Effects of core soil microbial taxa on soil carbon source utilization under different long-term fertilization treatments in Ultisol

Characterizing the ecological roles of core soil microbial species in soil carbon metabolism is critically important for enhancing carbon sequestration in agricultural systems; however, no studies to date have determined the effects of core soil microbial taxa on carbon metabolism under various long-term fertilization practices. Here, we collected soil samples from field plots that had been subjected to different fertilization practices for nearly 30 years and examined the long-term effects of fertilization on the preferences of core soil bacterial taxa for different carbon sources. We also examined the relative contribution of core soil bacterial taxa in utilization of different carbon source types in Biolog Eco microplates. Long-term fertilization treatment had a significant effect on soil properties and bacterial community structure. The core taxa were closely related to soil carbon source utilization. The co-occurrence network showed that the major ecological clusters containing core taxa made key contributions to soil carbon source utilization. The organic fertilization increased the abundance of a core cluster with a low weighted average rrn copy number. This ecological cluster was the most important factor affecting soil carbon source utilization even among soil physicochemical factors considered. Our findings indicate that core taxa characterized by oligotrophic bacteria have a major effect on carbon source utilization in Ultisols.