Influence of pH and temperature on amylolytic activity of rhizobia isolated from Amazonian soils

Information is scarce regarding the enzymatic profiles of rhizobia bacteria. On solid medium, a 7 x 3 x 3 factorial experiment was conducted to evaluate the effect of pH (5.0, 6.5 and 8.0) and temperature (25, 35 and 42 ºC) on amylase activities of seven rhizobia strains. The highest enzymatic activities were found in acid environments, with some bacteria also producing significant levels at pH 8.0. Among the significant interactions (P<0.01), INPA strains R-110 and R-822 exhibited maximum activities at pH 5.0 and 25 ºC, with the R-822 being also a good amylase producer at 35 and 42 ºC. In general terms, INPA strains R-110 and R-822 were the best enzyme producers, with amylolytic enzymatic activities higher than 2.0.

Extracellular amylases; solid medium; pH; temperature

Instituto Nacional de Pesquisas da Amazônia Av. André Araujo, 2936 Aleixo, 69060-001 Manaus AM Brasil, Tel.: +55 92 3643-3030, Fax: +55 92 643-3223 - Manaus - AM - Brazil