title: Organization of biogeochemical nitrogen pathways with switch-like adjustment in fluctuating soil redox conditions.
abstract: Nitrogen is cycled throughout ecosystems by a suite of biogeochemical processes. The high complexity of the nitrogen cycle resides in an intricate interplay between reversible biochemical pathways alternatively and specifically activated in response to diverse environmental cues. Despite aggressive research, how the fundamental nitrogen biochemical processes are assembled and maintained in fluctuating soil redox conditions remains elusive. Here, we address this question using a kinetic modelling approach coupled with dynamical systems theory and microbial genomics. We show that alternative biochemical pathways play a key role in keeping nitrogen conversion and conservation properties invariant in fluctuating environments. Our results indicate that the biochemical network holds inherent adaptive capacity to stabilize ammonium and nitrate availability, and that the bistability in the formation of ammonium is linked to the transient upregulation of theamo-haomediated nitrification pathway. The bistability is maintained by a pair of complementary subsystems acting as either source or sink type systems in response to soil redox fluctuations. It is further shown how elevated anthropogenic pressure has the potential to break down the stability of the system, altering substantially ammonium and nitrate availability in the soil, with dramatic effects on biodiversity.
authors.affiliation: School of Mathematics, Statistics and Computational Sciences , Central University of Rajasthan , Bandarsindri, Ajmer , India.
authors.forename: Sanjay
authors.initials: S
authors.lastname: Lamba
authors.affiliation: School of Mathematics, Statistics and Computational Sciences , Central University of Rajasthan , Bandarsindri, Ajmer , India.
authors.forename: Soumen
authors.initials: S
authors.lastname: Bera
authors.affiliation: School of Mathematics, Statistics and Computational Sciences , Central University of Rajasthan , Bandarsindri, Ajmer , India.
authors.forename: Mubasher
authors.initials: M
authors.lastname: Rashid
authors.affiliation: Institute of Theoretical and Experimental Biophysics , Pushchino 142290 , Russia.
authors.forename: Alexander B
authors.initials: AB
authors.lastname: Medvinsky
authors.affiliation: Department of Mathematics , Shanxi University , Taiyuan , People's Republic of China.
authors.forename: Gui-Quan
authors.identifier: 0000-0002-1831-1603
authors.initials: GQ
authors.lastname: Sun
authors.affiliation: Institute for Evolution and Biodiversity , WWU Muenster , Germany.
authors.forename: Claudia
authors.initials: C
authors.lastname: Acquisti
authors.affiliation: School of Mathematics, Statistics and Computational Sciences, Central University of Rajasthan, Bandarsindri, Ajmer, India; Ecological Complexity and Modeling Laboratory, University of California, Riverside, CA 92521-0124, USA.
authors.forename: Amit
authors.identifier: 0000-0002-2068-4011
authors.initials: A
authors.lastname: Chakraborty
authors.affiliation: Ecological Complexity and Modeling Laboratory , University of California , Riverside, CA 92521-0124 , USA.
authors.forename: Bai-Lian
authors.initials: BL
authors.lastname: Li
keywords: biochemical network; biogeochemistry; ecosystems; nitrogen cycle; self-regulation