Features of rumen and sewage sludge strains of Eubacterium limosum, a methanol- and H2-CO2-utilizing species

Abstract

Eubacterium limosum was isolated as the most numerous methanol-utilizing bacterium in the rumen fluid of sheep fed a diet in which molasses was a major component (mean most probable number of 6.3 x 108 viable cells per ml). It was also isolated from sewage sludge at 9.5 x 104 cells per ml. It was not detected in the rumen fluid of a steer on a normal hay-grain diet, although Methanosarcina, as expected, was found at 9.5 x 10i cells per ml. The doubling time of E. limosum in basal medium (5% rumen fluid) with methanol as the energy source (370C) was 7 h. Acetate, cysteine, carbon dioxide, and the vitamins biotin, calcium-D-pantothenate, and lipoic acid were required for growth on a chemically defined methanol medium. Acetate, butyrate, and caproate were produced from methanol. Ammonia or each of several amino acids served as the main nitrogen source. Other energy sources included adonitol, arabitol, erythritol, fructose, glucose, isoleucine, lactate, mannitol, ribose, valine, and H2-CO2. The doubling time for growth on H2-CO2 (5% rumen fluid, 370C) was 14 h as compared with 5.2 h for isoleucine and 3.5 h for glucose. The vitamin requirements for growth on H2-C02 were the same as those for methanol; however, acetate was not required for growth on H2-CO2, although it was necessary for growth on valine, isoleucine, and lactate and was stimulatory to growth on glucose. Acetate and butyrate were formed during growth on H2-CO2, whereas branched-chain fatty acids and ammonia were fermentation products from the amino acids. Heat tolerance was detected, but spores were not observed. The type strain of E. limosum (ATCC 8486) and strain L34, which was isolated from the rumen of a young calf, grew on methanol, H2-CO2, valine, and isoleucine and showed the same requirements for acetate as the freshly isolated strains.

Influence of hydrogenothrophic methane formation on the thermophilic anaerobic degradation of protein and amino acids

“…However, subcultivations with leucine, valine or isoleucine together with acetate did not give rise to any butyrate or caproate (results not shown). Butyrate and caproate might have been formed via hydrogen and carbon dioxide, which is a pathway used by Eubacterium limosum [29].…”

“…The decrease in the degradation of these amino acids during this period is also given. Values are means for days [20][21][22][23][24][25][26][27][28][29][30][31][32][33][34] creased to the same values as in the 1st methanogenic stage except for butyrate and caproate ( Fig. 3; Table 3).…”

A thermostable mannitol‐1‐phosphate dehydrogenase is required in mannitol metabolism of the thermophilic acetogenic bacterium Thermoanaerobacter kivui

“…Utilization of the sugar alcohol mannitol is also widespread among acetogenic microorganisms. Among 47 acetogens, eight have been reported to use the sugar alcohol mannitol as sole substrate for growth and energy conservation -Acetonema longum (Kane and Breznak, 1991), Blautia coccoides (Kaneuchi et al, 1976), Blautia producta (Lorowitz and Bryant, 1984), Clostridium drakei and Clostridium carboxidivorans (Liou et al, 2005), Eubacterium limosum (Genthner et al, 1981), Sporomusa aerivorans (Boga et al, 2003), Sporomusa termitida (Breznak et al, 1988), while poor growth has been reported for the carboxydotroph Clostridium formiaceticum (Braun et al, 1981). The genes and enzymes important for mannitol utilization, however, have not been elucidated in detail in these acetogens.…”

Competition between reductive acetogenesis and methanogenesis in the pig large‐intestinal flora

“…A major question is the competitiveness of intestinal acetogenic bacteria with other H, consumers, particularly methanogens. In the rumen, methanogens actively appear to out-compete acetogens although acetogens have been isolated from sheep fed high molasses diets (Genthner et al 1981) and from a steer fed a typical high forage diet (Greening and Leedle 1989), and acidogens that used CO, and H, were found in large numbers (Leedle and Greening 1988). Their significance as H, utilizers, however, has never been established.…”