Abstract

OLIVEIRA, Arlem Nascimento de; OLIVEIRA, Luiz Antonio de  and  ANDRADE, Jerusa Souza. Partial characterization of amylases of two indigenous Central Amazonian rhizobia strains. Braz. arch. biol. technol. [online]. 2010, vol.53, n.1, pp. 35-45. ISSN 1516-8913.  http://dx.doi.org/10.1590/S1516-89132010000100005.

Amylase production and partial characterization of crude enzyme preparations from two rhizobia strains (R-926 and R-991) were evaluated. For both the strains, maximal amylase activities were achieved during the early-to-mid- exponential growth phase; both were active over a pH range from 4.5 to 8.5 and temperature from 30 to 50 ºC. None of the ions studied (K⁺, Na⁺, Ca²⁺, Hg²⁺, Mg²⁺, Mn²⁺, Cu²⁺ and Zn²⁺) was required for the catalytic activity of strain R-926; amylase activity of strain R-991 was stimulated in the presence of K⁺, Hg²⁺ and Zn²⁺. The surfactants SDS, Triton X-100 and Tween-80 did not have a pronounced inhibitory effect on enzyme activities; SDS and Tween-80 caused the highest stimulatory effects. Amylase activities from the rhizobia strains were reduced by up to 30% in the presence of EDTA; amylase activity of R-926 was also inhibited by HgCl₂, suggesting that Ca²⁺and cysteine residues could be important for activity of this strain.

Keywords : Rhizobium; Bradyrhizobium; Amylase production; Enzymatic properties.