Effect of Monensin and Lasalocid-Sodium on the Growth of Methanogenic and Rumen Saccharolytic Bacteria

Abstract

It is thought that monensin increases the efficiency of feed utilization by cattle by altering the rumen fermentation. We studied the effect of monensin and the related ionophore antibiotic lasalocid-sodium (Hoffman-LaRoche) on the growth of methanogenic and rumen saccharolytic bacteria in a complex medium containing rumen fluid. Ruminococcus albus, Ruminococcus flavefaciens, and Butyrivibrio fibrisolvens were inhibited by 2.5 ,ug of monensin or lasalocid per ml. Growth of Bacteroides succinogenes and Bacteroides ruminicola was delayed by 2.5 Ag of monensin or lasalocid per ml. Populations of B. succinogenes and B. ruminicola that were resistant to 20 ,sg of either drug per ml were rapidly selected by growth in the presence of each drug at 5.0 ,ug/ml. Selenomonas ruminantium was insensitive to 40 ,ig of monensin or lasalocid per ml. Either antibiotic (10 ,g/ ml) inhibited Methanobacterium MOH, Methanobacterium formicicum, and Methanosarcina barkeri MS. Methanobacterium ruminantium PS was insensitive to 40 ,ug of monensin or 20 ,ug of lasalocid per ml. The methanogenic strain 442 was insensitive to 40 ,ug of monensin but sensitive to 10 ,tg of lasalocid per ml. cus albus 7, Ruminococcus flavefaciens C94, Bacteroides succinogenes S85, Bacteroides ruminicola GA33, Butyrivibrio fibrisolvens strains Dl, 49, and A38, Selenomonas ruminantium strains GA192, HD4, D, GA31, and PC18, Methanobacterium strain MOH, Methanobacterium ruminantium PS, Methanobacterium formicicum MF, and Methanosarcina barkeri MS were obtained from the culture collection of the

Potentiation by metal ions of the efficacy of the ionophores, monensin and tetronasin, towards four species of ruminal bacteria

“…The selective toxicity of ionophores towards certain ruminal bacteria is a function of their ability to permeate the cell envelopes of some bacteria but not others (Chen & Wolin, 1979;Henderson et al, 1981;Bergen & Bates, 1984;Nagaraja & Taylor, 1987;Newbold et al, 1988;Russell & Strobel, 1989). Ionophores by definition translocate ions through biological membranes (Pressman, 1968), and this has been assumed to be their mode of action at the cellular level: ionophores that permeate the cell envelope will then disrupt transmembrane ionic gradients in accordance with their ion-translocating properties and cause toxicity.…”

“…Their nutritional effects are due largely to changes in the fermentation stoichiometry and the metabolism of dietary nitrogen by ruminal microorganisms (Bergen & Bates, 1984;Russell & Strobel, 1989;Duffield et al, 2012). These changes arise partly from the elimination of many Gram-positive bacteria (Chen & Wolin, 1979;Henderson et al, 1981;Nagaraja & Taylor, 1987;Newbold et al, 1988) and partly from adaptations which resistant Gram-negative bacteria undergo when grown in the presence of ionophores (Morehead & Dawson, 1992;Newbold et al, 1992;Callaway & Russell, 1999).…”

Ionophore resistance of ruminal bacteria and its potential impact on human health

“…In vitro and in vivo experiments indicate that monensin decreases methane production, but methanogenic bacteria are not particularly sensitive to ionophores [29]. When mixed ruminal bacteria are incubated with H 2 and CO 2 , little decrease in methane is observed [29], but monensin can inhibit H 2 -producing ruminal bacteria that supply methanogens with H 2 [30]. Because bacteria that produce H 2 are more apt to produce acetate and butyrate than those that produce succinate and propionate, there is a change in ruminal fermentation acids (Fig.…”

The effect of bovicin HC5, a bacteriocin from Streptococcus bovis HC5, on ruminal methane production in vitro

“…The ionophore, monensin, decreases the methane production of cattle, but it does not seem to have a primary e¡ect on methanogens [5]. When mixed ruminal bacteria were treated with monensin, methane production from hydrogen and carbon dioxide did not decrease [6], and later work showed that monensin was inhibiting carbohydrate fermenting bacteria that produced hydrogen [7]. Monensin decreased methane production from formate [8], but Hungate demonstrated that ruminal formate was converted to hydrogen and carbon dioxide before it was consumed by methanogens [9].…”