Cell behaviors underlying Myxococcus xanthus aggregate dispersal

ABSTRACT The soil bacterium Myxococcus xanthus is a model organism with a set of diverse behaviors. These behaviors include the starvation-induced multicellular development program, in which cells move collectively to assemble multicellular aggregates. After initial aggregates have formed, some will...

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Main Authors: Patrick Murphy, Jessica Comstock, Trosporsha Khan, Jiangguo Zhang, Roy Welch, Oleg A. Igoshin
Format: Article
Language:English
Published: American Society for Microbiology 2023-10-01
Series:mSystems
Subjects:
Online Access:https://journals.asm.org/doi/10.1128/msystems.00425-23
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author Patrick Murphy
Jessica Comstock
Trosporsha Khan
Jiangguo Zhang
Roy Welch
Oleg A. Igoshin
author_facet Patrick Murphy
Jessica Comstock
Trosporsha Khan
Jiangguo Zhang
Roy Welch
Oleg A. Igoshin
author_sort Patrick Murphy
collection DOAJ
description ABSTRACT The soil bacterium Myxococcus xanthus is a model organism with a set of diverse behaviors. These behaviors include the starvation-induced multicellular development program, in which cells move collectively to assemble multicellular aggregates. After initial aggregates have formed, some will disperse, with smaller aggregates having a higher chance of dispersal. Initial aggregation is driven by two changes in cell behavior: cells slow down inside of aggregates and bias their motion by reversing direction less frequently when moving toward aggregates. However, the cell behaviors that drive dispersal are unknown. Here, we use fluorescent microscopy to quantify changes in cell behavior after initial aggregates have formed. We observe that after initial aggregate formation, cells adjust the bias in reversal timings by initiating reversals more rapidly when approaching unstable aggregates. Using agent-based modeling, we then show dispersal is predominantly generated by this change in bias, which is strong enough to overcome slowdown inside aggregates. Notably, the change in reversal bias is correlated with the nearest aggregate size, connecting cellular activity to previously observed correlations between aggregate size and fate. To determine if this connection is consistent across strains, we analyze a second M. xanthus strain with reduced levels of dispersal. We find that far fewer cells near smaller aggregates modified their bias. This implies that aggregate dispersal is under genetic control, providing a foundation for further investigations into the role it plays in the life cycle of M. xanthus. Importance Understanding the processes behind bacterial biofilm formation, maintenance, and dispersal is essential for addressing their effects on health and ecology. Within these multicellular communities, various cues can trigger differentiation into distinct cell types, allowing cells to adapt to their specific local environment. The soil bacterium Myxococcus xanthus forms biofilms in response to starvation, marked by cells aggregating into mounds. Some aggregates persist as spore-filled fruiting bodies, while others disperse after initial formation for unknown reasons. Here, we use a combination of cell tracking analysis and computational simulations to identify behaviors at the cellular level that contribute to aggregate dispersal. Our results suggest that cells in aggregates actively determine whether to disperse or persist and undergo a transition to sporulation based on a self-produced cue related to the aggregate size. Identifying these cues is an important step in understanding and potentially manipulating bacterial cell-fate decisions.
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spelling doaj.art-3c8a942027dd42b89719dca7deec02772023-11-17T03:22:37ZengAmerican Society for MicrobiologymSystems2379-50772023-10-018510.1128/msystems.00425-23Cell behaviors underlying Myxococcus xanthus aggregate dispersalPatrick Murphy0Jessica Comstock1Trosporsha Khan2Jiangguo Zhang3Roy Welch4Oleg A. Igoshin5Department of Bioengineering, Rice University , Houston, Texas, USADepartment of Biology, Syracuse University , Syracuse, New York, USADepartment of Biology, Syracuse University , Syracuse, New York, USADepartment of Bioengineering, Rice University , Houston, Texas, USADepartment of Biology, Syracuse University , Syracuse, New York, USADepartment of Bioengineering, Rice University , Houston, Texas, USAABSTRACT The soil bacterium Myxococcus xanthus is a model organism with a set of diverse behaviors. These behaviors include the starvation-induced multicellular development program, in which cells move collectively to assemble multicellular aggregates. After initial aggregates have formed, some will disperse, with smaller aggregates having a higher chance of dispersal. Initial aggregation is driven by two changes in cell behavior: cells slow down inside of aggregates and bias their motion by reversing direction less frequently when moving toward aggregates. However, the cell behaviors that drive dispersal are unknown. Here, we use fluorescent microscopy to quantify changes in cell behavior after initial aggregates have formed. We observe that after initial aggregate formation, cells adjust the bias in reversal timings by initiating reversals more rapidly when approaching unstable aggregates. Using agent-based modeling, we then show dispersal is predominantly generated by this change in bias, which is strong enough to overcome slowdown inside aggregates. Notably, the change in reversal bias is correlated with the nearest aggregate size, connecting cellular activity to previously observed correlations between aggregate size and fate. To determine if this connection is consistent across strains, we analyze a second M. xanthus strain with reduced levels of dispersal. We find that far fewer cells near smaller aggregates modified their bias. This implies that aggregate dispersal is under genetic control, providing a foundation for further investigations into the role it plays in the life cycle of M. xanthus. Importance Understanding the processes behind bacterial biofilm formation, maintenance, and dispersal is essential for addressing their effects on health and ecology. Within these multicellular communities, various cues can trigger differentiation into distinct cell types, allowing cells to adapt to their specific local environment. The soil bacterium Myxococcus xanthus forms biofilms in response to starvation, marked by cells aggregating into mounds. Some aggregates persist as spore-filled fruiting bodies, while others disperse after initial formation for unknown reasons. Here, we use a combination of cell tracking analysis and computational simulations to identify behaviors at the cellular level that contribute to aggregate dispersal. Our results suggest that cells in aggregates actively determine whether to disperse or persist and undergo a transition to sporulation based on a self-produced cue related to the aggregate size. Identifying these cues is an important step in understanding and potentially manipulating bacterial cell-fate decisions.https://journals.asm.org/doi/10.1128/msystems.00425-23bacterial developmentbiofilmscollective behaviormyxobacteria
spellingShingle Patrick Murphy
Jessica Comstock
Trosporsha Khan
Jiangguo Zhang
Roy Welch
Oleg A. Igoshin
Cell behaviors underlying Myxococcus xanthus aggregate dispersal
mSystems
bacterial development
biofilms
collective behavior
myxobacteria
title Cell behaviors underlying Myxococcus xanthus aggregate dispersal
title_full Cell behaviors underlying Myxococcus xanthus aggregate dispersal
title_fullStr Cell behaviors underlying Myxococcus xanthus aggregate dispersal
title_full_unstemmed Cell behaviors underlying Myxococcus xanthus aggregate dispersal
title_short Cell behaviors underlying Myxococcus xanthus aggregate dispersal
title_sort cell behaviors underlying myxococcus xanthus aggregate dispersal
topic bacterial development
biofilms
collective behavior
myxobacteria
url https://journals.asm.org/doi/10.1128/msystems.00425-23
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AT jiangguozhang cellbehaviorsunderlyingmyxococcusxanthusaggregatedispersal
AT roywelch cellbehaviorsunderlyingmyxococcusxanthusaggregatedispersal
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