Screening of white-rot fungi for bioprocessing of wheat straw into ruminant feed

Abstract

Aim: In this study, the biological variation for improvement of the nutritive value of wheat straw by 12 Ceriporiopsis subvermispora, 10 Pleurotus eryngii and 10 Lentinula edodes strains was assessed. Screening of the best performing strains within each species was made based on the in vitro degradability of fungal-treated wheat straw.

Methods and results: Wheat straw was inoculated with each strain for 7 weeks of solid state fermentation. Weekly samples were evaluated for in vitro gas production (IVGP) in buffered rumen fluid for 72 h. Out of the 32 fungal strains studied, 17 strains showed a significantly higher (P < 0·05) IVGP compared to the control after 7 weeks (227·7 ml g^-1 OM). The three best Ceriporiopsis subvermispora strains showed a mean IVGP of 297·0 ml g^-1 OM, while the three best P. eryngii and L. edodes strains showed a mean IVGP of 257·8 and 291·5 ml g^-1 OM, respectively.

Conclusion: Ceriporiopsis subvermispora strains show an overall high potential to improve the ruminal degradability of wheat straw, followed by L. edodes and P. eryngii strains.

Significance and impact of the study: Large variation exists within and among different fungal species in the valorization of wheat straw, which offers opportunities to improve the fungal genotype by breeding.

Keywords: degradability; different strains/species; in vitro gas production; ruminant; screening; wheat straw; white-rot fungi.