|Mantovani, H - CORNELL UNIVERSITY|
Submitted to: Microbial Ecology International Symposium
Publication Type: Abstract Only
Publication Acceptance Date: August 1, 2001
Publication Date: N/A
Technical Abstract: It has long been recognized that some S. bovis produce bacteriocins, but the impact of this production on rumen ecology was not clear. A bacteriocin-producing strain (HC5) was isolated from a cow fed hay, and 16S rDNA indicated that this bacterium was closely related to other S. bovis strains. HC5, strongly inhibited S. bovis JB1, a common laboratory strain. .Large zones of clearing were observed, and the JB1 viable cell number decreased 7 logs. The bacteriocin activity was resistant to autoclaving, proteinase K and a-chymotrypsin, but it was inactivated by pronase E and trypsin. The bacteriocin was precipitated by ammonium sulfate precipitation (60% saturation), dialyzed (3,500 Da cutoff) and separated on a PAGE gel. Batch cultures did not produce the bacteriocin until glucose was depleted and the cells entered stationary phase, but continuous cultures also produced bacteriocin. Bacteriocin production was maximal at a dilution rate of 0.3 h per h and affected by growth pH. S. bovis JB1 can become highly nisin resistant, but even nisin-resistant JB1 cultures were sensitive to the HC5 bacteriocin. We are currently assessing the ability of HC5 to inhibit freshly isolated strains, and results indicate that HC5 can inhibit some bacteriocin-producing S. bovis.