[B-BG01] Earth and Planetary Science Frontiers for Life and Global Environment

[BBG01-P03] Novel bacterial players driving iron cycle in freshwater sediments

*Shingo Kato¹, Moriya Ohkuma¹ (1.RIKEN-BRC, JCM)

Keywords:iron-oxidizing bacteria, iron-reducing bacteria, cultivation, genomics

Iron cycling (oxidation/reduction and dissolution/precipitation) is involved in geochemical cycling of various elements such as carbon, sulfur, and heavy metals. In natural environments, the iron cycling is mainly driven by iron-oxidizing/reducing microorganisms. Although recent culture-independent metagenomics has suggested the presence of phylogenetically diverse iron-oxidizing/reducing microorganisms, only small number of cultivated species have been reported so far. Here we report isolation of novel iron-oxidizing bacteria (FeOB) and novel iron-reducing bacteria (FeRB) from freshwater iron-rich microbial mats by single-cell sorting or soft-agarose-gradient cultivation. Whole-genome sequences of these bacterial strains were determined by a combination of Illumina and Nanopore sequencing. Remarkably, one of the FeRB isolates was belonging to the phylum Bacteroidetes, of which only a few FeRB have been reported so far. No known genes involved in iron reduction was found in its complete genome. Our results suggest the presence of more diverse FeRB than previously recognized, which has been overlooked by culture-independent molecular methods such as metagenomics.