scholarly journals Formation, collective motion, and merging of macroscopic bacterial aggregates

2022 ◽  
Vol 18 (1) ◽  
pp. e1009153
Author(s):  
George Courcoubetis ◽  
Manasi S. Gangan ◽  
Sean Lim ◽  
Xiaokan Guo ◽  
Stephan Haas ◽  
...  
Keyword(s):  
Cell Density ◽  
Collective Motion ◽  
Bacterial Species ◽  
Aggregate Size ◽  
Enterobacter Cloacae ◽  
Soft Agar ◽  
Culture Dish ◽  
Directed Movement ◽  
Collective Behaviors ◽  
Bacterial Aggregates

Chemotactic bacteria form emergent spatial patterns of variable cell density within cultures that are initially spatially uniform. These patterns are the result of chemical gradients that are created from the directed movement and metabolic activity of billions of cells. A recent study on pattern formation in wild bacterial isolates has revealed unique collective behaviors of the bacteria Enterobacter cloacae. As in other bacterial species, Enterobacter cloacae form macroscopic aggregates. Once formed, these bacterial clusters can migrate several millimeters, sometimes resulting in the merging of two or more clusters. To better understand these phenomena, we examine the formation and dynamics of thousands of bacterial clusters that form within a 22 cm square culture dish filled with soft agar over two days. At the macroscale, the aggregates display spatial order at short length scales, and the migration of cell clusters is superdiffusive, with a merging acceleration that is correlated with aggregate size. At the microscale, aggregates are composed of immotile cells surrounded by low density regions of motile cells. The collective movement of the aggregates is the result of an asymmetric flux of bacteria at the boundary. An agent-based model is developed to examine how these phenomena are the result of both chemotactic movement and a change in motility at high cell density. These results identify and characterize a new mechanism for collective bacterial motility driven by a transient, density-dependent change in motility.

scholarly journals Formation, collective motion, and merging of macroscopic bacterial aggregates

2021 ◽  
Author(s):  
James Q Boedicker ◽  
George Courcoutbetis ◽  
Manasi Gangan ◽  
Sean Lim ◽  
Xiaokan Guo ◽  
...  
Keyword(s):  
Cell Density ◽  
Collective Motion ◽  
Aggregate Size ◽  
Enterobacter Cloacae ◽  
Soft Agar ◽  
Culture Dish ◽  
Directed Movement ◽  
Collective Behaviors ◽  
Chemical Gradients ◽  
Bacterial Aggregates

Chemotactic bacteria form emergent spatial patterns of variable cell density within cultures that are initially spatially uniform. These patterns are the result of chemical gradients that are created from the directed movement and metabolic activity of billions of cells. A recent study on pattern formation in wild bacterial isolates has revealed unique collective behaviors of the bacteria Enterobacter cloacae . As in other bacteria species, Enterobacter cloacae form macroscopic aggregates. Once formed, these bacterial clusters can migrate several millimeters, sometimes resulting in the merging of two or more clusters. To better understand these phenomena, we examine the formation and dynamics of thousands of bacterial clusters that form within a 22 cm square culture dish filled with soft agar over two days. At the macroscale, the aggregates display spatial order at short length scales, and the migration of cell clusters is superdiffusive, with a merging acceleration that is correlated with aggregate size. At the microscale, aggregates are composed of immotile cells surrounded by low density regions of motile cells. The collective movement of the aggregates is the result of an asymmetric flux of bacteria at the boundary. An agent based model is developed to examine how these phenomena are the result of both chemotactic movement and a change in motility at high cell density. These results identify and characterize a new mechanism for collective bacterial motility driven by a transient, density-dependent change in motility.

scholarly journals Bacterial survival in microscopic droplets

2019 ◽  
Author(s):  
Maor Grinberg ◽  
Tomer Orevi ◽  
Shifra Steinberg ◽  
Nadav Kashtan
Keyword(s):  
Thin Films ◽  
Cell Survival ◽  
Bacterial Species ◽  
Aggregate Size ◽  
Bacterial Survival ◽  
Plant Leaves ◽  
Naked Eye ◽  
Leaf Surfaces ◽  
Bacterial Aggregates ◽  
Microbial Habitat

AbstractPlant leaves constitute a huge microbial habitat of global importance. How microorganisms survive the dry daytime on leaves and avoid desiccation is not well-understood. There is evidence that microscopic wetness in the form of thin films and micrometer-sized droplets, invisible to the naked eye, persists on leaves during daytime due to deliquescence – the absorption of water until dissolution – of hygroscopic aerosols. Here we study how such microscopic wetness affects cell survival. We show that, on surfaces drying under moderate humidity, stable microdroplets form around bacterial aggregates due to deliquescence and capillary pinning. Notably, droplet-size increases with aggregate-size and the survival of cells is higher the larger the droplet. This phenomenon was observed for 13 different bacterial species, two of which –Pseudomonas fluorescensandP. putida– were studied in depth. Microdroplet formation around aggregates are likely key to bacterial survival in a variety of unsaturated microbial habitats, including leaf surfaces.

scholarly journals Confinement discerns swarmers from planktonic bacteria

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Weijie Chen ◽  
Neha Mani ◽  
Hamid Karani ◽  
Hao Li ◽  
Sridhar Mani ◽  
...  
Keyword(s):  
Collective Motion ◽  
Bacterial Species ◽  
Agar Plate ◽  
Soft Agar ◽  
Cell Alignment ◽  
Motion Pattern ◽  
Motion Patterns ◽  
Biological Phenotype ◽  
Bacterial Swarming

Powered by flagella, many bacterial species exhibit collective motion on a solid surface commonly known as swarming. As a natural example of active matter, swarming is also an essential biological phenotype associated with virulence, chemotaxis, and host pathogenesis. Physical changes like cell elongation and hyper flagellation have been shown to accompany the swarming phenotype. Less studied, however, are the contrasts of collective motion between the swarming cells and their counterpart planktonic cells of comparable cell density. Here, we show that confining bacterial movement in circular microwells allows distinguishing bacterial swarming from collective swimming. On a soft agar plate, a novel bacterial strain Enterobacter sp. SM3 in swarming and planktonic states exhibited different motion patterns when confined to circular microwells of a specific range of sizes. When the confinement diameter was between 40 μm and 90 μm, swarming SM3 formed a single swirl motion pattern in the microwells whereas planktonic SM3 formed multiple swirls. Similar differential behavior is observed across several other species of gram-negative bacteria. We also observed 'rafting behavior' of swarming bacteria upon dilution. We hypothesize that the rafting behavior might account for the motion pattern difference. We were able to predict these experimental features via numerical simulations where swarming cells are modeled with stronger cell-cell alignment interaction. Our experimental design using PDMS microchip disk arrays enabled us to observe bacterial swarming on murine intestinal surface suggesting a new method for characterizing bacterial swarming under complex environments, such as in polymicrobial niches, and for in vivo swarming exploration.

scholarly journals Bacterial survival in microscopic surface wetness

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Maor Grinberg ◽  
Tomer Orevi ◽  
Shifra Steinberg ◽  
Nadav Kashtan
Keyword(s):  
Cell Survival ◽  
Bacterial Species ◽  
Aggregate Size ◽  
Bacterial Survival ◽  
Plant Leaves ◽  
Surface Wetness ◽  
Leaf Surfaces ◽  
Bacterial Aggregates ◽  
Microbial Habitat ◽  
Microscopic Surface

Plant leaves constitute a huge microbial habitat of global importance. How microorganisms survive the dry daytime on leaves and avoid desiccation is not well understood. There is evidence that microscopic surface wetness in the form of thin films and micrometer-sized droplets, invisible to the naked eye, persists on leaves during daytime due to deliquescence – the absorption of water until dissolution – of hygroscopic aerosols. Here, we study how such microscopic wetness affects cell survival. We show that, on surfaces drying under moderate humidity, stable microdroplets form around bacterial aggregates due to capillary pinning and deliquescence. Notably, droplet-size increases with aggregate-size, and cell survival is higher the larger the droplet. This phenomenon was observed for 13 bacterial species, two of which – Pseudomonas fluorescens and P. putida – were studied in depth. Microdroplet formation around aggregates is likely key to bacterial survival in a variety of unsaturated microbial habitats, including leaf surfaces.

scholarly journals Confinement Discerns Swarmers from Planktonic Bacteria

2020 ◽  
Author(s):  
Weijie Chen ◽  
Neha Mani ◽  
Hamid Karani ◽  
Hao Li ◽  
Sridhar Mani ◽  
...  
Keyword(s):  
Collective Motion ◽  
Bacterial Species ◽  
Agar Plate ◽  
Soft Agar ◽  
Motion Pattern ◽  
Motion Patterns ◽  
Differential Behavior ◽  
Biological Phenotype ◽  
Bacterial Swarming

AbstractPowered by flagella, many bacterial species exhibit collective motion on a solid surface commonly known as swarming. As a natural example of active matter, swarming is also an essential biological phenotype associated with virulence, chemotaxis, and host pathogenesis. Physical changes like cell elongation and hyper flagellation have been shown to accompany the swarming phenotype. However, less noticeable, are the contrasts of collective motion between the swarming cells and the planktonic cells of comparable cell density. Here, we show that confining bacterial movement in designed dimensions allows distinguishing bacterial swarming from collective swimming. We found that on a soft agar plate, a novel bacterial strain Enterobacter sp. SM3 exhibited different motion patterns in swarming and planktonic states when confined to circular microwells of a specific range of sizes. When the confinement diameter was between 40 μm and 90 μm, swarming SM3 formed a single swirl motion pattern in the microwells whereas planktonic SM3 showed multiple swirls. Similar differential behavior is observed across a range of randomly selected gram-negative bacteria. We hypothesize that the “rafting behavior” of the swarming bacteria upon dilution might account for the motion pattern difference. We verified our conjectures via numerical simulations where swarming cells are modeled with lower repulsion and more substantial alignment force. The novel technical approach enabled us to observe swarming on a non-agar tissue surface for the first time. Our work provides the basis for characterizing bacterial swarming under more sophisticated environments, such as polymicrobial swarmer detection, and in vivo swarming exploration.

scholarly journals hfqPlays Important Roles in Virulence and Stress Adaptation in Cronobacter sakazakii ATCC 29544

2015 ◽  
Vol 83 (5) ◽  
pp. 2089-2098 ◽  
Author(s):  
Seongok Kim ◽  
Hyelyeon Hwang ◽  
Kwang-Pyo Kim ◽  
Hyunjin Yoon ◽  
Dong-Hyun Kang ◽  
...  
Keyword(s):  
Pathogenic Bacteria ◽  
Bacterial Species ◽  
Soft Agar ◽  
Host Cells ◽  
Neonatal Meningitis ◽  
Animal Cells ◽  
Content Type ◽  
Flagellar Biosynthesis

Cronobacterspp. are opportunistic pathogens that cause neonatal meningitis and sepsis with high mortality in neonates. Despite the peril associated withCronobacterinfection, the mechanisms of pathogenesis are still being unraveled. Hfq, which is known as an RNA chaperone, participates in the interaction with bacterial small RNAs (sRNAs) to regulate posttranscriptionally the expression of various genes. Recent studies have demonstrated that Hfq contributes to the pathogenesis of numerous species of bacteria, and its roles are varied between bacterial species. Here, we tried to elucidate the role of Hfq inC. sakazakiivirulence. In the absence ofhfq,C. sakazakiiwas highly attenuated in disseminationin vivo, showed defects in invasion (3-fold) into animal cells and survival (103-fold) within host cells, and exhibited low resistance to hydrogen peroxide (102-fold). Remarkably, the loss ofhfqled to hypermotility on soft agar, which is contrary to what has been observed in other pathogenic bacteria. The hyperflagellated bacteria were likely to be attributable to the increased transcription of genes associated with flagellar biosynthesis in a strain lackinghfq. Together, these data strongly suggest thathfqplays important roles in the virulence ofC. sakazakiiby participating in the regulation of multiple genes.

scholarly journals An Algorithm for Global Optimization Inspired by Collective Animal Behavior

2012 ◽  
Vol 2012 ◽  
pp. 1-24 ◽  
Author(s):  
Erik Cuevas ◽  
Mauricio González ◽  
Daniel Zaldivar ◽  
Marco Pérez-Cisneros ◽  
Guillermo García
Keyword(s):  
Global Optimization ◽  
Animal Behavior ◽  
Food Source ◽  
Collective Motion ◽  
Global Optimum ◽  
Migration Routes ◽  
Collective Behaviors ◽  
Biological Laws ◽  
Harvesting Efficiency ◽  
Collective Animal Behavior

A metaheuristic algorithm for global optimization called the collective animal behavior (CAB) is introduced. Animal groups, such as schools of fish, flocks of birds, swarms of locusts, and herds of wildebeest, exhibit a variety of behaviors including swarming about a food source, milling around a central locations, or migrating over large distances in aligned groups. These collective behaviors are often advantageous to groups, allowing them to increase their harvesting efficiency, to follow better migration routes, to improve their aerodynamic, and to avoid predation. In the proposed algorithm, the searcher agents emulate a group of animals which interact with each other based on the biological laws of collective motion. The proposed method has been compared to other well-known optimization algorithms. The results show good performance of the proposed method when searching for a global optimum of several benchmark functions.

Effects of Low-energy Shock Waves on Oral Bacteria

2008 ◽  
Vol 87 (10) ◽  
pp. 928-931 ◽  
Author(s):  
K.F. Novak ◽  
M. Govindaswami ◽  
J.L. Ebersole ◽  
W. Schaden ◽  
N. House ◽  
...  
Keyword(s):  
Alveolar Bone ◽  
Antibacterial Effect ◽  
Bacterial Species ◽  
Extracorporeal Shock Wave Therapy ◽  
Oral Bacteria ◽  
Low Energy ◽  
Shock Wave Therapy ◽  
Extracorporeal Shock Wave ◽  
Bacterial Aggregates ◽  
Viability Determination

We have recently demonstrated that extracorporeal shock-wave therapy (ESWT) is effective in promoting the healing of dermal wounds and in regenerating alveolar bone lost through periodontal disease. The objective of the present study was to determine any antibacterial effect of ESWT on oral bacteria. Monoculture suspensions of 6 bacterial species were treated with 100 to 500 pulses of ESWT at energy flux densities (EFD) of 0.12 mJ/mm2, 0.22 mJ/mm2, and 0.3 mJ/mm2. Following treatment, aliquots were plated for viability determination and compared with untreated controls. ESWT showed a significant microbicidal effect for Streptococcus mutans and an unencapsulated strain of Porphyromonas gingivalis following as few as 100 pulses at 0.3 mJ/mm2 (p ≤ 0.001). In addition, a significant disruption of bacterial aggregates was observed at lower EFDs. No significant reduction in viability was observed for all other bacteria at EFDs and pulses tested (p > 0.05). These findings suggest that low-energy ESWT may be bactericidal for selected oral bacteria.

Discontinuous and continuous transitions of collective behaviors in living systems

2021 ◽  
Author(s):  
Xu Li ◽  
Tingting Xue ◽  
Yu Sun ◽  
Jingfang Fan ◽  
Hui Li ◽  
...  
Keyword(s):  
Cognitive Abilities ◽  
Collective Motion ◽  
Finite Size ◽  
Continuous Phase ◽  
Living System ◽  
Living Systems ◽  
Finite Size Scaling ◽  
Continuous Transition ◽  
Collective Behaviors ◽  
Large Groups

Abstract Living systems are full of astonishing diversity and complexity of life. Despite differences in the length scales and cognitive abilities of these systems, collective motion of large groups of individuals can emerge. It is of great importance to seek for the fundamental principles of collective motion, such as phase transitions and their natures. Via an eigen microstate approach, we have found a discontinuous transition of density and a continuous transition of velocity in the Vicsek models of collective motion, which are identified by the finite-size scaling form of order-parameter. At strong noise, living systems behave like gas. With the decrease of noise, the interactions between the particles of a living system become stronger and make them come closer. The living system experiences then a discontinuous gas-liquid like transition of density. The even stronger interactions at smaller noise make the velocity directions of particles become ordered and there is a continuous phase transition of collective motion in addition.

Effects of Qingre Huatan Huoxue prescription on biological characteristics and cell cycle proteins of esophageal cancer stem cells.

2021 ◽  
Vol 39 (15_suppl) ◽  
pp. e16052-e16052
Author(s):  
Fuchun Si
Keyword(s):  
Cell Cycle ◽  
Stem Cells ◽  
Flow Cytometry ◽  
Esophageal Cancer ◽  
Soft Agar ◽  
Biological Characteristics ◽  
Culture Dish ◽  
Serum Free ◽  
Mtt Method ◽  
Expression Rate

e16052 Background: Esophageal cancer (EC) stem cells characterized with immature differentiation, high invasion, high tumorigenesis and other biological characteristics, which are the root of the occurrence, development, recurrence, metastasis of EC. In this study, its purpose is to select and identify EC stem cells from serum-free cultured EC9706 cells, explore the effect of Chinese herbal prescription and its separated prescriptions on the biological characteristics of EC9706 stem cells, and to reveal the cytological and molecular mechanisms of Chinese herbal prescription anti-cancer. Methods: Firstly, MTT method was applied to explore the serum-free culture conditions of EC9706 stem cells in diameter of 60 mm low adhesion culture dish, at the same time, applying flow cytometry to identify the p75NTR mark ratio of each passage of cell to screenEC9706 stem cells. Next, Plotting the growth curve of EC9706 stem cells, detecting the proliferation inhibition rate EC9706 stem cells by cisplatin, soft agar clone formation, cell cycle to identify the characteristics of EC9706 stem cells by MTT method, soft agar assay, flow cytometry. Then applying MTT method and orthogonal test to screen and optimize Qingre Huatan Huoxue prescription (QHHP), using flow cytometry and western blot to test the effects of QHHP and its separated prescriptions on EC9706 stem cells appraisal indicators and Cell Cycle Proteins. Results: EC9706 cells with concentration of 8×104 cells/dish inoculateed on diameter of 60mm low adhesion culture dish, with adding 5 ml DMEM/F12 medium, a daily supplement of 20ng EGF, 10ng bFGF, per 10 to 14 days to passage one generation. After 5 generations of cell passage, the expression rate of p75NTR was 4-5%, was selected as the experimental object.EC9706 stem cells with the biological characteristics of slower adhesive growth, stronger cisplatin resistance, higher soft agar clone formation and p75NTR expression rate than that of EC9706 cells, and The cell cycle distribution was concentrated in the G0/G1 phase. 6 Chinese herbs were screened out ( Coptis coptidis, Rhizoma officinalis, Cucurbita pedicle, Toona bark, Cantharidopsis cantharidis, Augustia japonica) and compose QHHP. QHHP and its separated prescriptions could change the morphology, colony formation ability and cycle distribution of EC9706 stem cells in serum-free culture condition, which were related to the BMI1/CyclinB1 signaling pathway. Conclusions: Serum-free cell culture is a method to enrich stem cell-like cells in EC9706 cells. Qingre Huatan Huoxue prescription and its separated prescriptions inhibited the proliferation of EC9706 stem cells and change esophageal cancer stem cells characters. The mechanism of QHHP and its separated prescriptions on stem cells in EC9706 cells was related to BMI1 /CyclinB1 signaling pathway.

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