Screening and combination selection of multifunctional actinomycetes for aerobic composting

ABSTRACT To screen the most effective combination of multipurpose actinomycete strains for aerobic composting, lignocellulose-degrading strains were obtained through enrichment culture, separation and purification, and multiselection culture. The isolated strains were identified on the basis of morphology and 16S rRNA gene sequencing and comparison. The obtained actinomycetes were screened for the lignocellulose degradation rate, ammonia and hydrogen sulfide removal rate, and cellulase activity. Subsequently, a combination of strains with ecological coordination and complementary functions was determined through antagonistic tests. The combined strains were subjected to a straw fermentation test to evaluate their degradation effect. As a result, 20 strains of actinomycetes were isolated and identified from more than 56 samples from different sources, including 18 strains of Streptomyces sp. and 2 strains of Nocardiopsis sp. After a number of screenings, eight strains of actinomycetes with strong function were obtained. From the results of function and antagonistic tests, strains A3, A7, A8, A11, and A16 were selected to form consortia. The straw fermentation test showed that the lignocellulose degradation rate of the strain combination was as high as 39.8%, which was significantly higher than that of eachevery single strain ( P < 0.05). The screened multifunctional actinomycete strains and their combination enriched the actinomycete germplasm resources used for microbial enhanced aerobic composting. IMPORTANCE With the development of animal husbandry in China, the production of a large amount of livestock and poultry manure has become one of the main agricultural pollution sources. High-temperature aerobic composting stands out as one of the most crucial methods for the safe and resourceful utilization of livestock and poultry manure, serving as an essential link between crop cultivation, animal breeding, and sustainable agricultural development. Numerous studies have demonstrated that the addition of exogenous multifunctional bacterial agents to compost reduces not only harmful emissions but also sequesters or increases essential nutrients. However, these efficacies depend on the specific functions of the bacteriophage itself, the harmonization and complementarity within the colony, and its ability to adapt to the environment. In recent years, relatively few studies have been conducted on actinomycetes. This experiment provides excellent actinomycete resources for the production of high-efficiency and high-quality compost compound microbial agents of manure and straw.