Glutamine synthetase and protease enzyme activities and growth response ofruminal bacterium Prevotella ruminicola strain B(1)4 to nitrogen source and concentration

The objective of this study was to determine the effects of varying nitroge n sources and concentrations upon glutamine synthetase and protease activit ies in Prevotella ruminicola strain B(1)4. Based on growth response it appe ars that ammonium chloride or pepticase limited P. ruminicola becomes nitro gen limited when nitrogen concentration is at 0.5 mM. However, when casein was provided as the sole source of nitrogen P. ruminicola becomes nitrogen limited at 2.5 mM. Glutamine synthetase activity was measured from mid-log phase cells grown in either nitrogen-limited or non-limited conditions. No activity was detectable in the nonlimited treatments. However, in the N-lim ited treatments, pepticase had the highest activity (20.76 units), followed by ammonium chloride (18.72 units) and casein (14.42 units). Protease acti vity assays indicated that nitrogen-limited cultures had higher proteolytic activity than non-limited cultures. Moreover, these activities appeared to follow the same response pattern as the previously observed glutamine synt hetase activities. The results of this study indicate that B. ruminicola st rain B(1)4 protease activity may be influenced by nitrogen concentration su ch that activity increases when nitrogen availability decreases.