Initial studies on trehalase activity from peanut rhizobia

DARDANELLI MARTA; GONZÁLEZ PAOLA S.; BUENO MIGUEL; GHITTONI NORA

Pucón (Chile)

Congreso; . VIII Congreso de la Asociación Panamericana de Bioquímica y Biología Molecular (PAABMB); 1996

Asociación Panamericana de Bioquímica y Biología Molecular

Recently (Ghittoni & Bueno 1996) we reported trehalose accumulation in four peanut rhizobia cultured under hypersalinity, and we also communicated (SAIB 95) increased activity of trehalose-P- synthetase in those bacteria. The activity of the catabolic enzyme trehalasa was only detected in some Rhizobium  strains (Hoelzle & Streeter 1990). In the present work, we studied trehalase activity from peanut inoculants recommended by international collections. Bacteria were cultured  as described elsewhere (Ghittoni & Bueno 1995). Trehalase activity was determined by the method of Muller et al, (1992) with some modifications. After subjecting the cells to chloroform shock (Ames et al 1984) the released activity of trehalase was 9- fold greater than the cellular activity before shock, result indicative of a periplasmic localization. Crude periplasmic trehalase manifested a pH optimun between 6.4 and 7.0, and a temperature optimun at approximately 60 C. During 24 hs of bacterial growth in basal medium, changes in trehalase activiy were not detected. On the other hand, in bacteria grown under hypersalinity for 24 hs, trehalase activity diminished to 47%  of control values. This preliminary result suggests that decreased degradation of trehalose could be one of the responsible factors for the disaccharide accumulation in peanut rhizobia under hypersaline stress.