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

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 .