STUDY OF A CELLULOLYTIC FUNGUS ISOLATED FROM LEAF-LITTER OF Heterostachys ritteriana, A PLANT THAT GROWS IN SALTY ENVIRONMENTS

TOMÁS CAPOZUCCA; MARIO FRANCO; LORENA ELÍADES; GERARDO ROBLEDO; PEDRO BALATTI; MARIO CARLOS NAZARENO SAPARRAT; MARTÍNEZ, M. J.

Madrid

Congreso; II International Congress of Chemical Engineering of ANQUE; 2014

Heterostachys ritteriana (Amaranthaceae) is a halophilic shrub that grows on American saline steppes. In such environments, this plant is the main source of organic matter for the soil improving its capacity to retain water and nutrients, so it might be a biological tool for soil restoration. In this work, we reported the isolation of a fungus from the litter of this plant, collected on an Haplustol soil in Salinas Grandes, Province of Córdoba, Argentina (29º38?30,28??S-51º30?50??W), that degrades cellulose in a salt rich medium and the role that this organism plays in the in-vitro transformation of H. ritteriana litter. A fungus isolated from leaf-litter of H. ritteriana, identified as Fusarium equiseti LPSC 1166 by its morphological characters and sequence of the ITS region of ribosomal DNA, was able to grow on agar plates with sodium-carboxy methyl cellulose as sole C source. This fungus produced a clearing-halo around the colony, suggesting that it secretes cellulose-degrading extracellular enzymes. At salt concentrations over 10% NaCl, both the fungal growth and the cellulolytic activity were reduced. Cultures under solid state fermentation (SSF) conditions using sterile washed litter-leaf material as growth substrate showed that the fungus secreted extracellular β-1,4 endoglucanase activity and produced a significant weight loss of litter biomass after 14 days of incubation (19.2 % compared to uninoculated controls). The pH and chromophore content of the water-soluble fraction from the biotransformed litter material increased at the end of the process. When NaCl concentration in the cultures increased to 10%, the weight loss produced by F. equiseti on the litter material and the β- 1,4 endoglucanase activity were lower, probably because of the deleterious effect of salt on fungal growth and metabolism. Our findings suggest that F. equiseti LPSC 1166 is a halotolerant fungus that can degrade recalcitrant H. ritteriana leaf-litter material in saline soils. In addition, the enzymatic system of this fungus is being studied as a potential robust biocatalyst for plant biomass transformation.