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McGenity TJ, Laissue PP. Bacteria stretch and bend oil to feed their appetite. Science 2023; 381:728-729. [PMID: 37590354 DOI: 10.1126/science.adj4430] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/19/2023]
Abstract
Microbes reshape oil droplets to speed biodegradation.
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Affiliation(s)
- Terry J McGenity
- School of Life Sciences, University of Essex, Wivenhoe Park, CO4 3SQ, UK
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Langeslay B, Juarez G. Microdomains and stress distributions in bacterial monolayers on curved interfaces. SOFT MATTER 2023; 19:3605-3613. [PMID: 37161525 DOI: 10.1039/d2sm01498j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Monolayers of growing non-motile rod-shaped bacteria act as active nematic materials composed of hard particles rather than the flexible components of other commonly studied active nematics. The organization of these granular monolayers has been studied on flat surfaces but not on curved surfaces, which are known to change the behavior of other active nematics. We use molecular dynamics simulations to track alignment and stress in growing monolayers fixed to curved surfaces, and investigate how these vary with changing surface curvature and cell aspect ratio. We find that the length scale of alignment (measured by average microdomain size) increases with cell aspect ratio and decreases with curvature. Additionally, we find that alignment controls the distribution of extensile stresses in the monolayer by concentrating stress in negative-order regions. These results connect active nematic physics to bacterial monolayers and can be applied to model bacteria growing on droplets, such as oil-degrading marine bacteria.
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Affiliation(s)
- Blake Langeslay
- Department of Physics, University of Illinois Urbana-Champaign, Urbana, Illinois 61801, USA
| | - Gabriel Juarez
- Department of Mechanical Science and Engineering, University of Illinois Urbana-Champaign, Urbana, Illinois 61801, USA.
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A tradeoff between physical encounters and consumption determines an optimal droplet size for microbial degradation of dispersed oil. Sci Rep 2022; 12:4734. [PMID: 35304520 PMCID: PMC8933409 DOI: 10.1038/s41598-022-08581-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Accepted: 03/09/2022] [Indexed: 11/08/2022] Open
Abstract
Immiscible hydrocarbons occur in the ocean water column as droplets of varying diameters. Although microbial oil degradation is a central process in the remediation of hydrocarbon pollution in marine environments, the relationship between droplet size distribution and oil degradation rates by bacteria remains unclear, with a conflicting history of laboratory studies. Despite this knowledge gap, the use of chemical dispersants in oil spill response and mitigation is based on the rationale that increasing the surface-area-to-volume ratio of droplets will enhance net bacterial biodegradation rates. We demonstrate that this intuitive argument does not apply to most natural marine environments, where the abundance of oil droplets is much lower than in laboratory experiments and droplet-bacteria encounters are the limiting factor. We present a mechanistic encounter-consumption model to predict the characteristic time for oil degradation by marine bacteria as a function of the initial oil concentration, the distribution of droplet sizes, and the initial abundance of oil-degrading bacteria. We find that the tradeoff between the encounter time and the consumption time leads to an optimal droplet size larger than the average size generated by the application of dispersants. Reducing droplet size below this optimum can increase the persistence of oil droplets in the environment from weeks to years. The new perspective granted by this biophysical model of biodegradation that explicitly accounts for oil-microbe encounters changes our understanding of biodegradation particularly in the deep ocean, where droplets are often small and oil concentrations low, and explains degradation rate discrepancies between laboratory and field studies.
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Dewangan NK, Tran N, Wang-Reed J, Conrad JC. Bacterial aggregation assisted by anionic surfactant and calcium ions. SOFT MATTER 2021; 17:8474-8482. [PMID: 34586147 DOI: 10.1039/d1sm00479d] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
We identify factors leading to aggregation of bacteria in the presence of a surfactant using absorbance and microscopy. Two marine bacteria, Marinobacter hydrocarbonoclasticus SP17 and Halomonas titanicae Bead 10BA, formed aggregates of a broad size distribution in synthetic sea water in the presence of an anionic surfactant, dioctyl sodium sulfosuccinate (DOSS). Both DOSS at high concentrations and calcium ions were necessary for aggregate formation, but DOSS micelles were not required for aggregation. Addition of proteinase K but not DNase1 eliminated aggregate formation over two hours. Finally, swimming motility also enhanced aggregate formation.
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Affiliation(s)
- Narendra K Dewangan
- William A. Brookshire Department of Chemical and Biomolecular Engineering, University of Houston, Houston, TX, 77204-4004, USA.
| | - Nhi Tran
- William A. Brookshire Department of Chemical and Biomolecular Engineering, University of Houston, Houston, TX, 77204-4004, USA.
| | - Jing Wang-Reed
- William A. Brookshire Department of Chemical and Biomolecular Engineering, University of Houston, Houston, TX, 77204-4004, USA.
| | - Jacinta C Conrad
- William A. Brookshire Department of Chemical and Biomolecular Engineering, University of Houston, Houston, TX, 77204-4004, USA.
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Edge current and pairing order transition in chiral bacterial vortices. Proc Natl Acad Sci U S A 2021; 118:2107461118. [PMID: 34561308 DOI: 10.1073/pnas.2107461118] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/24/2021] [Indexed: 12/21/2022] Open
Abstract
Bacterial suspensions show turbulence-like spatiotemporal dynamics and vortices moving irregularly inside the suspensions. Understanding these ordered vortices is an ongoing challenge in active matter physics, and their application to the control of autonomous material transport will provide significant development in microfluidics. Despite the extensive studies, one of the key aspects of bacterial propulsion has remained elusive: The motion of bacteria is chiral, i.e., it breaks mirror symmetry. Therefore, the mechanism of control of macroscopic active turbulence by microscopic chirality is still poorly understood. Here, we report the selective stabilization of chiral rotational direction of bacterial vortices in achiral circular microwells sealed by an oil/water interface. The intrinsic chirality of bacterial swimming near the top and bottom interfaces generates chiral collective motions of bacteria at the lateral boundary of the microwell that are opposite in directions. These edge currents grow stronger as bacterial density increases, and, within different top and bottom interfaces, their competition leads to a global rotation of the bacterial suspension in a favored direction, breaking the mirror symmetry of the system. We further demonstrate that chiral edge current favors corotational configurations of interacting vortices, enhancing their ordering. The intrinsic chirality of bacteria is a key feature of the pairing order transition from active turbulence, and the geometric rule of pairing order transition may shed light on the strategy for designing chiral active matter.
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Rivas DP, Hedgecock ND, Stebe KJ, Leheny RL. Dynamic and mechanical evolution of an oil-water interface during bacterial biofilm formation. SOFT MATTER 2021; 17:8195-8210. [PMID: 34525167 DOI: 10.1039/d1sm00795e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
We present an experimental study combining particle tracking, active microrheology, and differential dynamic microscopy (DDM) to investigate the dynamics and rheology of an oil-water interface during biofilm formation by the bacteria Pseudomonas Aeruginosa PA14. The interface transitions from an active fluid dominated by the swimming motion of adsorbed bacteria at early age to an active viscoelastic system at late ages when the biofilm is established. The microrheology measurements using microscale magnetic rods indicate that the biofilm behaves as a viscoelastic solid at late age. The bacteria motility at the interface during the biofilm formation, which is characterized in the DDM measurements, evolves from diffusive motion at early age to constrained, quasi-localized motion at later age. Similarly, the mobility of passively moving colloidal spheres at the interface decreases significantly with increasing interface age and shows a dependence on sphere size after biofilm formation that is orders-of-magnitude larger than that expected in a homogeneous system in equilibrium. We attribute this anomalous size dependence to either length-scale-dependent rheology of the biofilm or widely differing effects of the bacteria activity on the motion of spheres of different sizes.
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Affiliation(s)
- David P Rivas
- Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD, 21218, USA.
| | - Nathan D Hedgecock
- Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD, 21218, USA.
| | - Kathleen J Stebe
- Department of Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Robert L Leheny
- Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD, 21218, USA.
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Baltz RH, Kao K, Link AJ, Marsili E, Reguera G, Shao Z, Vandamme EJ, Jeffries TW, Gonzalez R. Introduction to Special Issue on "Frontiers in Industrial Microbiology and Biotechnology 2020". J Ind Microbiol Biotechnol 2020; 47:621-622. [PMID: 33123834 DOI: 10.1007/s10295-020-02322-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
| | - Katy Kao
- Department of Chemical and Materials Engineering, San Jose State University, San Jose, CA, USA
| | - A James Link
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ, USA
| | - Enrico Marsili
- Department of Chemical and Materials Engineering, Nazarbayev University, Nur-Sultan, Kazakhstan
| | - Gemma Reguera
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI, USA
| | - Zengyi Shao
- Department of Chemical and Biological Engineering, Iowa State University, Ames, IA, USA
| | | | | | - Ramon Gonzalez
- Department of Chemical and Biomedical Engineering, University of South Florida, Tampa, FL, USA.
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