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

• Published in: PloS one Vol. 13; no. 8; p. e0202086
• Main Authors: Fujita, Kazuki, Kunito, Takashi, Matsushita, Junko, Nakamura, Kaori, Moro, Hitoshi, Yoshida, Seishi, Toda, Hideshige, Otsuka, Shigeto, Nagaoka, Kazunari
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 14.08.2018; Public Library of Science (PLoS)
• Subjects: Analysis; Arable land; Asparaginase; Availability; Bacteriology; beta-Glucosidase; Biochemistry; Biology; Biology and Life Sciences; Ecology and Environmental Sciences; Ecosystem biology; Ecosystems; Environmental science; Enzymatic activity; Enzyme activity; Enzyme synthesis; Enzymes; Experiments; Forest soils; Glucosaminidase; Glucosidase; Incubation; L-asparaginase; Microbiology; Microorganisms; Nitrates; Nitrogen; Nitrogen - chemistry; Nitrogen - metabolism; Phosphatase; Phosphorus; Physical Sciences; Pools; Resource allocation; Soil - chemistry; Soil Microbiology; Soil microorganisms; Soil nitrogen; Soil sciences; Synthesis; Urease; Japan
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0202086

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.