Project description:Iron is limiting in the environment, bacteria respond to this deprivation by activating genes required for bacterial iron homeostasis. Transcriptional regulation in response to iron in Gram-negative bacteria is largely mediated by the ferric uptake regulator protein Fur, which in the presence of iron binds to a specific sequence in the promoter regions of genes under its control and acts as a repressor. Here we describe comparative global gene expression analysis using DNA microarray based on the whole genome sequence of the magnetotactic bacterium Magnetospirillum magneticum AMB-1 was conducted between wild type strain and a non-magnetic NMA61 mutant strain, generated by mini-Tn5 transposon mutagenesis which is incapable of assimilating iron to cytoplasm. No induction of the fur genes in NMA61 mutant strain was considered to be due to low intracellular iron concentration. In the iron-replete condition, among 4492 genes, 434 genes were down-regulated and 527 genes were up-regulated in the wild type strain. Among 434 genes down-regulated, 299 genes were not down-regulated in NMA61 mutant strain, indicating these genes are candidates of Fur-regulated. Keywords: Iron, magnetotactic bacteria
Project description:Methanogens inhabit euxinic (sulfide-rich) or ferruginous (iron-rich) environments that promote the precipitation of transition metals as metal sulfides, such as pyrite, reducing metal or sulfur availability. Such environments have been common throughout Earth’s history raising the question as to how anaerobes obtain(ed) these elements for the synthesis of enzyme cofactors. Here, we show a methanogen can synthesize molybdenum nitrogenase metallocofactors from pyrite as the source of iron and sulfur, enabling nitrogen fixation. Pyrite-grown, nitrogen-fixing cells grow faster and require 25-fold less molybdenum than cells grown under euxinic conditions. Growth yields are 3 to 8 times higher in cultures grown under ferruginous relative to euxinic conditions. Physiological, transcriptomic, and geochemical data indicate these observations are due to sulfide-promoted metal limitation, in particular molybdenum. These findings suggest that molybdenum nitrogenase may have originated in a ferruginous environment that titrated sulfide to form pyrite, facilitating the availability of sufficient iron, sulfur, and molybdenum for cofactor biosynthesis.
2023-05-01 | GSE216895 | GEO
Project description:Metagenomics of magnetotactic bacteria from Dianchi Lake
| PRJEB8080 | ENA
Project description:Magnetotactic bacteria of Bailonghu, Yaoquanhu, Yueyaopao (Wudalianchi, China)