Efeito de fatores abióticos sobre a atividade enzimática de actinobactérias do semiárido

Abstract

Actinobacteria constitute an important microbial group and its enzymatic activity contributes to the structuring of soil communities. In this context, the present study tested the effect of abiotic factors on the growth and amylolytic activity of 18 strains of actinobacteria known to facilitate rhizobia isolated from the soil of the Parque Nacional de Ubajara - PNU, a semiarid region of the Northeast of Brazil. The strains were evaluated for capacity and tolerance to grow in different ranges and concentrations of pH and salinity as well as their amylolytic activity that was tested under the same conditions. It was found that more than 94% of the strains grew at pHs 4 and 9 and approximately 83% tolerated the most saline condition imposed. According to the amylolytic activity, the strains showed enzymatic activity, except at pH 4; linear regression analysis provided a plot showing the highest enzyme production indexes at pH 7 and 2% NaCl concentration. Therefore, the enzymatic activity of these actinobacteria associated with their tolerance to grow under abiotic stress have demonstrated the potential of these bacteria in maintaining the biological processes in the soil, even under conditions of physiological stress, which are typical characteristics of the soils of semiarid regions.