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{| class="model-ib" style="float:right; margin-left:1em; margin-bottom:1em;" ! Microbial growth rate |- | '''Approach:''' dilution incubation |- | '''Context:''' incubation, lab |- | '''Spatial scale:''' point sample |- | '''Temporal scale:''' hours to days |- | '''Uni..."

2026-05-11T19:01:20Z

Created page with "{{BreadcrumbsSecondaryProduction}} * Page authors: PRIMO * Responsible curator: Hagen Buck-Wiese ---- __TOC__ <div class="model-box"> {| class="model-ib" style="float:right; margin-left:1em; margin-bottom:1em;" ! Microbial growth rate |- | '''Approach:''' dilution incubation |- | '''Context:''' incubation, lab |- | '''Spatial scale:''' point sample |- | '''Temporal scale:''' hours to days |- | '''Uni..."

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* [[Page authors|Page authors]]: [[PRIMO]]
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__TOC__
<div class="model-box">
{| class="model-ib" style="float:right; margin-left:1em; margin-bottom:1em;"
! Microbial growth rate
|-
| '''Approach:''' dilution incubation
|-
| '''Context:''' incubation, lab
|-
| '''Spatial scale:''' point sample
|-
| '''Temporal scale:''' hours to days
|-
| '''Units:''' cells L<sup>-1</sup> h<sup>-1</sup>
|-
| '''Community captured:''' bulk, single cell
|-
| '''Co-measurements:''' cell abundance
|}
</div>
<div style="clear:both"></div>

== Method Overview ==

The dilution method isolates microbial growth rates from grazing loss by diluting a seawater sample with particle-free (0.2 µm filtered) seawater across a range of dilution factors. Dilution reduces predator-prey encounter rates proportionally, while the intrinsic growth rate of the target cells is assumed to remain constant. By measuring net growth rates across this dilution series via flow cytometry (FCM) or epifluorescence microscopy, growth rate (µ) and grazing rate (g) can be separated as the y-intercept and slope of the net growth rate vs. dilution factor regression<ref name="Landry1993">Landry, M. R., Monger, B. C., & Selph, K. E. (1993). Time-dependency of microzooplankton grazing and phytoplankton growth in the subarctic Pacific. ''Progress in Oceanography'', 32(1–4), 205–222. https://doi.org/10.1016/0079-6611(93)90014-5</ref>.

The assay can resolve bulk community rates or, when target populations are distinguishable by their optical signatures, population-specific rates.

=== Scale of measurement ===

As a bottle-based incubation, this method yields a single point measurement in space. Incubations typically run over hours to days, providing a time-averaged growth rate for the duration of the experiment.

=== Data generated ===

The primary outputs are the intrinsic growth rate µ (d<sup>-1</sup>) and the grazing rate g (d<sup>-1</sup>). Cell abundance at each dilution level is tracked by flow cytometry or microscopy over the incubation period. Carbon-based rates require cell-specific carbon content estimates.

=== Units & currency ===

Units are cells L<sup>-1</sup> h<sup>-1</sup>.

=== Sample size ===

Typical samples are < 1 L in volume per dilution treatment.

=== Repositories & databases ===

== Limitations ==

The method assumes that grazing rates scale linearly with dilution, and that the physiological state of grazers and prey does not change across dilution levels during the incubation. Bottle confinement can alter trophic interactions and the physical-chemical environment relative to in situ conditions. Nutrient addition to unamended dilution series bottles is sometimes required to prevent nutrient limitation from confounding the growth rate estimate.

== Example Applications & Protocols ==

=== Classic examples ===
* Landry et al. (1993) ''Time-dependency of microzooplankton grazing and phytoplankton growth in the subarctic Pacific'' <ref name="Landry1993" />

=== Recent applications ===
* Heneghan et al. (2024) ''The global distribution and climate resilience of marine heterotrophic prokaryotes'' <ref name="Heneghan2024">Heneghan, R. F., Holloway-Brown, J., Gasol, J. M., Herndl, G. J., Morán, X. A. G., & Galbraith, E. D. (2024). The global distribution and climate resilience of marine heterotrophic prokaryotes. ''Nature Communications'', 15, 6943. https://doi.org/10.1038/s41467-024-50635-z</ref>

=== Common calculations/conversions ===
* Carbon content per cell is required to convert cell-based rates to carbon units; typical values are 10–20 fg C cell<sup>-1</sup> for heterotrophic bacteria.

== References ==

[[Category:Main Pages|Model types]]

Growth rate from biomass observation - Revision history