Free Iron and Iron-Reducing Microorganisms in Permafrost and Permafrost-Affected Soils of Northeastern Siberia
- PDF / 1,130,048 Bytes
- 14 Pages / 612 x 792 pts (letter) Page_size
- 78 Downloads / 219 Views
BIOLOGY
Free Iron and Iron-Reducing Microorganisms in Permafrost and Permafrost-Affected Soils of Northeastern Siberia E. M. Rivkinaa, *, D. G. Fedorov-Davydova, A. G. Zakharyukb, V. A. Shcherbakovab, and T. A. Vishnivetskayaa, c a
Institute of Physicochemical and Biological Problems of Soil Science, Russian Academy of Sciences, Pushchino, Moscow oblast, 142290 Russia b Skryabin Institute of Biochemistry and Physiology of Microorganisms, Russian Academy of Sciences, Pushchino, Moscow oblast, 142290 Russia c University of Tennessee, 1416 Circle Drive, Knoxville, TN 37996-1605 USA *e-mail: [email protected] Received March 4, 2020; revised March 21, 2020; accepted March 27, 2020
Abstract—An agreement between the content of amorphous (oxalate-extractable) iron and morphochromatic features of gley attests to the modern activity of gleyzation processes in tundra soils of the Kolyma Lowland, especially within lower parts of gentle and steep slopes. A suprapermafrost reduced gley horizon thawing out in the warmest years is considered a relic of the warmer and wetter stage of soil formation. An integrated analysis of data on the contents of mobile iron and annotated metagenomes indicates that microorganisms affiliated with the Proteobacteria phylum capable of iron reduction predominate in sediments formed under hydromorphic conditions and in modern mineral soil. In laboratory experiments, the process of microbial iron reduction was more active at 5°C than at 20°C. Therefore, it can be assumed that the majority of cultivated communities of iron-reducing bacteria have been adapted to low Arctic temperatures. Under conditions of climate warming and an increase in precipitation, permafrost temperature, and thickness of the seasonally thawed layer, iron reduction processes in the soils rich in the total iron will play an even greater role and create favorable redox conditions for the formation of methane, one of the most important greenhouse gases. Keywords: iron, metagenome, microorganisms, iron reduction DOI: 10.1134/S1064229320100166
INTRODUCTION The processes of microbiological reduction of iron, as well as sulfate reduction and denitrification, play an important role in the organic matter transformation and establishment of favorable redox conditions for the formation of methane, one of the most important greenhouse gases. Climate changes in the recent decades have caused an increase in the active layer thickness and permafrost temperature below the depth of zero annual temperature amplitude in the subarctic regions [9, 10, 14], which should lead to the activation of biological processes. Ferrous iron in soils and bottom sediments is the source of electrons for iron-oxidizing microorganisms, whereas Fe (III) can work as the final acceptor of electrons for iron reducers [13, 25, 27]. The ratio between Fe (III) and Fe (II) is indicative of the conditions of formation and cryopreservation of sediments in subarctic regions. It was found that concentrations of ferrous iron are higher than those of ferric iron in permafrost
Data Loading...
