Bioconversion of Lignocellulosic Agricultural Residues: Omics-Based Development of Microbial Biopreparations for Sustainable Waste Management

The increasing volume of plant-based waste generated by the agri-food sector represents both an environmental challenge and an underexploited biotechnological resource. These wastes, rich in lignocellulosic compounds, constitute a natural habitat for specialized microorganisms. The aim of this article is to provide a critical review of the potential use of such wastes—specifically straw, pomace, and manure—in two complementary ways: (1) as a specific source for isolating new microbial strains with high biodegradation capacity and plant-growth-promoting potential, and (2) as a low-cost substrate for their propagation, e.g., in solid-state fermentation processes. This dual perspective represents a novel, integrative approach, as previous reviews typically address these aspects in isolation rather than considering their synergistic potential. The article discusses the relationship between the chemical composition of selected wastes (straw, pomace, manure) and the targeted selection of desirable microbiological traits. Particular emphasis is placed on advanced, integrated approaches for assessing microbial potential, combining phenotyping (zymography, activity assays), genomics (whole-genome sequencing—WGS, identification of CAZyme genes and biosynthetic gene clusters), and metabolomics (metabolite profiling, 3D MSI imaging). The limitations of individual methods are critically evaluated, and key research gaps are identified, including the need for in situ validation of omics-based findings and the development of stable microbial consortia with predictable performance under variable environmental conditions. These gaps are discussed in the broader context of circular bioeconomy and sustainable agriculture, highlighting the strategic relevance of integrating waste valorization with microbiome-based biotechnological innovations.