Proteolytic activity of the ruminal bacterium Butyrivibrio fibrisolvens.
AUTOR(ES)
Cotta, M A
RESUMO
The proteolytic activity of Butyrivibrio fibrisolvens, a ubiquitously distributed bacterial species in the gastrointestinal tracts of ruminants and other mammals, was characterized. The relative proteolytic activity (micrograms of azocasein degraded per hour per milligram of protein) varied greatly with the strain: 0 to 1 for strains D1, D16f, E21C, and X6C61; 7 to 15 for strains IL631, NOR37, S2, LM8/1B, and X10C34; and 90 to 590 for strains 12, 49 H17C, CF4c, CF3, CF1B, and R28. The activity levels of the last group of strains were equal to or greater than those found with Bacteroides amylophilus or Bacteroides ruminicola. With the exception of strain R28 activity, 90% or more of the proteolytic activity was associated with the culture fluid and not the cells. Strain 49 produced proteolytic activity constitutively, but the level of activity (units per milligram of protein) was modulated by growth parameters. With various carbohydrates added to the growth medium, the proteolytic activities of strain 49 were positively correlated with the growth rate. However, when the growth rate varied with the use of different nitrogen sources, a similar correlation was not found. The highest activity level was observed with Casamino Acids (1 g/liter), but this level was reduced by ca. 70% with Trypticase (BBL Microbiology Systems, Cockeysville, Md.) or casein (1 g/liter) and by 85% with ammonium chloride (10 mM) as the sole nitrogen source. The addition of ammonium chloride (1 to 10 mM) to media with low levels of Casamino Acids or Trypticase resulted in lower proteolytic activities but not as low as seen when the complex nitrogen sources were increased to high levels (20 g/liter).(ABSTRACT TRUNCATED AT 250 WORDS)
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=203391Documentos Relacionados
- Cloning, sequencing, and expression of a xylanase gene from the anaerobic ruminal bacterium Butyrivibrio fibrisolvens.
- Enzymology of butyrate formation by Butyrivibrio fibrisolvens.
- High-frequency transfer of a naturally occurring chromosomal tetracycline resistance element in the ruminal anaerobe Butyrivibrio fibrisolvens.
- Isolation and characterization of a bacteriocin (Butyrivibriocin AR10) from the ruminal anaerobe Butyrivibrio fibrisolvens AR10: evidence in support of the widespread occurrence of bacteriocin-like activity among ruminal isolates of B. fibrisolvens.
- Characterization of Esterases Produced by a Ruminal Bacterium Identified as Butyrivibrio fibrisolvens1