Effect of Ligninolytic Axenic and Coculture White-Rot Fungi on Rice Straw Chemical and In Vitro Fermentation Characteristics.

Abstract

The objective of this study was to investigate the axenic culture of Pleurotus ostreatus, Phanerochaete chrysosporium, and the coculture (P. chrysosporium and P. ostreatus) for their potential to break down lignin and to enhance the rumen fermentability of rice straw. Rice straw was fermented by two lignin-degrading fungi, namely, P. ostreatus, P. chrysosporium, and coculture (P. ostreatus and P. chrysosporium) under solid-state fermentation (SSF). The coculture exhibited a mutual intermingling plus inhibition interaction. Coculture treated straw had a lower lignin content (5.26%) compared to P. chrysosporium axenic treated straw (6.18%), although P. ostreatus axenic treated straw was the lowest (3.27%). The polysaccharide content of coculture treated straw was higher than P. chrysosporium axenic treated straw, although smaller than P. ostreatus. P. ostreatus and coculture suitably delignified rice straw without adversely affecting cellulose. Treatment of rice straw with coculture improved in vitro dry matter digestibility (68.08%), total volatile fatty acids (35.27%), and total gas (57.4 ml/200 mg) compared to P. chrysosporium (45.09%, 32.24%, 44.39 ml/200 mg) but was second to P. ostreatus (75.34%, 38.31%, 65.60 ml/200 mg). The coculture via synergistic interaction has the potential to decompose lignin and improve the nutritive value of rice straw than P. chrysosporium.