Biochemical characteristics and in vitro degradability of sunflower seed hull and wheat straw treated with Pleurotus ostreatus and Ganoderma sessile

Abstract

Importance of the work: Exploring sustainable uses for regional agricultural residues can
address the need for eco-friendly solutions in livestock feeding.
Objectives: To evaluate the potential of Pleurotus ostreatus and Ganoderma sessile to
transform sunflower seed hulls (SSH) and wheat straw and to enhance their in vitro digestibility.
Materials and Methods: SSH and wheat straw were treated with Pleurotus ostreatus (strains
A01, PPWarm, P04, P0761, P07) and Ganoderma sessile strain E47. Colonization time, enzyme
activity, phenolic compounds content, reducing sugar content, fiber composition and in vitro
digestibility (IVD) were assessed, along with the impact of the inoculum formulation on these
variables.
Results: Fungal strains colonized substrates within 10–25 d. Laccase activity was in the ranges
2,266–4,621 U/kg in SSH and 1,135–7,279 U/kg in wheat straw. Peroxidase activity was in the
range 0–490 U/kg. In SSH, reducing sugars increased, with G. sessile E47 producing a 164%
increase (p < 0.001). In contrast, in wheat straw, reducing sugars decreased, with P. ostreatus P04
reducing the content by 64% (p < 0.001). The phenolic and triterpenoid contents decreased across
all treatments. Fiber content changes were substrate-dependent—in the SSH, neutral detergent
fiber and acid detergent fiber fractions, increased by 14.1–21.6%, while in the wheat straw, changes
were minimal. IVD remained unchanged for most treatments, except for P. ostreatus PPWarm
(-20.7%, p = 0.013) and G. sessile E47 (-60.9%, p < 0.001) on SSH. Inoculum formulation without
grains altered mycelial effects on substrate degradation, increasing SSH digestibility by 70.5%
(p = 0.003) after treatment with P. ostreatus A01.
Main finding: The fungal treatments modified the SSH and wheat straw composition, with
digestibility improvement critically dependent on inoculum type and substrate.