Interactive Effects of Acidity and Aluminium on the Growth, Lipopolysaccharide and Glutathione Contents in Two Nodulating Peanut Rhizobia

LORENA PONSONE; ADRIANA FABRA; STELLA CASTRO

SYMBIOSIS

Balaban

Año: 2004 vol. 36 p. 193 - 204

0334-5114

Abstract Aluminium (A13+) is an abundant element in the soil, occurring in a wide variety of mineral forms which are largely inert at neutral pH. As the soil pH decreases, aluminium is mobilized into the soil solution and may become toxic to plants and soil microorganisms. In this work we show the effect of the combination of acidity and aluminium on two nodulating peanut rhizobia: Bradyrhjzobjum sp. SEMIA 6144, peanut recommended inoculation, and the native isolate NCHAX obtained from soil Córdoba (Argentina). Bradyrhjzobjum sp. showed a decrease in the growth rate and an increase of glutathione (GSH) content at pH 5.5 and 50 pM aluminium. Although the increase of the GSH content was not enough to prevent the bacterial growth rate decrease, the high level found could be related with a protection against the toxic effects of this metal. The isolate NCHAX growth rate and viability were not affected by the acid pH and the aluminium and the GSH content remained unchanged. However, in both peanut microsymbionts changes were found in the lipopoly- saccharide (LPS) contents related to alteration in the cellular hydrophobicity under this stress condition.   Keywords: Rhizobia, peanut, A13+ , LPS, cellular hydrophobicity , GSH