Synthetic bacterial communities reshape microbial communities and enhance nutrient supply in desertified land of Northwest China

Climate change and human disturbance have led to widespread soil degradation worldwide. The problem of desertification is gradually destroying soil carbon accumulation. Synthetic bacterial communities (SynComs) are a healthy solution capable of improving the microbiome for plant growth. However, the effect of SynCom on nutrient functions in desertified land remains poorly understood. Here, two years of different treatments (control, chemical fertilizer, SynCom, combined SynCom-Chemical fertilizer) were conducted on desertified land in the Loess Plateau, and we aimed to reveal the effects of introducing SynCom on bacterial communities and nutrient multifunctionality. The SynCom enriched more beneficial bacteria as key microorganisms and increased biodiversity. At the same time, the bacterial community structure of the desertified land shifted significantly and remained stable at the soil surface (0–10 cm). We found that SynCom enhanced the complexity of the bacterial network with higher modularity. Our results also revealed the influence of biotic and abiotic factors on nutrient availability. Bacterial diversity and soil electrical conductivity (EC) were the significant influencing factors for chemical and combined fertilizers. However, SynCom exhibited stronger bacterial effects, and soil organic matter significantly affected the biodiversity-ecosystem function (BEF) relationships. Overall, this study illustrates the impact of microbial amendment on nutrient function in desertified land and provides insights into SynCom application to enhance ecosystem restoration and carbon sinks.