Enterobacter cloacae Rs-2 inoculum replaces fertiliser application by half in the field and modifies microbial community structure

Abstract

Using microbial inoculant partial substitution synthetic fertilizer is a new type of environmentally friendly way to significantly improve the corps production and ecological environment. The effects of supplementing Enterobacter cloacae Rs-2 with synthetic fertilizer on the maize growth and soil microbial community diversity in field were investigated in this paper. The optimal fermentation conditions were determined as 5 g·L−1 industrial glucose, 30 g·L−1 industrial peptone, 1 g·L−1 MgSO4 and 0.5 g·L−1 KCl firstly. Field experiment showed that the fresh weight of shoots and roots was increased by 39.69% and 32.46% when half synthetic fertilizer was replaced by microbial inoculant. The soil physical and chemical properties were also greatly improved, especially the contents of available phosphorus, water-soluble calcium and alkali-hydrolyzed nitrogen were significantly increased in T4 (Rs-2 and half chemical fertilizer) and full chemical fertilizer treatment. This result was accompanied by increased the relative abundance of genes related to phospholipid metabolism, phosphotransferase system (PTS) and oxidative phosphorylation metabolism, indicating that Rs-2 may play an important role in the transformation and utilization of phosphorus in soil. The richness, dominance of Proteobacteria, Enterobacteriaceae in the microbial communities were further improved when the microbial inoculant applied. Function prediction PICRUSt analysis indicated that amines and amino acids were the most representative of the total carbon source utilization by the soil microbial communities. It was concluded that the application of 50% of the synthetic fertilizer supplemented with 30 mL microbial inoculant enhanced both the functional diversity of soil microbial communities and maize yield.