Effects of phosphate-solubilizing bacteria on phosphorus components, humus and bacterial community metabolism during spent mushroom substrate composting

To address the low conversion of effective phosphorus during previous studies on spent mushroom substrate (SMS) composting, phosphorus-solubilizing bacteria (PSB) were utilized to increase the effective phosphorus content in this study. The results demonstrated that PSB treatments exhibited higher temperature levels up to 66 °C. The TN, NH4+-N, and NO3−-N contents were higher than those of the control treatment (CK) by 9.01%, 50.01%, and 4.61%, respectively. Inoculation with PSB increased effective phosphorus, total phosphorus, and humus content in the SMS compost by 6.84%, 11.05%, and 9.10%. In addition, based on PICRUSt analysis, inoculation with PSB significantly promoted metabolic pathways associated with phosphorus conversion or the production of substances that can facilitate phosphorus conversion or phosphorus leaching, thus improving phosphorus utilization in compost. In conclusion, the addition of PSB can improve the bioavailability of P and the humus content in SMS compost to realize the green and sustainable development of the edible mushroom industry.