Phylogenetic diversity contributes more to sediment magnetism than abundance during incubation of iron-reducing sediment from a non-active volcanic lake in Northeast China

Aim This study aimed to analyse bacterial community and biomineralization products from Wudalianchi non-active volcanic field and the relationship between magnetization and bacterial community. Methods and Results Eighteen sediment samples obtained from Wenbo Lake, high-throughput sequencing and quantitative PCR (qPCR) were separately employed to investigate the bacterial community composition dynamics and abundance variation of the sediment sample with the highest iron-reducing capacity during incubation. The mineralization products were characterized by transmission electron microscopy, scanning electron microscopy, X-ray diffraction (XRD), Raman spectroscopy, vibrating sample magnetometer (VSM) and variable-temperature magnetism analyses. The results showed that the highest iron reduction rate was 98 center dot 06%. Seven phyla were identified as dominant bacterial phyla during the incubation process. Iron-reducing bacteria (FeRB) including Geobacter, Desulfosporosinus and Clostridium were involved in the iron mineralization process. The 16S rDNA copy numbers of sediment decreased quickly and then stayed steady during the incubation. Bacteria with rod-shaped and spheroid species were involved in extracellular iron reduction to produce magnetic particles with massive aggregation and columnar structures on the mineral surface morphologies. The materials produced by the microbial community over the incubation period were sequentially identified as siderite, magnetite and maghemite. The magnetism of the mineral samples gradually increased from 0 center dot 31748 to 33 center dot 58423 emu g(-1) with increased incubation time. The final products showed relatively stable magnetism under 0-400 K. Meanwhile, the saturation magnetization (M-S) of the mineralized substance was tightly associated with bacterial diversity (P < 0 center dot 05). Conclusions Bacterial community varied during incubation of iron-reducing sediment of volcanic lake. Various iron mineral crystals were in turn formed extracellularly by FeRB. The magnetism of mineralized products was tightly associated with bacterial community. Significance and Impact of the Study These results not only help us to better understand the iron mineralization of FeRB in the volcanic lake sediments but also provide basic information for the future application of FeRB in environmental bioremediation.