Quantification of Motility in Bacillus subtilis at Temperatures Up to 84°C Using a Submersible Volumetric Microscope and Automated Tracking

Dubay, Megan Marie; Johnston, Nikki; Wronkiewicz, Mark; Lee, Jake; Lindensmith, Christian; Nadeau, Jay

doi:10.3389/fmicb.2022.836808

Cited by 8 publications

(2 citation statements)

References 42 publications

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“…For motile species, such as C. okenii , the ability to move within their environment, allows them to migrate to areas with better light and sulfide conditions. However, motility can also be lost as a response to environmental stressors such as nutrient scarcity (76, 77) and extreme temperatures (78, 79). Bacteria might shed their flagella to conserve energy and resources, prioritizing survival over motility.…”

Section: Discussionmentioning

confidence: 99%

Synergistic phenotypic shifts during domestication promote plankton-to-biofilm transition in purple sulfur bacteriumChromatium okenii

Di Nezio,

Ong,

Riedel

et al. 2023

Preprint

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The ability to isolate microorganisms from natural environments to pure cultures under optimized laboratory settings has markedly improved our understanding of microbial ecology. Laboratory-induced artificial growth conditions often diverge from those in natural ecosystems, forcing wild isolates into selective pressures which are distinct compared to those in nature. Consequently, fresh isolates undergo diverse eco-physiological adaptations mediated by modification of key phenotypic traits. For motile microorganisms, we still lack a biophysical understanding of the relevant traits which emerge during domestication, and possible mechanistic interrelations between them which could ultimately drive short-to-long term microbial adaptation under laboratory conditions. Here, using microfluidics, atomic force microscopy (AFM), quantitative imaging, and mathematical modelling, we study phenotypic adaptation of natural isolates of Chromatium okenii, a motile phototrophic purple sulfur bacterium (PSB) common to meromictic settings, grown under ecologically-relevant laboratory conditions over multiple generations. Our results indicate that the naturally planktonic C. okenii populations leverage synergistic shifts in cell-surface adhesive interactions, together with changes in their cell morphology, mass density, and distribution of intracellular sulfur globules, to suppress their swimming traits, ultimately switching to a sessile lifeform under laboratory conditions. A computational model of cell mechanics confirms the role of the synergistic phenotypic shifts in suppressing the planktonic lifeform. Over longer domestication periods (~10 generations), the switch from planktonic to sessile lifeform is driven by loss of flagella and enhanced adhesion. By investigating key phenotypic traits across different physiological stages of lab-grown C. okenii, we uncover a progressive loss of motility via synergistic phenotypic shifts during the early stages of domestication, which is followed by concomitant deflagellation and enhanced surface attachment that ultimately drive the transition of motile sulphur bacteria to a sessile biofilm state. Our results establish a mechanistic link between suppression of motility and surface attachment via synergistic phenotypic changes, underscoring the emergence of adaptive fitness under felicitous laboratory conditions that comes at a cost of lost ecophysiological traits tailored for natural environments.

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Section: Discussionmentioning

confidence: 99%

Synergistic phenotypic shifts during domestication promote plankton-to-biofilm transition in purple sulfur bacteriumChromatium okenii

Di Nezio,

Ong,

Riedel

et al. 2023

Preprint

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“…We recently presented tracking results for DHM recordings of cultures of Bacillus subtilis swimming at different temperatures, achieved using the LAP tracker (Dubay et al, 2022b). To obtain the tracks, the holograms were reconstructed into Z stacks, then a maximum projection was taken through the Z stack to yield a higher signal-to-noise X,Y time series.…”

Section: Introductionmentioning

confidence: 99%

Motion history images: a new method for tracking microswimmers in 3D

Riekeles,

Albalkhi,

Dubay

et al. 2024

Front. Imaging

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Quantitative tracking of rapidly moving micron-scale objects remains an elusive challenge in microscopy due to low signal-to-noise. This paper describes a novel method for tracking micron-sized motile organisms in off-axis Digital Holographic Microscope (DHM) raw holograms and/or reconstructions. We begin by processing the microscopic images with the previously reported Holographic Examination for Life-like Motility (HELM) software, which provides a variety of tracking outputs including motion history images (MHIs). MHIs are stills of videos where the frame-to-frame changes are indicated with color time-coding. This exposes tracks of objects that are difficult to identify in individual frames at a low signal-to-noise ratio. The visible tracks in the MHIs are superior to tracks identified by all tested automated tracking algorithms that start from object identification at the frame level, particularly in low signal-to-noise ratio data, but do not provide quantitative track data. In contrast to other tracking methods, like Kalman filter, where the recording is analyzed frame by frame, MHIs show the whole time span of particle movement at once and eliminate the need to identify objects in individual frames. This feature also enables post-tracking identification of low-SNR objects. We use these tracks, rather than object identification in individual frames, as a basis for quantitative tracking of Bacillus subtilis by first generating MHIs from X, Y, and t stacks (raw holograms or a projection over reconstructed planes), then using a region-tracking algorithm to identify and separate swimming pathways. Subsequently, we identify each object's Z plane of best focus at the corresponding X, Y, and t points, yielding ap full description of the swimming pathways in three spatial dimensions plus time. This approach offers an alternative to object-based tracking for processing large, low signal-to-noise datasets containing highly motile organisms.

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Advancements in bacterial chemotaxis: Utilizing the navigational intelligence of bacteria and its practical applications

Xu,

Ali,

Afzal

et al. 2024

Science of The Total Environment

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Quantification of Motility in Bacillus subtilis at Temperatures Up to 84°C Using a Submersible Volumetric Microscope and Automated Tracking

Cited by 8 publications

References 42 publications

Synergistic phenotypic shifts during domestication promote plankton-to-biofilm transition in purple sulfur bacteriumChromatium okenii

Synergistic phenotypic shifts during domestication promote plankton-to-biofilm transition in purple sulfur bacteriumChromatium okenii

Motion history images: a new method for tracking microswimmers in 3D

Advancements in bacterial chemotaxis: Utilizing the navigational intelligence of bacteria and its practical applications

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