Survey of urease activity in ruminal bacteria isolated from domestic and wild ruminants

A total of 909 strains, including Selenomonas ruminantium, Lactobacillus sp., Enterococcus sp. and Staphylococcus sp., from the rumen of 104 domestic and wild ruminants was used in tests for urease activity. Tests showed that 56.7% of S. ruminantium strains and 18.5% of lactobacilli manifested medium urease activity with mean values of 14.4 +/- 2.5 and 13.85 +/- 0.25 nkat ml-1, respectively. Most of the Enterococcus faecium (62.2%) and all of the E. faecalis isolates expressed urease activity with mean values of 3.9 +/- 0.05 and 4.1 +/- 0.06 nkat ml-1. E. malodoratus, E. solitarius, E. mundtii, Streptococcus bovis and S. uberis did not produce any urease. All the staphylococci screened were urease-producing strains, mostly with medium or low urease activity. The highest level of urease was measured in the rumen epithelial wall of isolates SE30 (19.7 +/- 2.71 nkat ml-1 of rumen content), SCU32 (29.3 +/- 1.6 nkat ml-1) and also in the rumen content isolates EF35 (19.9 +/- 0.94 nkat ml-1) and S. ruminantium 77 (25.35 nkat ml-1). This survey contributes new data to existing information relating to the ureolytic microbial ecosystem in ruminants.