| Autor: |
Sales-Duval, Muriel, Lucas, François, Blanchart, Gérard |
| Zdroj: |
Anaerobe; August 2001, Vol. 7 Issue: 4 p199-208, 10p |
| Abstrakt: |
This work aims at studying in detail, the interaction between two major bacterial species involved in the ruminal proteolysis, Streptococcus bovisand Prevotella albensis. We chose to investigate this interaction by examining their behaviour both alone in monoculture and together in co-culture on two kinds of protein substrates. Comparison of the behaviour of S. bovisand P. albensisin monoculture, in terms of growth and total proteolytic activity with protein as the sole source of nitrogen, showed that S. bovisgrew more rapidly and developed a higher total proteolytic activity. A higher proportion of short peptides was generated at the end of the exponential growth phase on pea protein medium whereas peptide accumulation did not appear on casein medium for both species; peptides of casein origin would be used more by species in monoculture than those of pea origin. S. bovispredominated in number in both co-cultures but the balance between species was greater on pea proteins (S. bovis: 64% and P. albensis: 36%) than on casein (S. bovis: 86% and P. albensis: 14%). At the same time, the decrease of the proteolytic activity was smaller on pea protein medium than that with casein and the use of proteolysis products was facilitated; peptides liberated by pea protein hydrolysis accumulated less than those obtained from casein. Moreover, the diversity of the endopeptidases expressed increased on pea proteins and the exopeptidase activities remained rather constant whereas they were highly stimulated on casein medium. All the results obtained in co-culture on pea proteins allowed us to suggest that a greater synergism occurred between the two species for the breakdown of proteins. |
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