scholarly journals Modeling of theBacillus subtilisBacterial Biofilm Growing on an Agar Substrate

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Xiaoling Wang ◽  
Guoqing Wang ◽  
Mudong Hao
Keyword(s):  
Bacterial Species ◽  
Mass Conservation ◽  
Active Biomass ◽  
Biofilm Growth ◽  
Kinetic Reaction ◽  
Biofilm Thickness ◽  
Evolution Characteristics ◽  
Agar Substrate ◽  
Conservation Principles ◽  
Growth Evolution

Bacterial biofilms are organized communities composed of millions of microorganisms that accumulate on almost any kinds of surfaces. In this paper, a biofilm growth model on an agar substrate is developed based on mass conservation principles, Fick’s first law, and Monod’s kinetic reaction, by considering nutrient diffusion between biofilm and agar substrate. Our results show biofilm growth evolution characteristics such as biofilm thickness, active biomass, and nutrient concentration in the agar substrate. We quantitatively obtain biofilm growth dependence on different parameters. We provide an alternative mathematical method to describe other kinds of biofilm growth such as multiple bacterial species biofilm and also biofilm growth on various complex substrates.

scholarly journals Evaluation of Antibacterial Effects of Fissure Sealants Containing Chitosan Nanoparticles

2021 ◽  
Vol 2021 ◽  
pp. 1-7
Author(s):  
Sedighe Sadat Hashemi kamangar ◽  
Houtan Zareian ◽  
Abbas Bahador ◽  
Maryam Pourhajibagher ◽  
Zahra Bashareh ◽  
...  
Keyword(s):  
Antimicrobial Activity ◽  
Antibacterial Effect ◽  
Bacterial Species ◽  
Chitosan Nanoparticles ◽  
Control Group ◽  
Fissure Sealants ◽  
Biofilm Inhibition ◽  
Biofilm Growth ◽  
Fissure Sealant ◽  
Significant Difference

Objectives. The present study evaluated the antimicrobial effects of fissure sealants containing chitosan nanoparticles. Materials and Methods. Antibacterial effect of Master Dent fissure sealant alone and after incorporating chitosan nanoparticles was evaluated on Streptococcus mutans, sanguis, and Lactobacillus acidophilus. Biofilm growth was evaluated by determining colony counts. Antimicrobial effect was determined on days 3, 15, and 30 by counting microbial colonies using eluted components test. One-way ANOVA, Tukey HSD tests, t test, and two-way ANOVA were used for statistical analyses (α = 0.05). Results. Biofilm inhibition test showed that fissure sealant containing 1 wt.% chitosan decreased colony counts significantly ( P < 0.05 ). Eluted components test with S. mutans and sanguis showed significant decrease in colony counts during the first 15 days in chitosan containing group; however, from day 30, antimicrobial activity decreased noticeably, with no significant difference from control group ( P > 0.05 ). Antimicrobial activity against L. acidophilus was maintained in chitosan group up to 30 days, and decrease in colony counts was significant ( P < 0.05 ). Conclusion. According to the results of this study, incorporation of 1 wt.% chitosan into fissure sealant induced an antimicrobial activity. Antibacterial effect on L. acidophilus persisted for longer time (30 days) compared to the two other bacterial species (15 days).

Two-dimensional cellular automaton model for mixed-culture biofilm

2004 ◽  
Vol 49 (11-12) ◽  
pp. 193-198 ◽  
Author(s):  
G.E. Pizarro ◽  
C. Garcia ◽  
R. Moreno ◽  
M. E. Sepulveda
Keyword(s):  
Steady State ◽  
Structural Heterogeneity ◽  
Constant Thickness ◽  
Two Dimensional ◽  
Active Biomass ◽  
Biofilm Thickness ◽  
Biofilm Model ◽  
Systems Models ◽  
Microbial Mass

Structural and microbial heterogeneity occurs in almost any type of biofilm system. General approaches for the design of biofilm systems consider biofilms as homogeneous and of constant thickness. In order to improve the design of biofilms systems, models need to incorporate structural heterogeneity and the effect of inert microbial mass. We have improved a 2D biofilm model based on cellular automata (CA) and used it to simulate multidimensional biofilms with active and inert biomass including a self-organizing development. Results indicate that the presence of inert biomass within biofilm structures does not change considerably the substrate flux into the biofilm because the active biomass is located at the surface of the biofilm. Long-term simulations revealed that although the biofilm system is highly heterogeneous and the microstructure is continuously changing, the biofilm reaches a dynamic steady-state with prediction of biofilm thickness and substrate flux stabilizing on a delimited range.

Predicting bed dynamics in three-phase, fluidized-bed biofilm reactors

1994 ◽  
Vol 29 (10-11) ◽  
pp. 231-241 ◽  
Author(s):  
H. T. Chang ◽  
B. E. Rittmann
Keyword(s):  
Fluidized Bed ◽  
Flow Rate ◽  
Liquid Flow ◽  
Gas Flow ◽  
Liquid Flow Rate ◽  
Gas Flow Rate ◽  
Biofilm Growth ◽  
Biofilm Thickness ◽  
Three Phase ◽  
Proper Design

This paper presents a unified model that inter-relates gas flow rate, liquid flow rate, and hold-ups of each of the liquid, gas, and solid phases in three-phase, fluidized-bed biofilm (TPFBB) process. It describes how carrier properties, biofilm properties, and gas and liquid flow velocities control the system dynamics, which ultimately will affect the density, thickness, and distribution of the biofilm. The paper describes the development of the mathematical model to correlate the effects of gas flow rate, liquid flow rate, solid concentration, and biofilm thickness and density. This knowledge is critically needed in light of the use of TPFBB processes in treating industrial wastewater, which often has high substrate concentration. For example, the proper design of the TPFBB process requires mathematical description of the cause-effect relationship between biofilm growth and fluidization.

scholarly journals The Arginine Deiminase Pathway Impacts Antibiotic Tolerance during Biofilm-Mediated Streptococcus pyogenes Infections

mBio ◽  
2020 ◽  
Vol 11 (4) ◽  
Author(s):  
Jeffrey A. Freiberg ◽  
Yoann Le Breton ◽  
Janette M. Harro ◽  
Devon L. Allison ◽  
Kevin S. McIver ◽  
...  
Keyword(s):  
Treatment Failure ◽  
Antibiotic Treatment ◽  
Streptococcus Pyogenes ◽  
Bacterial Infections ◽  
Bacterial Species ◽  
Arginine Deiminase ◽  
Antibiotic Tolerance ◽  
Human Pathogen ◽  
Biofilm Growth ◽  
Content Type

ABSTRACT Bacterial biofilms are responsible for a variety of serious human infections and are notoriously difficult to treat due to their recalcitrance to antibiotics. Further work is necessary to elicit a full understanding of the mechanism of this antibiotic tolerance. The arginine deiminase (ADI) pathway is responsible for bacterial pH maintenance and is highly expressed during biofilm growth in multiple bacterial species. Using the group A Streptococcus (GAS) as a model human pathogen, the ADI pathway was demonstrated to contribute to biofilm growth. The inability of antibiotics to reduce GAS populations when in a biofilm was demonstrated by in vitro studies and a novel animal model of nasopharyngeal infection. However, disruption of the ADI pathway returned GAS biofilms to planktonic levels of antibiotic sensitivity, suggesting the ADI pathway is influential in biofilm-related antibiotic treatment failure and provides a new strategic target for the treatment of biofilm infections in GAS and potentially numerous other bacterial species. IMPORTANCE Biofilm-mediated bacterial infections are a major threat to human health because of their recalcitrance to antibiotic treatment. Through the study of Streptococcus pyogenes, a significant human pathogen that is known to form antibiotic-tolerant biofilms, we demonstrated the role that a bacterial pathway known for responding to acid stress plays in biofilm growth and antibiotic tolerance. This not only provides some insight into antibiotic treatment failure in S. pyogenes infections but also, given the widespread nature of this pathway, provides a potentially broad target for antibiofilm therapies. This discovery has the potential to impact the treatment of many different types of recalcitrant biofilm infections.

scholarly journals Architectural transitions in Vibrio cholerae biofilms at single-cell resolution

2016 ◽  
Vol 113 (14) ◽  
pp. E2066-E2072 ◽  
Author(s):  
Knut Drescher ◽  
Jörn Dunkel ◽  
Carey D. Nadell ◽  
Sven van Teeffelen ◽  
Ivan Grnja ◽  
...  
Keyword(s):  
Single Cell ◽  
Vibrio Cholerae ◽  
Biofilm Formation ◽  
Bacterial Species ◽  
Bacterial Biomass ◽  
Biofilm Growth ◽  
Glass Substrates ◽  
Critical Transitions ◽  
Cell Shapes ◽  
Biofilm Development

Many bacterial species colonize surfaces and form dense 3D structures, known as biofilms, which are highly tolerant to antibiotics and constitute one of the major forms of bacterial biomass on Earth. Bacterial biofilms display remarkable changes during their development from initial attachment to maturity, yet the cellular architecture that gives rise to collective biofilm morphology during growth is largely unknown. Here, we use high-resolution optical microscopy to image all individual cells in Vibrio cholerae biofilms at different stages of development, including colonies that range in size from 2 to 4,500 cells. From these data, we extracted the precise 3D cellular arrangements, cell shapes, sizes, and global morphological features during biofilm growth on submerged glass substrates under flow. We discovered several critical transitions of the internal and external biofilm architectures that separate the major phases of V. cholerae biofilm growth. Optical imaging of biofilms with single-cell resolution provides a new window into biofilm formation that will prove invaluable to understanding the mechanics underlying biofilm development.

scholarly journals Heterogeneity in surface sensing produces a division of labor in Pseudomonas aeruginosa populations

2019 ◽  
Author(s):  
Catherine R. Armbruster ◽  
Calvin K. Lee ◽  
Jessica Parker-Gilham ◽  
Jaime de Anda ◽  
Aiguo Xia ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Division Of Labor ◽  
Bacterial Species ◽  
Biofilm Growth ◽  
Surface Attachment ◽  
Sensing Systems ◽  
Current Thinking ◽  
Surface Exploration ◽  
Surface Sensing ◽  
Second Messenger Signaling

AbstractThe second messenger signaling molecule cyclic diguanylate monophosphate (c-di-GMP) drives the transition from planktonic to biofilm growth in many bacterial species. Pseudomonas aeruginosa has two surface sensing systems that produce c-di-GMP in response to surface adherence. The current thinking in the field is that once cells attach to a surface, they uniformly respond with elevated c-di-GMP. Here, we describe how the Wsp system generates heterogeneity in surface sensing, resulting in two physiologically distinct subpopulations of cells. One subpopulation has elevated c-di-GMP and produces biofilm matrix, serving as the founders of initial microcolonies. The other subpopulation has low c-di-GMP and engages in surface motility, allowing for exploration of the surface. We also show that this heterogeneity strongly correlates to surface behavior for descendent cells. Together, our results suggest that after surface attachment, P. aeruginosa engages in a division of labor that persists across generations, accelerating early biofilm formation and surface exploration.

scholarly journals Modeling of symbiotic bacterial biofilm growth with an example of the Streptococcus-Veillonella sp. system

2020 ◽  
Author(s):  
Dianlei Feng ◽  
Insa Neuweiler ◽  
Regina Nogueira ◽  
Udo Nackenhorst
Keyword(s):  
Numerical Solutions ◽  
Bacterial Biofilm ◽  
Thickness Direction ◽  
Biomass Distribution ◽  
Biofilm Growth ◽  
Numerical Examples ◽  
Biofilm Thickness ◽  
Coupled Partial Differential Equations ◽  
Numerical Investigations ◽  
Numerical Strategy

AbstractWe present a multi-dimensional continuum mathematical model for modeling the growth of a symbiotic biofilm system. We take a dual-species namely, the Streptococcus - Veillonella sp. biofilm system as an example for numerical investigations. The presented model describes both the cooperation and competition between these species of bacteria. The coupled partial differential equations are solved by using an integrative finite element numerical strategy. Numerical examples are carried out for studying the evolution and distribution of the bio-components. The results demonstrate that the presented model is capable of describing the symbiotic behavior of the biofilm system. However, homogenized numerical solutions are observed locally. To study the homogenization behavior of the model, numerical investigations regarding on how random initial biomass distribution influences the homogenization process are carried out. We found that a smaller correlation length of the initial biomass distribution leads to faster homogenization of the solution globally, however, shows more fluctuated biomass profiles along the biofilm thickness direction. More realistic scenarios with bacteria in patches are also investigated numerically in this study.

scholarly journals A universal microfluidic approach for quantitative study of bacterial biofilms

2021 ◽  
Author(s):  
Yuzhen Zhang ◽  
Lingbin Zeng ◽  
Yumin Cai ◽  
Zhaoyuan Chen ◽  
Peng Liu ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Quantitative Study ◽  
Bacterial Species ◽  
Metabolic Cost ◽  
Oxygen Limitation ◽  
Bacterial Biofilms ◽  
Extracellular Matrix Component ◽  
Matrix Component ◽  
Fluorescent Substance ◽  
Biofilm Growth

Bacteria usually live in densely packed communities called biofilms, where interactions between the bacteria give rise to complex properties. Quantitative analysis is indispensable in understanding those properties. However, current biofilm culturing approaches impose various limitations to these types of analysis. Here, we developed a microfluidic approach for quantitative study of biofilms, which is universal and can be used to culture biofilms of various bacterial species. To demonstrate the advantages of this approach, we present two examples, both of which revealed new biological insights. In the first example, we explored the response of Escherichia coli biofilms to exogenous hydrogen peroxide; We found the biofilms gained resistance to H2O2, but their growth was slowed down due to the metabolic cost of maintaining the resistance; However, under oxygen limitation, H2O2 can anti-intuitively boost biofilm growth. In the second example, we explored resource retention by Pseudomonas aeruginosa biofilms; We observed a fluorescent substance within the biofilm and identified it as the siderophore pyoverdine; We further showed that the extracellular matrix component Psl acted as a retention barrier for pyoverdine, minimizing its loss into the environment and therefore potentially promoting sharing of pyoverdine within the biofilm.

scholarly journals Heterogeneity in surface sensing suggests a division of labor in Pseudomonas aeruginosa populations

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Catherine R Armbruster ◽  
Calvin K Lee ◽  
Jessica Parker-Gilham ◽  
Jaime de Anda ◽  
Aiguo Xia ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Division Of Labor ◽  
Bacterial Species ◽  
Biofilm Growth ◽  
Surface Attachment ◽  
Sensing Systems ◽  
Current Thinking ◽  
Surface Exploration ◽  
Surface Sensing ◽  
Second Messenger Signaling

The second messenger signaling molecule cyclic diguanylate monophosphate (c-di-GMP) drives the transition between planktonic and biofilm growth in many bacterial species. Pseudomonas aeruginosa has two surface sensing systems that produce c-di-GMP in response to surface adherence. Current thinking in the field is that once cells attach to a surface, they uniformly respond by producing c-di-GMP. Here, we describe how the Wsp system generates heterogeneity in surface sensing, resulting in two physiologically distinct subpopulations of cells. One subpopulation has elevated c-di-GMP and produces biofilm matrix, serving as the founders of initial microcolonies. The other subpopulation has low c-di-GMP and engages in surface motility, allowing for exploration of the surface. We also show that this heterogeneity strongly correlates to surface behavior for descendent cells. Together, our results suggest that after surface attachment, P. aeruginosa engages in a division of labor that persists across generations, accelerating early biofilm formation and surface exploration.

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