Influence of white-rot fungi on chemical composition and in vitro digestibility of lignocellulosic agro-industrial residues

Abstract

In this work, we tested the ability of white-rot fungi to alter the chemical composition of lignocellulosic agro-industrial residues so that they could be more susceptible to microbial degradation by rumen microorganisms, thus improving in vitro digestibility of neutral detergent fiber. Agro-industrial residues that were incubated for 60 days with Pleurotus ostreatus PLO06 or Lentinula edodes UFV73 showed significant changes in chemical composition, increasing (P<0.05) the crude protein content and the in vitro digestibility of neutral detergent fiber. Lignin content and structural carbohydrates decreased after fungal fructification in most substrates and an increase (P<0.05) in dry matter mineralization was also observed for residues treated with P. ostreatus PLO06. L. edodes UFV73 required a more balanced carbon/nitrogen ratio to grow on lignocellulosic substrates, and P. ostreatus PLO06 was in general, more effective than L. edodes UFV73 to alter the chemical composition and digestibility of the agro- industrial residues. Among the residues tested, eucalyptus bark showed the highest increase in digestibility after fungal growth. The marked increments in fiber digestibility obtained with substrates inoculated with either P. ostreatus PLO06 or L. edodes UFV73 indicate the usefulness of biological pretreatments to improve the nutritive value of low-quality lignocellulosic feedstuffs that could be incorporated into ruminant rations. Key