Submitted to: Conference on Rumen Function
Publication Type: Abstract Only
Publication Acceptance Date: 11/16/2000
Publication Date: 11/16/2000
Citation: MANTOVANI, H.C., RUSSELL, J.B. THE ROLE OF LIPOTEICHOIC ACIDS IN THE RESISTANCE OF STREPTOCOCCUS BOVIS TO NISIN. CONFERENCE ON RUMEN FUNCTION. 2000.
Technical Abstract: Previous work indicated that nisin and monensin had similar effects on ruminal fermentation in vitro, but it was unclear if ruminal bacteria could become nisin-resistant. Streptococcus bovis JB1 was initially inhibited by nisin (1 uM), and viability decreased 3 logs. However, some of the cells survived, and these nisin-resistant cells grew as rapidly as untreated ones. Nisin-resistant cultures remained nisin-resistant even if nisin was not present, but competition studies indicated that nisin-sensitive cells could displace the resistant ones if nisin was not present. Fresh isolates were initially as nisin sensitive as the wild type S. bovis JB1, but they also developed nisin resistance. Nisin-sensitive, glucose-energized cells lost virtually all of their intracellular potassium if 1 uM nisin was added, but resistant cells retained potassium even after 10 uM nisin was added. Nisin-resistant cells were less hydrophobic and more lysozyme-resistant than nisin-sensitive cells. Because the nisin-resistan cells bound less cytochrome c, it appeared that nisin was being excluded by a net positive (less negative) charge. Nisin-resistant cells had more lipoteichoic acid than nisin-sensitive cells and de-esterified lipoteichoic acids from nisin-resistant cells migrated more slowly through a polyacrylamide gel than those from nisin-sensitive cells. These results indicated that lipoteichoic acids could be modified to increase the resistance of S. bovis to nisin. S. bovis JB1 cultures were still sensitive to monensin, tetracycline, vancomycin and bacitracin, but ampicillin resistance was 1000-fold greater.