Howardella ureilytica gen. nov., sp. nov., a Gram-positive, coccoid-shaped bacterium from a sheep rumen

Abstract

In the ruminant herbivore, primary digestion of the food is carried out by the micro-organisms of the rumen. For many of the ruminal bacteria, ammonia is the major nitrogen source. Urea is present in ruminant saliva and diffuses into the rumen through the rumen wall and, as urea is rapidly hydrolysed in the rumen (Pearson & Smith, 1943), it is an important source of ammonia especially in the recycling of nitrogen in the rumen. While urea is physiologically important to nitrogen metabolism in ruminants, it is also economically important to ruminant feeding. However, the microbial aspects of urea metabolism are not well understood, either regarding numbers relative to total rumen bacteria or whether the ureolytic bacteria are widespread in rumen contents, or even whether bacteria are the major source of rumen urease (Farlin et al., 1968).Strain GPC 589 T was isolated from the rumen fluid of a penned cannulated sheep that had been fed on a diet of hay and grass with water ad libitum. The anaerobic culture technique of Hungate (1950) was used with oxygen-free CO 2 as the gas phase and incubation at 37 u C. Initially, a fresh rumen fluid sample (0.5 %, v/v) was enriched for 48 h (Cook, 1976) in medium GM comprising (w/v): Bacto casitone (0.5 %), Bacto yeast extract (0.5 %), KH 2 PO 4 (0.25 %), Na 2 HPO 4 (0.25 %), CH 3 . COONa (0.1 %), mannitol (0.2 %), MgCl 2 . 6H 2 O (0.05 %), sodium thioglycollate (0.075 %) and resazurin (0.0001 %), pH 7.0; autoclaved at 103.5 kPa for 15 min. Filter-sterilized urea (0.2 % w/v, final concentration) was added to cooled medium. The enrichment was maintained by overnight subculturing (0.1 ml) in 8 ml medium G (mannitol-free GM) in Hungate tubes. An ureolytic Gram-positive coccus Abbreviation: ECL, equivalent chain-length.

Alkalizing Reactions Streamline Cellular Metabolism in Acidogenic Microorganisms

“…In several bacterial species, such as Ureaplasma urealyticum [11], Bacillus pasteurii [12], Helicobacter pylori [13] and Howardella ureilytica [14], urea hydrolysis generates an ammonium/urea-dependent chemical potential that is coupled to ATP synthesis. The addition of 10 mM urea to a suspension of nutrient-starved S. thermophilus cells resulted in a rapid increase in the intracellular ATP concentration and a concomitant extracellular and intracellular alkalisation that was caused by increased urease activity (Figure 1A).…”

Changes in the Solid-, Liquid-, and Epithelium-Associated Bacterial Communities in the Rumen of Hu Lambs in Response to Dietary Urea Supplementation

“…Howardella spp. are reported to have strong ureolytic activity and to possibly play roles in urea hydrolysis (Cook et al, 2007). Desulfobulbus spp.…”

Does intra-ruminal nitrogen recycling waste valuable resources? A review of major players and their manipulation

“… X X [ 47 , 69 ] Eubacterium budayi X [ 27 ] Eubacterium pyruvativorans X [ 82 ] Eubacterium ruminantium X [ 53 ] Fibrobacter succinogenes X [ 53 ] Fusobacterium sp. X [ 26 ] Howardella ureilytica X [ 91 ] Klebsiella aerogenes X [ 88 ] Lachnospira multipara X X [ 49 , 53 ] Lactobacillus casei var. casei X [ 88 ] Micrococcus varians X [ 89 ] Megasphaera elsdenii X X [ 53 ] Peptostreptococcus anaerobius X [ 77 ] Prevotella sp.…”