Role of Megasphaera elsdenii in the Fermentation of dl -[2- ¹³ C]lactate in the Rumen of Dairy Cattle

Abstract

Since Megasphaera elsdenii ferments a variable part of DL-lactate to butyrate, measurement of the percentage of DL-lactate fermented to propionate via the acrylate pathway in rumen contents will underestimate the participation of M. elsdenii in the DL-lactate fermentation. The percentage of DL-[2-13C]lactate fermented via the acrylate pathway and the percentage of DL-lactate fermented to butyrate can be measured with 13C-FT (Fourier transform)-nuclear magnetic resonance. On the average, the contribution of M. elsdenii to DL-lactate fermentation in the rumen of dairy cattle was found to be 74% (standard deviation, 13%), but differed with animal or diet. After feeding a cow readily fermentable carbohydrates, the contribution of M. elsdenii to the fermentation of DL-lactate increased as a consequence of catabolite repression in other DL-lactate-fermenting bacteria.High-concentrate diets induce a rapid microbial fermentation in the rumen and the accumulation of intracellular (H) within the microbes leads to an increased formation of reduced end products and of lactic acid (4). This in itself should not lead to DL-lactate accumulation in the rumen, provided that the capacity to remove DL-lactate was high enough. DL-Lactate formed in the rumen may be removed in three ways: (i) by passage to the lower gastrointestinal tract, (ii) by absorption directly from the rumen, and (iii) by microbial fermentation.Megasphaera elsdenii, a predominant DL-lactate-fermenting organism, shows no catabolite repression by carbohydrates such as glucose and maltose, whereas Selenomonas ruminantium subsp. lactilytica, another predominant DL-lactate-fermenting organism, ferments glucose, sucrose, and xylose first before fermenting DL-lactate (7, 11).M. elsdenii is commonly considered to be associated with the fermentation of readily fermentable carbohydrates (9,14). Therefore, it is important to know the participation of M. elsdenii in the fermentation of DL-lactate under several feeding conditions, in different animals, and especially after feeding readily fermentable

Microbiome analysis of dairy cows fed pasture or total mixed ration diets

“…In particular, higher abundances of members of the Prevotellaceae, Erysipelotrichaceae and Veillonellaceae were observed in cows fed pasture. Very little is known about the metabolism of the Erysipelotrichaceae (Verbarg et al, 2004); however, both the Prevotellaceae and the Veillonellaceae include members that are known to produce propionate as a major fermentation product (Sijpesteijn & Elsden, 1952;Chen & Wolin, 1981;Counotte et al, 1981;Strobel & Russell, 1991;Strobel, 1992;Kishimoto et al, 2006;Chiquette et al, 2008). The abundance of the Veillonelaceae in particular was around three times higher in cows fed pasture, comprising up to 3% of all sequences.…”

Characterization of rumen bacterial diversity and fermentation parameters in concentrate fed cattle with and without forage

“…Selenomonas ruminantium has been found to synthesize propionate, malate, and lactate from primary fermentation products such as pyruvate and succinate (Hungate 1966;Evans and Martin 1997). Unlike M. elsdenii, which shows no catabolite repression by carbohydrates such as glucose and maltose, S. ruminantium first ferments glucose, sucrose and xylose prior to fermenting dl-lactate, substrates that rapidly become limiting in the liquid because of the fact they can be used by a variety of bacterial species (Counotte et al 1981).…”

Factors affecting lysine degradation by ruminal fusobacteria

“…However, the increase was only 1 log; the highest count was less than 10 7 g À 1 . In contrast, Megasphaera elsdenii, another ruminal lactate utilizing species, has counts 410 8 g À 1 if cattle are fed grain (Counotte et al, 1981), and it grows well in continuous culture at pH 5.6 with 44 mM volatile fatty acids (Russell & Dombrowski, 1980). Extrapolations of pure culture experiments to the rumen should always be made with caution, but the idea that lysine-utilizing fusobacteria are not apt to be significant in cattle that are fed commercial rations was supported by two other observations.…”