Photodegradation of Soil Organic Matter and its Effect on Gram (-) Bacterial Growth.

GABRIELA N. BOSIO; PEDRO DAVID GARA; FERNANDO S. GARCÍA EINSCHLAG; MÓNICA C. GONZALEZ; MARÍA T. DEL PANNO; DANIEL O. MÁRTIRE

PHOTOCHEMISTRY AND PHOTOBIOLOGY

Año: 2007

0031-8655

To learn more about the role of the reactive oxygen species (ROS) in the production of bioavailable products of the dissolved organic matter, we investigate here the effect of the photolysis (lexc > 320 nm) of a soil extract (SE), on the growth of bacteria isolated from the same soil as used for obtaining the extract. Comparative experiments with Aldrich humic acid (AHA) as substrate were performed. The photodegradation of the SE was evaluated with different techniques: uv-visible absorption spectroscopy, fluorescence excitation emission matrixes, and Fourier transform infrared spectroscopy. Known ROS scavengers were employed to study the effect of photochemically produced ROS on the photodegradation of the substrates. To evaluate the effect of irradiation on the bioavailability of the SE and AHA, photolyzed and non-photolyzed substrates were added to differents culture media and the growth of Pseudomonas sp. isolated from the soil and a strain of Escherichia coli were studied. The different results obtained were assigned to the dissimilar metabolisms of both bacteria.