The microbial world essentially shapes every facet of our lives. Whether they are in the soil where our food is grown, or in the lungs of an infected person, or on the ocean floor, microbes live in diverse communities made up of multiple species that all work together and influence each other. each other. Just like in our own neighborhoods, the geography of a microbial community’s disposition affects how those microbes live and function together.
Now, Caltech researchers have discovered that changes in local oxygen concentration have dramatic impacts on the life or death of microbial neighbors in the presence of a common microbial byproduct, nitric oxide (NO). The results suggest that large-scale global models, such as those of the nitrogen cycle, should work to account for the fact that micro-scale chemical environments affect microbial behavior.
An article describing the research appears in the journal Current biology October 27. The study was led by graduate student Steven Wilbert and performed in the lab of Dianne Newman, Gordon M. Binder/Amgen Professor of Biology and Geobiology and Managing Director of Biology and Bioengineering.
Nitric oxide is produced as an intermediate in the multi-step process of converting nitrate (NO3–) to nitrogen gas (N2). This whole process, called denitrification, is a crucial part of biological processes across the planet. Recent research has shown that different steps in this pathway can be performed by different members of various microbial communities.
To examine how a microbe’s local environment affects its ability to perform the denitrification process, Wilbert used Pseudomonas aeruginosa, a bacterium extensively studied in Newman’s lab as a model organism. Using genetic engineering techniques, Wilbert produced a strain that performed only the first half of the denitrification pathway and another strain that performed only the second half of the pathway.
Next, Wilbert studied how these two modified bacterial strains interact in different oxygen environments. The idea was that the “first half” strain produced NO as a by-product, and the team aimed to find out how the “second half” strain would manage NO under different local oxygen concentrations, and how, at in turn, this would affect the whole community.
The study showed that in the absence of oxygen, the second strain of genetically modified Pseudomonas was able to take the NO produced by the first and chemically modify or reduce this chemical as part of the normal denitrification process. . In addition, the bacteria were able to use NO as a substrate on which to grow. However, in an environment with higher concentrations of oxygen, NO became toxic, killing strains of Pseudomonas that could not reduce the molecule.
“Oxygen regulates these microbial interactions dramatically: they can live or die because of it,” says Newman. “This, in turn, affects the whole process of denitrification. Models that attempt to account for the contribution of microorganisms to the nitrogen cycle must therefore take into account the microscopic spatial environment. This is a really important variable.”
While the study revealed the specifics of how oxygen mediates cellular interactions with NO, the research also points to more general principles regarding a broad class of microbial by-products. NO is an example of a “redox-active metabolite” or RAM. This study provides a new way to study how the impacts of RAMs on microbes are affected by their local microenvironment, which can be highly variable in space and time.
“Microbial metabolism is like a race to pick up and drop electrons,” says Wilbert. “Essentially, all of life is about this transfer of energy. RAMs, with their ability to donate or receive electrons, serve as an important currency of exchange between microbial neighbors. While it may facilitate energy transfer, RAMs are sensitive to changes in local oxygen concentrations that vary in the atmosphere. Due to our results with NO, we are convinced that oxygen is the key to a clearer picture of what is happening in invisible soils, oceans and anywhere microbial interactions may occur. If we understand how oxygen is changing in the micro-scale environment, we can make better predictions about how microbial communities survive in the lungs or in human systems. agricultural.”
The article is titled “Contrasting roles of nitric oxide drive microbial community organization based on the presence of oxygen”.
Climate-warming microbes thrive in drying peatlands
Steven A. Wilbert et al, Contrasting roles of nitric oxide drive microbial community organization based on the presence of oxygen, Current biology (2022). DOI: 10.1016/j.cub.2022.10.008
Provided by California Institute of Technology
Quote: A microbe’s local environment can mean the difference between life and death (October 28, 2022) Retrieved October 29, 2022 from https://phys.org/news/2022-10-microbe-local-environment- difference-life.html
This document is subject to copyright. Except for fair use for purposes of private study or research, no part may be reproduced without written permission. The content is provided for information only.
#microbes #local #environment #difference #life #death