Factors affecting the antibacterial activity of the ruminal bacterium, Streptococcus bovis HC5.
Streptococcus bovis HC5 inhibits a variety of S. bovis strains and other Gram-positive bacteria, but factors affecting this activity had not been defined. Batch culture studies indicated that S. bovis HC5 did not inhibit S. bovis JB1 (a non-bacteriocin-producing strain) until glucose was depleted and cells were entering stationary phase, but slow-dilution-rate, continuous cultures (0.2 h(-1)) had as much antibacterial activity as stationary-phase batch cultures. Because the activity of continuous cultures (0.2-1.2 h(-1)) was inversely related to the glucose consumption rate, it appeared that the antibacterial activity was being catabolite repressed by glucose. When the pH of continuous cultures (0.2 h(-1)) was decreased from 6.7 to 5.4, antibacterial activity doubled, but this activity declined at pH values less than 5.0. Continuous cultures (0.2 h(-1)) that had only ammonia as a nitrogen source had antibacterial activity, and large amounts of Trypticase (10 mg ml(-1)) caused only a 2.0-fold decline in the amount of HC5 cell-associated protein that was needed to prevent S. bovis JB1 growth. Because S. bovis HC5 was able to produce antibacterial activity over a wide range of culture conditions, there is an increased likelihood that this activity could have commercial application.
Mantovani
Hilário C
HC
Section of Microbiology, Cornell University, Wing Hall, Ithaca, NY 14853, USA.
Russell
James B
JB
D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001430:Bacteriocins / Q000737:chemistry / Q000494:pharmacology; D005947:Glucose / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D009994:Osmolar Concentration; D012418:Ruminants / Q000382:microbiology; D016985:Streptococcus bovis / Q000737:chemistry / Q000187:drug effects / Q000254:growth & development
D000900:Anti-Bacterial Agents; D001430:Bacteriocins; D005947:Glucose