Catalyzes the reversible oxidative deamination of glutamate to alpha-ketoglutarate and ammonia. P.ruminicola possess both NADP(H)- and NAD(H)-dependent activities on the same enzyme, suggesting that both anabolic and catabolic forms of the enzyme might occur. H2O + L-glutamate + NAD(+) = 2-oxoglutarate + H(+) + NADH + NH4(+) H2O + L-glutamate + NADP(+) = 2-oxoglutarate + H(+) + NADPH + NH4(+) Homohexamer. Belongs to the Glu/Leu/Phe/Val dehydrogenases family.