PLoS ONE (Jan 2018)

Nitrogen supply rate regulates microbial resource allocation for synthesis of nitrogen-acquiring enzymes.

  • Kazuki Fujita,
  • Takashi Kunito,
  • Junko Matsushita,
  • Kaori Nakamura,
  • Hitoshi Moro,
  • Seishi Yoshida,
  • Hideshige Toda,
  • Shigeto Otsuka,
  • Kazunari Nagaoka

DOI
https://doi.org/10.1371/journal.pone.0202086
Journal volume & issue
Vol. 13, no. 8
p. e0202086

Abstract

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Although microorganisms will preferentially allocate resources to synthesis of nitrogen (N)-acquiring enzymes when soil N availability is low according to the resource allocation model for extracellular enzyme synthesis, a robust link between microbial N-acquiring enzyme activity and soil N concentration has not been reported. To verify this link, we measured several indices of soil N availability and enzyme activity of four N-acquiring enzymes [N-acetyl-β-glucosaminidase (NAG), protease (PR), urease (UR), and L-asparaginase (LA)] and a carbon (C)-acquiring enzyme [β-D-glucosidase (BG)] in arable and forest soils. Although the ratios of NAG/BG and PR/BG were not significantly related with indices of soil N availability, ratios of LA/BG and UR/BG were strongly and negatively related with potentially mineralizable N estimated by aerobic incubation but not with pools of labile inorganic N and organic N. These results suggest that microorganisms might allocate their resources to LA and UR synthesis in response to N supply rate rather than the size of the easily available N pools. It was also suggested that the underlying mechanism for synthesis was different between these N-acquiring enzymes in soil microorganisms: microbial LA and UR were primarily synthesized to acquire N, whereas NAG and PR syntheses were regulated not only by N availability but also by other factors.