The Influence of Lectins from Azospirillum brasilense Sp7 and Azospirillum lipoferum 59b on the Activity of Plant β-Glucosidase

Abstract

Previous work from this Lab has shown that the proteins, lectins detected on the surfaces of the associative nitrogen-fixing soil bacteria Azospirillum brasilense Sp7 and Azospirillum lipoferum 59b come into play in interaction with plants at the early stages of establishment of an associative system (Nikitina V.E. et al., 1996). The present work demonstrates the influence of the lectins from A. brasilense Sp7 and A. lipoferum 59b on the activity of β-glucosidase of sweet almonds. Bacteria were grown on synthetic medium (Sadasivan L. et al., 1985) at 37 °C for 18 hours. Agglutinating activity of the cells was estimated with the help of the reaction of hemagglutination, with the use of rabbit erythrocytes treated with trypsin (Lis H. et al., 1972). Isolation of lectins from the cell surface was carried out in accordance with Eshdat (Eshdat Y. et al., 1978). The activity of β-glucosidase was evaluated spectrophotometrically at 425 nm by the amount of the formed nitrophenol (Buglova T.T. et al., 1991). It has been demonstrated that the addition of the increasing concentrations of lectins from A. brasilense Sp7 and A. lipoferum 59b caused the decrease of enzyme activity, hence exerts the inhibiting effect. Maximum inhibiting effect for the lectin from A. brasilense Sp7 was observed at the concentration of 70 mkg/ml (in this case enzyme activity decreased to 85%). The inhibiting effect of the lectin from A. lipoferum 59b was better pronounced (the enzyme activity decreased to 11%) and exhibited at reasonably lower concentrations, namely, 0.32; 0.64; 1.28 mkg/ml.