A Selection of Platforms to Evaluate Surface Adhesion and Biofilm Formation in Controlled Hydrodynamic Conditions

The early colonization of surfaces and subsequent biofilm development have severe impacts in environmental, industrial, and biomedical settings since they entail high costs and health risks. To develop more effective biofilm control strategies, there is a need to obtain laboratory biofilms that resemble those found in natural or man-made settings. Since microbial adhesion and biofilm formation are strongly affected by hydrodynamics, the knowledge of flow characteristics in different marine, food processing, and medical device locations is essential. Once the hydrodynamic conditions are known, platforms for cell adhesion and biofilm formation should be selected and operated, in order to obtain reproducible biofilms that mimic those found in target scenarios. This review focuses on the most widely used platforms that enable the study of initial microbial adhesion and biofilm formation under controlled hydrodynamic conditions—modified Robbins devices, flow chambers, rotating biofilm devices, microplates, and microfluidic devices—and where numerical simulations have been used to define relevant flow characteristics, namely the shear stress and shear rate.

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Persistent Listeria monocytogenes Isolates from a Poultry-Processing Facility Form More Biofilm but Do Not Have a Greater Resistance to Disinfectants than Sporadic Strains

Pathogens ◽

10.3390/pathogens8040250 ◽

2019 ◽

Vol 8 (4) ◽

pp. 250 ◽

Cited By ~ 3

Author(s):

Daniel Rodríguez-Campos ◽

Cristina Rodríguez-Melcón ◽

Carlos Alonso-Calleja ◽

Rosa Capita

Keyword(s):

Listeria Monocytogenes ◽

Food Processing ◽

Biofilm Formation ◽

Benzalkonium Chloride ◽

Bacterial Persistence ◽

Crystal Violet Assay ◽

Processing Facility ◽

Poultry Processing ◽

Sessile Cells ◽

Selection Of

Some strains of Listeria monocytogenes can persist in food-processing environments, increasing the likelihood of the contamination of foodstuffs. To identify traits that contribute to bacterial persistence, a selection of persistent and sporadic L. monocytogenes isolates from a poultry-processing facility was investigated for biofilm-forming ability (crystal violet assay). The susceptibility of sessile cells to treatments (five minutes) with sodium hypochlorite having 10% active chlorine (SHY: 10,000 ppm, 25,000 ppm, and 50,000 ppm) and benzalkonium chloride (BZK: 2500 ppm, 10,000 ppm, and 25,000 ppm) was also studied. All isolates exhibited biofilm formation on polystyrene. Persistent strains showed larger (p < 0.001) biofilm formation (OD580 = 0.301 ± 0.097) than sporadic strains (OD580 = 0.188 ± 0.082). A greater susceptibility to disinfectants was observed for biofilms of persistent strains than for those of sporadic strains. The application of SHY reduced biofilms only for persistent strains. BZK increased OD580 in persistent strains (2500 ppm) and in sporadic strains (all concentrations). These results indicate that the use of BZK at the concentrations tested could represent a public health risk. Findings in this work suggest a link between persistence and biofilm formation, but do not support a relationship between persistence and the resistance of sessile cells to disinfectants.

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The Relative Importance of Shear Forces and Surface Hydrophobicity on Biofilm Formation by Coccoid Cyanobacteria

Polymers ◽

10.3390/polym12030653 ◽

2020 ◽

Vol 12 (3) ◽

pp. 653 ◽

Cited By ~ 3

Author(s):

Sara I. Faria ◽

Rita Teixeira-Santos ◽

Maria J. Romeu ◽

João Morais ◽

Vitor Vasconcelos ◽

...

Keyword(s):

Biofilm Formation ◽

Hydrophobic Surface ◽

Surface Hydrophobicity ◽

Polymeric Coating ◽

Relative Importance ◽

Hydrodynamic Conditions ◽

Shear Forces ◽

Lower Shear ◽

Biofilm Development ◽

The Impact

Understanding the conditions affecting cyanobacterial biofilm development is crucial to develop new antibiofouling strategies and decrease the economic and environmental impact of biofilms in marine settings. In this study, we investigated the relative importance of shear forces and surface hydrophobicity on biofilm development by two coccoid cyanobacteria with different biofilm formation capacities. The strong biofilm-forming Synechocystis salina was used along with the weaker biofilm-forming Cyanobium sp. Biofilms were developed in defined hydrodynamic conditions using glass (a model hydrophilic surface) and a polymeric epoxy coating (a hydrophobic surface) as substrates. Biofilms developed in both surfaces at lower shear conditions contained a higher number of cells and presented higher values for wet weight, thickness, and chlorophyll a content. The impact of hydrodynamics on biofilm development was generally stronger than the impact of surface hydrophobicity, but a combined effect of these two parameters strongly affected biofilm formation for the weaker biofilm-producing organism. The antibiofilm performance of the polymeric coating was confirmed at the hydrodynamic conditions prevailing in ports. Shear forces were shown to have a profound impact on biofilm development in marine settings regardless of the fouling capacity of the existing flora and the hydrophobicity of the surface.

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Counteracting Bacterial Motility: A Promising Strategy to Narrow Listeria monocytogenes Biofilm in Food Processing Industry

Frontiers in Microbiology ◽

10.3389/fmicb.2021.673484 ◽

2021 ◽

Vol 12 ◽

Author(s):

Ibtissem Doghri ◽

Tamazight Cherifi ◽

Coralie Goetz ◽

François Malouin ◽

Mario Jacques ◽

...

Keyword(s):

Listeria Monocytogenes ◽

Food Processing ◽

Biofilm Formation ◽

Ethylenediaminetetraacetic Acid ◽

Early Stage ◽

Critical Role ◽

Significant Inhibition ◽

Bacterial Motility ◽

Coagulase Negative Staphylococci ◽

Biofilm Development

Listeria monocytogenes (L. monocytogenes) is often associated with processed food as it can form biofilms that represent a source of contamination at all stages of the manufacturing chain. The control and prevention of biofilms in food-processing plants are of utmost importance. This study explores the efficacy of prospect molecules for counteracting bacterial mechanisms leading to biofilm formation. The compounds included the phytomolecule tomatidine, zinc chloride (ZnCl2), ethylenediaminetetraacetic acid (EDTA), and a more complexed mixture of bacterial compounds from coagulase-negative staphylococci (CNS exoproducts). Significant inhibition of L. monocytogenes biofilm formation was evidenced using a microfluidic system and confocal microscopic analyses (p < 0.001). Active molecules were effective at an early stage of biofilm development (≥50% of inhibition) but failed to disperse mature biofilms of L. monocytogenes. According to our findings, prevention of surface attachment was associated with a disruption of bacterial motility. Indeed, agar cell motility assays demonstrated the effectiveness of these molecules. Overall, results highlighted the critical role of motility in biofilm formation and allow to consider flagellum-mediated motility as a promising molecular target in control strategies against L. monocytogenes in food processing environments.

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The ComX Quorum Sensing Peptide of Bacillus subtilis Affects Biofilm Formation Negatively and Sporulation Positively

Microorganisms ◽

10.3390/microorganisms8081131 ◽

2020 ◽

Vol 8 (8) ◽

pp. 1131 ◽

Cited By ~ 1

Author(s):

Mihael Špacapan ◽

Tjaša Danevčič ◽

Polonca Štefanic ◽

Michael Porter ◽

Nicola R. Stanley-Wall ◽

...

Keyword(s):

Bacillus Subtilis ◽

Quorum Sensing ◽

Biofilm Formation ◽

Matrix Protein ◽

Control Strategies ◽

Wild Type ◽

Fibrous Matrix ◽

Sensing System ◽

Quorum Sensing System ◽

Biofilm Development

Quorum sensing (QS) is often required for the formation of bacterial biofilms and is a popular target of biofilm control strategies. Previous studies implicate the ComQXPA quorum sensing system of Bacillus subtilis as a promoter of biofilm formation. Here, we report that ComX signaling peptide deficient mutants form thicker and more robust pellicle biofilms that contain chains of cells. We confirm that ComX positively affects the transcriptional activity of the PepsA promoter, which controls the synthesis of the major matrix polysaccharide. In contrast, ComX negatively controls the PtapA promoter, which drives the production of TasA, a fibrous matrix protein. Overall, the biomass of the mutant biofilm lacking ComX accumulates more monosaccharide and protein content than the wild type. We conclude that this QS phenotype might be due to extended investment into growth rather than spore development. Consistent with this, the ComX deficient mutant shows a delayed activation of the pre-spore specific promoter, PspoIIQ, and a delayed, more synchronous commitment to sporulation. We conclude that ComX mediated early commitment to sporulation of the wild type slows down biofilm formation and modulates the coexistence of multiple biological states during the early stages of biofilm development.

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The Impact of Shear Forces and Surface Hydrophobicity on Coccoid Cyanobacterial Biofilm Development

10.5194/biofilms9-33 ◽

2020 ◽

Author(s):

Sara I. Faria ◽

Rita Teixeira-Santos ◽

Maria J. Romeu ◽

João Morais ◽

Vítor Vasconcelos ◽

...

Keyword(s):

Biofilm Formation ◽

Hydrophobic Surface ◽

Surface Hydrophobicity ◽

Polymeric Coating ◽

Hydrodynamic Conditions ◽

Shear Forces ◽

Lower Shear ◽

Biofilm Development ◽

The Impact ◽

Cyanobacterial Biofilm

Biofouling is a natural process in marine environments with associated economic and ecological problems. Thus, understanding the conditions that affect cyanobacterial biofilm development is crucial to develop new antibiofouling strategies and decrease the impact of biofilms in the marine environment. In this study, we investigated the relative importance of shear forces and surface hydrophobicity on biofilm development by two coccoid cyanobacteria with different biofilm formation capacities. The strong biofilm-forming Synechocystis salina was used along with the weaker biofilm-forming Cyanobium sp. Biofilms were developed in defined hydrodynamic conditions using glass (a model hydrophilic surface) and a polymeric epoxy coating (a hydrophobic surface) as substrates. Biofilms developed in both surfaces at lower shear conditions contained a higher number of cells and presented higher values for wet weight, thickness, and chlorophyll a content. The impact of hydrodynamics on biofilm development was generally stronger than the impact of surface hydrophobicity, but a combined effect of these two parameters strongly affected biofilm formation for the weaker biofilm-producing organism. The antibiofilm performance of the polymeric coating was confirmed at the hydrodynamic conditions prevailing in ports. Shear forces were shown to have a profound impact on biofilm development in marine settings regardless of the fouling capacity of the existing flora and the hydrophobicity of the surface.

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Antimicrobial Pressure of Ciprofloxacin and Gentamicin on Biofilm Development by an Endoscope-Isolated Pseudomonas aeruginosa

ISRN Biotechnology ◽

10.5402/2013/178646 ◽

2013 ◽

Vol 2013 ◽

pp. 1-10 ◽

Cited By ~ 4

Author(s):

Idalina Machado ◽

Joana Graça ◽

Hélder Lopes ◽

Susana Lopes ◽

Maria O. Pereira

Keyword(s):

Pseudomonas Aeruginosa ◽

Biofilm Formation ◽

Benzalkonium Chloride ◽

Reference Strain ◽

Bacterial Attachment ◽

Cross Resistance ◽

Persister Cells ◽

Development Of Resistance ◽

Biofilm Development ◽

Selection Of

This work aims at characterizing endoscope biofilm-isolated (PAI) and reference strain P. aeruginosa (PA) adhesion, biofilm formation and sensitivity to antibiotics. The recovery ability of the biofilm-growing bacteria subjected to intermittent antibiotic pressure (ciprofloxacin (CIP) and gentamicin (GM)), as well as the development of resistance towards antibiotics and benzalkonium chloride (BC), were also determined. The capacity of both strains to develop biofilms was greatly impaired in the presence of CIP and GM. Sanitization was not complete allowing biofilm recovery after the intermittent cycles of antibiotic pressure. The environmental pressure exerted by CIP and GM did not develop P. aeruginosa resistance to antibiotics nor cross-resistance towards BC. However, data highlighted that none of the antimicrobials led to complete biofilm eradication, allowing the recovery of the remaining adhered population possibly due to the selection of persister cells. This feature may lead to biofilm recalcitrance, reinforcement of bacterial attachment, and recolonization of other sites.

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Effect of gravitational deposition on biofilm formation and development

Biofilms ◽

10.1017/s1479050508002251 ◽

2008 ◽

pp. 1-9

Author(s):

Y. Yang

Keyword(s):

Biofilm Formation ◽

Shewanella Oneidensis ◽

Glass Tube ◽

Biofilm Reactor ◽

Test Results ◽

Hydrodynamic Conditions ◽

Flow Conditions ◽

Pure Cultures ◽

Biofilm Development ◽

The Impact

ABSTRACTAlthough gravitational deposition is generally regarded to be important during biofilm development because it provides a mechanism by which bacteria can come into contact with a surface, this process is usually neglected in most biofilm studies. The purpose of this study was to develop a better understanding of the effect of gravitational deposition by comparing the development of biofilms on the upper and lower surfaces of a capillary glass tube biofilm reactor under various hydrodynamic conditions. Pure cultures ofPseudomonas fluorescensandShewanella oneidensisMR-1 were used for the test. Results demonstrated that gravitational deposition significantly influences biofilm development under slow laminar flow conditions, which may be attributable to the effect of gravity on both attachment and detachment during the initial reversible attachment phase and the later development phase. Additionally, it was shown that hydrodynamic conditions have the potential to reduce the impact of gravitational deposition on biofilm development, and that this became less significant with an increase in flow rate. These results will be useful for comparing biofilm development in different biofilm systems.

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Morphological Change and Decreasing Transfer Rate of Biofilm-Featured Listeria monocytogenes EGDe

Journal of Food Protection ◽

10.4315/0362-028x.jfp-16-226 ◽

2017 ◽

Vol 80 (3) ◽

pp. 368-375 ◽

Cited By ~ 2

Author(s):

Yuejia Lee ◽

Chinling Wang

Keyword(s):

Stainless Steel ◽

Listeria Monocytogenes ◽

Food Processing ◽

Biofilm Formation ◽

Transfer Rate ◽

Initial Level ◽

Foodborne Pathogen ◽

Bacterial Growth Rate ◽

Biofilm Development ◽

Food Processing Environment

ABSTRACT Listeria monocytogenes, a lethal foodborne pathogen, has the ability to resist the hostile food processing environment and thus frequently contaminates ready-to-eat foods during processing. It is commonly accepted that the tendency of L. monocytogenes' to generate biofilms on various surfaces enhances its resistance to the harshness of the food processing environment. However, the role of biofilm formation in the transferability of L. monocytogenes EGDe remains controversial. We examined the growth of Listeria biofilms on stainless steel surfaces and their effect on the transferability of L. monocytogenes EGDe. The experiments were a factorial 2 × 2 design with at least three biological replicates. Through scanning electron microscopy, a mature biofilm with intensive aggregates of cells was observed on the surface of stainless steel after 3 or 5 days of incubation, depending on the initial level of inoculation. During biofilm development, L. monocytogenes EGDe carried out binary fission vigorously before a mature biofilm was formed and subsequently changed its cellular morphology from rod shaped to sphere shaped. Furthermore, static biofilm, which was formed after 3 days of incubation at 25°C, significantly inhibited the transfer rate of L. monocytogenes EGDe from stainless steel blades to 15 bologna slices. During 7 days of storage at 4°C, however, bacterial growth rate was not significantly impacted by whether bacteria were transferred from biofilm and the initial concentrations of transferred bacteria on the slice. In conclusion, this study is the first to report a distinct change in morphology of L. monocytogenes EGDe at the late stage of biofilm formation. More importantly, once food is contaminated by L. monocytogenes EGDe, contamination proceeds independently of biofilm development and the initial level of contamination when food is stored at 4°C, even if contamination with L. monocytogenes EGDe was initially undetectable before storage.

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Biofilm Formation and Associated Genes in Listeria Monocytogenes

THE INDIAN JOURNAL OF VETERINARY SCIENCES AND BIOTECHNOLOGY ◽

10.21887/ijvsbt.v12i3.7079 ◽

2017 ◽

Vol 12 (3) ◽

Author(s):

S. R. Warke ◽

V. C. Ingle ◽

N. V. Kurkure ◽

P. A. Tembhurne ◽

Minakshi Prasad ◽

...

Keyword(s):

Public Health ◽

Listeria Monocytogenes ◽

Multiplex Pcr ◽

Food Processing ◽

Biofilm Formation ◽

Milk Samples ◽

Biofilm Production ◽

Food Borne ◽

Serious Infections ◽

Microtiter Assay

Listeria monocytogenes, an opportunistic food borne pathogen can cause serious infections in immunocompromised individuals. L. monocytogenes is capable of producing biofilm on the surface of food processing lines and instruments.The biofilm transfers contamination to food products and impose risk to public health. In the present study biofilm producing ability of L. monocytogenes isolates were investigated phenotypically and genotypically by microtiter assay and multiplex PCR, respectively. Out of 38 L. monocytogenes isolates 14 were recovered from animal clinical cases, 12 bovine environment and 12 from milk samples. A total of 3 (21.42%) clinical, 2 (16.66%) environment and 3 (25%) milk samples respectively, revealed biofilm production in microtiter assay. Cumulative results showed that 23 (60.52%) out of 38 strains of L. monocytogenes were positive for luxS and flaA gene and 1 (2.63%) was positive only for the flaA gene.

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Zero-Width Quasi-Sliding Mode Band in the Presence of Non-Matched Uncertainties

Energies ◽

10.3390/en14113011 ◽

2021 ◽

Vol 14 (11) ◽

pp. 3011

Author(s):

Paweł Latosiński ◽

Andrzej Bartoszewicz

Keyword(s):

Sliding Mode Control ◽

Discrete Time ◽

Sliding Mode ◽

Control Strategies ◽

Relative Degree ◽

Band Width ◽

Representative Point ◽

Mode Control ◽

Sliding Motion ◽

Selection Of

Sliding mode control strategies are well known for ensuring robustness of the system with respect to disturbance and model uncertainties. For continuous-time plants, they achieve this property by confining the system state to a particular hyperplane in the state space. Contrary to this, discrete-time sliding mode control (DSMC) strategies only drive the system representative point to a certain vicinity of that hyperplane. In established literature on DSMC, the width of this vicinity has always been strictly greater than zero in the presence of uncertainties. Thus, ideal sliding motion was considered impossible for discrete-time systems. In this paper, a new approach to DSMC design is presented with the aim of driving the system representative point exactly onto the sliding hyperplane even in the presence of uncertainties. As a result, the quasi-sliding mode band width is effectively reduced to zero and ideal discrete-time sliding motion is ensured. This is achieved with the proper selection of the sliding hyperplane, using the unique properties of relative degree two sliding variables. It is further demonstrated that, even in cases where selection of a relative degree two sliding variable is impossible, one can use the proposed technique to significantly reduce the quasi-sliding mode band width.

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