Submitted to: Feedinfo News Service
Publication Type: Popular Publication
Publication Acceptance Date: 11/10/2003
Publication Date: 12/12/2003
Citation: Russell, J.B., Houlihan, A.J., Flythe, M.D. 2003. Improving ruminal and silage fermentations. Feedinfo News Service. Available: https://www.feedinfo.com.
Technical Abstract: Many gram-positive bacteria produce small ribosomally-synthesized peptides that have antimicrobial activity. These "bacteriocins" were first isolated from fermented dairy products, and they have been proposed as an alternative to classical antibiotics. At least one bacteriocin (nisin) has been commercially developed. In vitro experiments indicated that nisin had the same effect on ruminal fermentation as one of the most commonly used antibiotics in beef cattle rations (monensin), but this effect did not persist in vivo. To circumvent the potential problem of bacteriocin resistance, the rumen was screened for bacteria that could inhibit nisin-resistant S. bovis. Results indicated that some strains of S. bovis produced bacteriocins, and one type (S. bovis HC5) inhibited nisin-resistant strains. In vitro experiments indicated that S. bovis HC5 could inhibit ruminal organisms that produce methane and ammonia. American and European cattle consume more than 200 million tons of silage each year, and silage fermentation may be a means of delivering bacteriocins to the rumen as well as enhancing silage quality. Bacteriocin-producing bacteria have not yet been used to improve silage quality on the farm, but recent work indicates that bovicin HC5inhibited the pathogen Listeria monocytogenes. Cattle can become infected with L. monocytogenes by consuming improperly prepared silage, and this bacterium can then be transferred to humans via contaminated beef. L. monocytogenes has been responsible for several large scale beef recalls. S. bovis HC5 can also kill Clostridium sporogenes. This latter bacterium degrades amino acids, produces ammonia and increases silage pH. When the pH increases, the silage is more prone to spoilage. Because some clostridia produce toxins (e.g. Clostridium botulinum), the use of bacteriocins to inhibit other gram-positive bacteria could have yet another benefit.