The composting microbiome and a multifunctional Bacillus tequilensis JZF3 with straw degradation and pathogen...

Aerobic composting is a sustainable approach for converting organic waste into bio-fertilizer, where microorganisms play a central role in the degradation of recalcitrant lignocellulose. This study employed high-throughput sequencing to analyze the dynamic changes in bacterial and fungal communities during composting using distillers' grains, oil cake and cattle manure as raw materials. The results revealed pronounced successional changes in both microbial community structure and predicted function over time. Specifically, Firmicutes and Ascomycota were the dominant bacterial and fungal phyla, respectively, with the genus Bacillus maintaining high abundance throughout the process. The predicted functional profile indicated a shift in bacterial functions from initial xenobiotic biodegradation to core metabolic processes (such as energy and carbohydrate metabolism) in later stages. A total of 97 bacterial strains belonging to 38 species were isolated from different composting samples, with four strains (Bacillus licheniformis JZF8, B. altitudinis JZF2, B. tequilensis JZF3, and B. siamensis FJ3-3) showing strong cellulase, ligninase and protease activities. Among them, strain JZF3 not only exhibited these enzymatic activities and significant antagonistic activity against plant pathogens, but also was a dominant culturable species within the compost community. Furthermore, strain JZF3 was able to directly degrade rice straw without chemical pretreatment, achieving a degradation rate of 22.5%. The resulting degradation products also significantly promoted the growth of tobacco seedlings. This study identifies B. tequilensis JZF3 as a multifunctional agent that combines straw degradation with pathogen suppression and plant growth promotion, offering a novel strategy for synergizing agricultural waste recycling with disease control.