Optimizing fungal treatment of lignocellulosic agro-industrial by-products to enhance their nutritional value

Abstract

This study delves into the dynamic interaction between various fungal strains, substrates, and treatment durations to optimize the nutritional value of these by-products. Six fungi, including Penicillium chrysogenum, Fusarium sp., Fusarium oxysporum, Fusarium solani, Penicillium crustosum, and Cosmospora viridescens, were evaluated across three substrates: wheat straw (WS), cedar sawdust (CW), and olive pomace (OP) over treatment periods of 4, 8, and 12 weeks. The study discerned profound impacts of these fungi across multiple parameters, including cellulose variation (C.var), lignin variation (L.var), and in vitro true digestibility variation (IVTD.var). Our results demonstrated that the various fungi had a significant effect on all parameters (p < .001). Noteworthy, F. oxysporum and F. solani emerged as exemplars, displaying notable lignin degradation, cellulose liberation, and IVTD enhancement. Importantly, P. crustosum demonstrated substantial cellulose degradation, exhibiting optimal efficacy in just 4 weeks for all substrates. Notably, F. sp. excelled, yielding favorable results when treating WS. P. chrysogenum achieved optimal outcomes with 8-week treatment for WS. Both Fusarium sp. and P. chrysogenum exhibited slight cellulose release, with remarkable reduction of WS lignin compared to other substrates. Especially, WS and OP displayed superior digestibility enhancements relative to CW. It should be noted that the treatment duration further shaped these outcomes, as prolonged treatment (12 weeks) fostered greater benefits in lignin degradation and digestibility, albeit with concomitant cellulose degradation. These findings underscore the intricate balance between fungal strains, substrates, and treatment durations in optimizing the nutritional value of lignocellulosic agro-industrial by-products. The outcomes of this study lead to the enhancement in the overall value of by-products, promoting sustainable livestock feed and advancing agricultural sustainability.

Keywords: cellulose; digestibility; fungal treatment; lignin; lignocellulosics; nutritional value; ruminant feed; sustainable agriculture.

FIGURE 1

Evolution of fibers (C.var and L.var) and digestibility (IVTD.var) after treatment of substrates (CW, cedar wood; OP, olive pomace; WS, wheat straw) by fungi for 4, 8, and 12 weeks.

FIGURE 2

Visualizing the effectiveness of fungal treatment on the treated substrate over time using an alluvial diagram with positive observations. (a) Visualization of C.var; (b) visualization of L.var; and (c) visualization of IVTD.var. CW, cedar wood sawdust; F, frequency of observation; OP, Olive pomace; WS, wheat straw.

FIGURE 3

Clustergram of fungal treatment effects on different substrates over varied durations.

FIGURE 4

Changes in the NFC/NDF ratio and crude protein content of lignocellulosic substrates (CW, cedar wood sawdust; OP, olive pomace; WS, wheat straw) treated by various fungal strains (F. solani, F. oxysporum, F. sp., P. chrysogenum, P. crustosum, and C. viridescens) over a 12‐week duration. ^abcDifference in superscripts in the same substrate indicates significance at p < .05.

FIGURE 5

Principal component analysis (PCA). (a) Variables factor map (PCA); (b) Individuals factor map (PCA); (d) Qualitative factor map (PCA); and (c) Ascending Hierarchical Classification of the individuals. The labeled factors, variables, and individuals are those the best shown on the plane.

FIGURE 6

The Pearson correlation between parameters. C, Cellulose; C.var, cellulose variation; IVTD, in vitro true digestibility; L.var, lignin variation.