Duas estirpes de rizóbia isoladas de solos de
várzea da Amazônia Central produziram grandes
quantidades de proteases alcalinas extracelulares,
usando fontes baratas de carbono e nitrogênio. Os
extratos brutos de proteases foram ativos em pH
9,0-11,0. As temperaturas ótimas foram de 35 oC
para a enzima do Rhizobium R-986 e de 55 oC para
a do Bradyrhizobium R-993. As atividades
proteolÃticas aumentaram na presença de 5 mM
dos Ãons Na+, Ca2+, Mg2+ e Mn2+. As proteases
secretadas pelos rizóbios foram fortemente
inibidas por PMSF, um inibidor de serina protease.
As enzimas foram ativas na presença de
surfactantes (SDS e Triton X-100), e estáveis na
presença de agentes oxidantes (H2O2) e redutores
(b-mercaptoetanol) e solventes orgânicos (acetona,
hexano, metanol, 1-propanol e tolueno).
Two rhizobia strains isolated from soils of the Central Amazonian floodplain produced appreciable quantities of
crude alkaline protease extracts with inexpensive carbon and nitrogen sources. These protease crude extracts were
optimally active at pH 9.0-11.0. The optimum temperatures were 35 oC for Rhizobium sp. strain R-986 and 55 oC
for Bradyrhizobium sp. strain R-993. Protease activities in the crude extracts were enhanced in the presence of 5
mM metal ions, such as Na+, Ca2+, Mg2+ and Mn2+. Rhizobia proteases were strongly inhibited by PMSF, a serineprotease
inhibitor. The enzymes were active in the presence of surfactants (SDS and Triton X-100) and stable in
oxidizing (H2O2) and reducing agents (b-mercaptoethanol), and organic solvents (acetone, hexane, methanol, 1-
propanol and toluene).
