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The chemical neighborhood of cells in a diffusion-limited system

Microorganisms follow us everywhere, and they will be essential to sustaining long-term human space exploration through applications such as vitamin synthesis, biomining, and more. Establishing a sustainable presence in space therefore requires that we better understand how stress due to the altered...

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Autores principales: Gesztesi, Juliana, Broddrick, Jared T., Lannin, Timothy, Lee, Jessica A.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Frontiers Media S.A. 2023
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10151505/
https://www.ncbi.nlm.nih.gov/pubmed/37143535
http://dx.doi.org/10.3389/fmicb.2023.1155726
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author Gesztesi, Juliana
Broddrick, Jared T.
Lannin, Timothy
Lee, Jessica A.
author_facet Gesztesi, Juliana
Broddrick, Jared T.
Lannin, Timothy
Lee, Jessica A.
author_sort Gesztesi, Juliana
collection PubMed
description Microorganisms follow us everywhere, and they will be essential to sustaining long-term human space exploration through applications such as vitamin synthesis, biomining, and more. Establishing a sustainable presence in space therefore requires that we better understand how stress due to the altered physical conditions of spaceflight affects our companion organisms. In microgravity environments such as orbital space stations, microorganisms likely experience the change in gravity primarily through changes in fluid mixing processes. Without sedimentation and density-driven convection, diffusion becomes the primary process governing the movement of growth substrates and wastes for microbial cells in suspension culture. Non-motile cells might therefore develop a substrate-deficient “zone of depletion” and experience stress due to starvation and/or waste build-up. This would in turn impact the concentration-dependent uptake rate of growth substrates and could be the cause of the altered growth rates previously observed in microorganisms in spaceflight and in ground-simulated microgravity. To better understand the extent of these concentration differences and their potential influence on substrate uptake rates, we used both an analytical solution and finite difference method to visualize concentration fields around individual cells. We modeled diffusion, using Fick’s Second Law, and nutrient uptake, using Michaelis–Menten kinetics, and assessed how that distribution varies in systems with multiple cells and varied geometries. We determined the radius of the zone of depletion, within which cells had reduced the substrate concentration by 10%, to be 5.04 mm for an individual Escherichia coli cell in the conditions we simulated. However, we saw a synergistic effect with multiple cells near each other: multiple cells in close proximity decreased the surrounding concentration by almost 95% from the initial substrate concentration. Our calculations provide researchers an inside look at suspension culture behavior in the diffusion-limited environment of microgravity at the scale of individual cells.
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spelling pubmed-101515052023-05-03 The chemical neighborhood of cells in a diffusion-limited system Gesztesi, Juliana Broddrick, Jared T. Lannin, Timothy Lee, Jessica A. Front Microbiol Microbiology Microorganisms follow us everywhere, and they will be essential to sustaining long-term human space exploration through applications such as vitamin synthesis, biomining, and more. Establishing a sustainable presence in space therefore requires that we better understand how stress due to the altered physical conditions of spaceflight affects our companion organisms. In microgravity environments such as orbital space stations, microorganisms likely experience the change in gravity primarily through changes in fluid mixing processes. Without sedimentation and density-driven convection, diffusion becomes the primary process governing the movement of growth substrates and wastes for microbial cells in suspension culture. Non-motile cells might therefore develop a substrate-deficient “zone of depletion” and experience stress due to starvation and/or waste build-up. This would in turn impact the concentration-dependent uptake rate of growth substrates and could be the cause of the altered growth rates previously observed in microorganisms in spaceflight and in ground-simulated microgravity. To better understand the extent of these concentration differences and their potential influence on substrate uptake rates, we used both an analytical solution and finite difference method to visualize concentration fields around individual cells. We modeled diffusion, using Fick’s Second Law, and nutrient uptake, using Michaelis–Menten kinetics, and assessed how that distribution varies in systems with multiple cells and varied geometries. We determined the radius of the zone of depletion, within which cells had reduced the substrate concentration by 10%, to be 5.04 mm for an individual Escherichia coli cell in the conditions we simulated. However, we saw a synergistic effect with multiple cells near each other: multiple cells in close proximity decreased the surrounding concentration by almost 95% from the initial substrate concentration. Our calculations provide researchers an inside look at suspension culture behavior in the diffusion-limited environment of microgravity at the scale of individual cells. Frontiers Media S.A. 2023-04-18 /pmc/articles/PMC10151505/ /pubmed/37143535 http://dx.doi.org/10.3389/fmicb.2023.1155726 Text en Copyright © 2023 Gesztesi, Broddrick, Lannin and Lee. https://creativecommons.org/licenses/by/4.0/This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
spellingShingle Microbiology
Gesztesi, Juliana
Broddrick, Jared T.
Lannin, Timothy
Lee, Jessica A.
The chemical neighborhood of cells in a diffusion-limited system
title The chemical neighborhood of cells in a diffusion-limited system
title_full The chemical neighborhood of cells in a diffusion-limited system
title_fullStr The chemical neighborhood of cells in a diffusion-limited system
title_full_unstemmed The chemical neighborhood of cells in a diffusion-limited system
title_short The chemical neighborhood of cells in a diffusion-limited system
title_sort chemical neighborhood of cells in a diffusion-limited system
topic Microbiology
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10151505/
https://www.ncbi.nlm.nih.gov/pubmed/37143535
http://dx.doi.org/10.3389/fmicb.2023.1155726
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