Author
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MANTOVANI, H - CORNELL UNIVERSITY |
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Russell, James |
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Submitted to: North Eastern Microbiologists Physiology Ecology and Taxonomy Abstracts
Publication Type: Abstract Only Publication Acceptance Date: 6/1/2001 Publication Date: N/A Citation: N/A Interpretive Summary: Technical Abstract: Ruminal fluid from a cow fed hay had rapidly growing, lactate producing bacteria that could inhibit nisin-sensitive and nisin-resistant S. bovis JB1 cells, and 16S rDNA sequencing indicated that the most active strain (HC5) was closely related to other S. bovis. The inhibitory activity of S. bovis HC5 was not due to a bacteriophage, and the inhibition could be reversed by pronase E and trypsin. Batch cultures of S. bovis HC5 did not produce bacteriocin until glucose was depleted and cells entered stationary phase, but slow dilution rate continuous cultures (0.2 h-1) had as much bacteriocin activity as stationary phase cultures. Because the activity of continuous cultures (0.2 to 1.2 h-1) was inversely related to the glucose consumption rate, it appeared that bacteriocin production was being catabolite repressed by glucose. When the pH of continuous cultures (0.2 h-1) was decreased from 6.7 to 5.4, bacteriocin production increased 1-fold, but bacteriocin production declined at pH values less than 5.0. Continuous cultures (0.2 h-1) that had only ammonia as a nitrogen source produced some bacteriocin, but Trypticase addition caused a 1.5-fold increase in cell protein and 2.0 fold decline in the amount of HC5 protein that was needed to prevent S. bovis JB1 growth. Because S. bovis JB1 cultures that had been transferred with sub-lethal doses of S. bovis HC5 bacteriocin never became resistant, it is conceivable that S. bovis HC5 could have a significant impact on S. bovis ecology in vivo. |
