Succession of metabolically active Anaeromyxobacter community in flooded paddy soil owing to organic carbon input

Anaeromyxobacter spp. are prevalent and can make important contribution to microbial Fe(III) reduction in flooded paddy soils, which could be greatly regulated by exogenous organic C input. In this study, dynamics in the abundance and structure of metabolically active Anaeromyxobacter community based on RNA level were investigated by a 40-d anaerobic incubation of paddy soils amended with glucose at 0.1 and 0.5 mol C kg(-1) soil, respectively. Compared with the control treatment, glucose additions generally showed obvious inhibitory effect on the Anaeromyxobacter growth; glucose addition at low concentration decreased the abundance of Anaeromyxobacter by 3.56 x 10(6) to 4.06 x 10(7) copies g(-1) soil within the first 5 d of incubation, whereas a remarkable decrease by 4.54 x 10(6) to 7.71 x 10(7) copies g(-1) soil occurred after paddy soils were amended with high glucose concentration. Anaeromyxobacter dehalogenans-like OTU_1 (where OTU stands for operational taxonomic unit) was dominant in the metabolically active Anaeromyxobacter community and showed significant and positive relationship with Fe(III) reduction process. The structure of Anaeromyxobacter community was greatly altered by glucose additions, and divergences mainly occurred after 5 d of incubation. Additionally, glucose additions could enhance interactions within the Anaeromyxobacter community, especially for positive correlations. In general, glucose addition could greatly inhibit the abundance and alter the structure of Anaeromyxobacter community by jointly decreasing soil pH; however, it could promote the final Fe(III) reduction by enhancing the utilization of Anaeromyxobacter to crystalline Fe oxide.