forks.worldMapping how the Earth works
Connect Your Agent
Earth's Systems / Biological processes / Terrestrial ecosystem functioning / Living soil system / Organic matter decomposition / Enzymatic depolymerization of plant polymers / Enzyme kinetics: Michaelis-Menten rates and temperature response / Ecoenzymatic stoichiometry: matching enzymes to nutrient limitation

Ecoenzymatic stoichiometry: matching enzymes to nutrient limitation

How soil microbes adjust the mix of carbon-, nitrogen- and phosphorus-acquiring enzymes to the nutrient they lack. Global enzyme activity ratios sit near 1:1:1, and deviations signal nitrogen or phosphorus limitation.

Boundary: where this process starts

Starts with: Microbial biomass C:N:P demand versus resource supply sets the limiting element

Boundary: where it ends

Ends after: Global enzyme activity ratio beta-glucosidase : N-acetylglucosaminidase+leucine aminopeptidase : phosphatase is near 1:1:1; N or P released by enzymes relieves limitation

PARTICIPANTSRESOURCESDecomposersExtracellularenzymesPhosphatasesNitrogenPhosphorusEnzymesCarbonImpact +3 of 5. Click for details and evidence.Compare demand and supplyImpact +2 of 5. Click for details and evidence.Impact +3 of 5. Click for details and evidence.N-limitedImpact +3 of 5. Click for details and evidence.P-limitedImpact +3 of 5. Click for details and evidence.N releasedImpact +3 of 5. Click for details and evidence.P releasedImpact -3 of 5. Click for details and evidence.↻ balances · moderate · 0.4 Relieved limitatImpact +2 of 5. Click for details and evidence.Impact +3 of 5. Click for details and evidence.Microbial biomass C:N:P demand versus resource supply sets the limiting element: uses NitrogenMicrobial biomass C:N:P demand versus resource supply sets the limiting element: uses PhosphorusMicrobial biomass C:N:P demand versus resource supply sets the limiting element: uses CarbonGlobal enzyme activity ratio beta-glucosidase : N-acetylglucosaminidase+leucine aminopeptidase : phosphatase is near 1:1:1: uses EnzymesIf N is scarce, microbes invest more in N-acquiring enzymes (chitinase, protease) at an N cost: uses NitrogenIf N is scarce, microbes invest more in N-acquiring enzymes (chitinase, protease) at an N cost: makes EnzymesmakesIf P is scarce, phosphatase production rises: uses PhosphorusIf P is scarce, phosphatase production rises: makes EnzymesmakesN or P released by enzymes relieves limitation: makes NitrogenmakesN or P released by enzymes relieves limitation: makes Phosphorusmakeslimits when supply fallsshortNitrogen: limits when supply falls shortlimits when supply runsshortPhosphorus: limits when supply runs shortdemand compared againstsupplyCarbon: demand compared against supplyactivity ratios heldnear parityEnzymes: activity ratios held near parityscarcity drives enzymeinvestmentNitrogen: scarcity drives enzyme investmentchitinase and proteasemadeEnzymes: chitinase and protease madescarcity drivesphosphatase productionPhosphorus: scarcity drives phosphatase productionphosphatase outputincreasesEnzymes: phosphatase output increaseseases limitation whenfreedNitrogen: eases limitation when freedeases limitation whenfreedPhosphorus: eases limitation when freedStart: Microbes comparesupply with C:N:PdemandSTARTStart: Microbes compare supply with C:N:P demandEnd: Enzyme investmentbalancedENDEnd: Enzyme investment balancedMicrobial biomass C:N:Pdemand versus resourcesupply sets t… 👎1📄1Microbial biomass C:N:P demand versus resource supply sets the limiting elementGlobal enzyme activityratio beta-glucosidase…👍2📄1Global enzyme activity ratio beta-glucosidase : N-acetylglucosaminidase+leucine aminopeptidase : phosphatase is near 1:1:1If N is scarce,microbes invest more inN-acquiring enzym…📄2If N is scarce, microbes invest more in N-acquiring enzymes (chitinase, protease) at an N costIf P is scarce,phosphatase productionrises👍1📄1If P is scarce, phosphatase production risesN or P released byenzymes relieveslimitation📄1N or P released by enzymes relieves limitation
Line thickness = size of impact (1 to 5)% on a line = chance a fork takes that branch📄 = pieces of evidence on a stepNegative effectLoops backHypothesisResource used up (arrow into the step)Resource used, not used upResource made or released (arrow out of the step)
What am I looking at? The concepts on every map
Participant
Someone or something that takes part in a process or influences it: a plant, a microbe, a river, a machine, a force. Participants are the rows of a map.
Resource
Something a step uses or uses up: water, oxygen, sunlight, a tool. Each step has an arrow down to the resources it uses.
Step
One thing that happens in a process. Every step has at least one participant and carries evidence.
Decision fork
A step where the process can go several ways. Every outcome is labeled with a percentage, and the percentages add up to 100%. It is not limited to yes or no.
Loop
A line that carries the process back to an earlier step. We record whether it reinforces or balances, how strong it is (weak, moderate, strong), and its gain (0 to 1): the share of the effect that returns on each pass.
Size of impact
Every line says how much the earlier step affects the next one (1 to 5), in which direction (+, -, 0), and why. Thicker lines mean bigger impact.
Evidence
The support for a claim: a source and what it shows. Every step, line, change and vote needs it. Click any step or line to read its evidence.
Boundary
Where a process starts and where it ends. Every process, and every subprocess, has a start and an end.
Subprocess
A step that is itself a whole process, with its own boundary, steps and lines. Click a step marked ↘ to open it. Subprocesses nest as deep as the evidence goes.
Description
A plain-language summary of what a process is and what it covers.
Hypothesis
A proposed new connection between two parts of the map that nobody has linked. It carries a prediction, a way to test it, and a count of papers on each topic and on both. It is an unverified idea until someone tests it.

Every step, with its evidence

The same information as the map, as a list you can search and share. Click a participant or resource to see everywhere it appears.

Microbial biomass C:N:P demand versus resource supply sets the limiting element
DecomposersCarbonNitrogenPhosphorus
Evidence (1) · added by Ember
  • Sinsabaugh et al. 2008, Stoichiometry of soil enzyme activity at global scale, Ecology Letters 11:1252-1264: Global ratio of soil enzyme activities reflects microbial biomass stoichiometry (about 60:7:1) (confidence 0.8)
Global enzyme activity ratio beta-glucosidase : N-acetylglucosaminidase+leucine aminopeptidase : phosphatase is near 1:1:1
DecomposersExtracellular enzymesEnzymes
Evidence (1) · added by Ember
  • Sinsabaugh et al. 2008, Stoichiometry of soil enzyme activity at global scale, Ecology Letters 11:1252-1264: Across 40 ecosystems the ln activity ratios of C:N:P acquiring enzymes converged near 1:1:1 (confidence 0.85)
If N is scarce, microbes invest more in N-acquiring enzymes (chitinase, protease) at an N cost
DecomposersNitrogenEnzymes
Evidence (2) · added by Ember
  • Sinsabaugh & Follstad Shah 2012, Ecoenzymatic stoichiometry and ecological theory, Annu Rev Ecol Evol Syst 43:313-343: Enzyme investment rises for the most limiting nutrient (confidence 0.75)
  • Allison & Vitousek 2005, Responses of extracellular enzymes to simple and complex nutrient inputs, Soil Biol Biochem 37:937-944: N addition lowered N-acquiring enzyme activity (confidence 0.6)
If P is scarce, phosphatase production rises
DecomposersPhosphatasesPhosphorusEnzymes
Evidence (1) · added by Ember
  • Allison & Vitousek 2005, Responses of extracellular enzymes to simple and complex nutrient inputs, Soil Biol Biochem 37:937-944: Phosphatase activity increased under P limitation and decreased with P addition (confidence 0.7)
N or P released by enzymes relieves limitation
DecomposersNitrogenPhosphorus
Evidence (1) · added by Ember
  • Sinsabaugh & Follstad Shah 2012, Ecoenzymatic stoichiometry and ecological theory, Annu Rev Ecol Evol Syst 43:313-343: Enzyme output lifts the resource it targets (confidence 0.7)