoculture) demonstrated that B. trehalosi has a shorter doubling time (~10 min versus ~27 min) and consistently achieves 3-log higher cell density (CFU/ml) compared to M. haemolytica. During coculture M. haemolytica growth was inhibited when B. trehalosi entered stationary phase (6 h) resulting in a final cell density for M. haemolytica that was 6 to 9 logs lower than expected with growth in the absence of B. trehalosi. Coculture supernatant failed to inhibit M. haemolytica growth on agar or in broth, indicating no obvious involvement of lytic phages, bacteriocins, or quorum-sensing systems. This observation was confirmed by limited growth inhibition of M. haemolytica when both pathogens were cultured in the same media but separated by a filter (0.4-μm pore size) that limited contact between the two bacterial populations. There was significant growth inhibition of M. haemolytica when the populations were separated by membranes with a pore size of 8 μm that allowed free contact. These observations demonstrate that B. trehalosi can both outgrow and inhibit M. haemolytica growth with the latter related to a proximity- or contact-dependent mechanism.