The role of microbial inoculum in improving composting performance and promoting compost maturation: A review

Accelerating the composting of organic waste remains a key objective in research and practice. This review aims to critically examine recent advancements in microbial inoculation (MI) strategies and their role in enhancing composting performance and promoting compost maturation. It synthesizes findings on microbial inocula, including single strains and consortia, and their effects on composting phases, microbial succession, and metabolic functions. It discusses the influence of MI on physicochemical parameters, such as moisture content, pH, temperature, and nutrient balance, and the impact on compost stability and humification. It addresses the impact of microplastics on microbial communities in composting, highlighting how microplastics can alter microbial dynamics and affect compost quality. The MI improves the efficiency of organic matter decomposition, shortens the time, enhances pathogen suppression, and produces higher-quality compost. Inoculations encourage enzyme synthesis, accelerate the breakdown of organic matter, elevate temperatures, boost humification, and enhance compost maturity. This review highlights the importance of MI in enhancing organic waste biotransformation, thereby contributing to sustainable waste management and resource recovery. It identifies research gaps and suggests future research directions, including large-scale inoculation trials, economic feasibility assessments, and the development of standardized microbial dosing protocols to support industrial and municipal composting systems. • Inoculants enhance decomposition, pathogen suppression, and compost quality. • Microbial augmentation accelerates degradation, producing stable and mature compost. • Optimizing inoculants and mitigating microplastic effects ensures compost viability. • Effective microbial strain selection and application methods remain underexplored. • Lack of studies on microplastic effects on microbial activity and compost quality.