title: Are ruminal bacteria protected against environmental stress by plant antioxidants?
abstract: OBJECTIVE
  To investigate the activity response of the antioxidant enzymes superoxide dismutase (SOD) and glutathione peroxidase (GSHPx) of the rumen bacterium Streptococcus bovis following exposure to mercury(II) chloride (HgCl(2) in the presence of plant antioxidants.
  
  
  RESULTS
  Streptococcus bovis was grown with 0 or 5 microg ml(-1) of HgCl(2) alone or together with antioxidant substances (AOS): seleno-l-methionine (Se), alpha-tocopherol (alpha toc), beta-carotene (beta car), melatonin (mel). The activities of SOD and GHPx were estimated in supernatants of disrupted bacterial cells. A significant decrease in the Strep. bovis SOD activity in the presence of HgCl(2) and tested AOS, except mel, was observed. The GSHPx activity of Strep. bovis was under the same cultivation conditions nonsignificantly changed and a significant decrease in the GSHPx activity was recorded only in the presence of beta car.
  
  
  CONCLUSIONS
  The positive effect of Se, alpha toc and beta car on the elimination of environmental stress, evoked by mercury, in ruminal bacterium Strep. bovis in vitro was documented.
  
  
  CONCLUSIONS
  The potential role of plant antioxidants in elimination of the environmental stress of ruminal bacteria evoked by heavy metals is discussed.
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D002417:Cattle; D005979:Glutathione Peroxidase / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects*; D010944:Plants / Q000737:chemistry*; D017382:Reactive Oxygen Species / Q000378:metabolism; D012417:Rumen / Q000382:microbiology*; D016985:Streptococcus bovis / Q000187:drug effects* / Q000378:metabolism; D013482:Superoxide Dismutase / Q000378:metabolism*
chemical_list: D000975:Antioxidants; D017382:Reactive Oxygen Species; D005979:Glutathione Peroxidase; D013482:Superoxide Dismutase