biofilm growth
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Author(s):  
Zhang Ye ◽  
Dina M. Silva ◽  
Daniela Traini ◽  
Paul Young ◽  
Shaokoon Cheng ◽  
...  

Abstract Biofilms are ubiquitous and notoriously difficult to eradicate and control, complicating human infections and industrial and agricultural biofouling. However, most of the study had used the biofilm model that attached to solid surface and developed in liquid submerged environments which generally have neglected the impact of interfaces. In our study, a reusable dual-chamber microreactor with interchangeable porous membranes was developed to establish multiple growth interfaces for biofilm culture and test. Protocol for culturing Pseudomonas aeruginosa (PAO1) on the air–liquid interface (ALI) and liquid–liquid interface (LLI) under static environmental conditions for 48 h was optimized using this novel device. This study shows that LLI model biofilms are more susceptible to physical disruption compared to ALI model biofilm. SEM images revealed a unique “dome-shaped” microcolonies morphological feature, which is more distinct on ALI biofilms than LLI. Furthermore, the study showed that ALI and LLI biofilms produced a similar amount of extracellular polymeric substances (EPS). As differences in biofilm structure and properties may lead to different outcomes when using the same eradication approaches, the antimicrobial effect of an antibiotic, ciprofloxacin (CIP), was chosen to test the susceptibility of a 48-h-old P. aeruginosa biofilms grown on ALI and LLI. Our results show that the minimum biofilm eradication concentration (MBEC) of 6-h CIP exposure for ALI and LLI biofilms is significantly different, which are 400 μg/mL and 200 μg/mL, respectively. These results highlight the importance of growth interface when developing more targeted biofilm management strategies, and our novel device provides a promising tool that enables manipulation of realistic biofilm growth. Key points • A novel dual-chamber microreactor device that enables the establishment of different interfaces for biofilm culture has been developed. • ALI model biofilms and LLI model biofilms show differences in resistance to physical disruption and antibiotic susceptibility.


Thorax ◽  
2022 ◽  
pp. thoraxjnl-2021-217576
Author(s):  
Mette Kolpen ◽  
Kasper Nørskov Kragh ◽  
Juan Barraza Enciso ◽  
Daniel Faurholt-Jepsen ◽  
Birgitte Lindegaard ◽  
...  

BackgroundA basic paradigm of human infection is that acute bacterial disease is caused by fast growing planktonic bacteria while chronic infections are caused by slow-growing, aggregated bacteria, a phenomenon known as a biofilm. For lung infections, this paradigm has been thought to be supported by observations of how bacteria proliferate in well-established growth media in the laboratory—the gold standard of microbiology.ObjectiveTo investigate the bacterial architecture in sputum from patients with acute and chronic lung infections.MethodsAdvanced imaging technology was used for quantification and direct comparison of infection types on fresh sputum samples, thereby directly testing the acute versus chronic paradigm.ResultsIn this study, we compared the bacterial lifestyle (planktonic or biofilm), growth rate and inflammatory response of bacteria in freshly collected sputum (n=43) from patient groups presenting with acute or chronic lung infections. We found that both acute and chronic lung infections are dominated by biofilms (aggregates of bacteria within an extracellular matrix), although planktonic cells were observed in both sample types. Bacteria grew faster in sputum from acute infections, but these fast-growing bacteria were enriched in biofilms similar to the architecture thought to be reserved for chronic infections. Cellular inflammation in the lungs was also similar across patient groups, but systemic inflammatory markers were only elevated in acute infections.ConclusionsOur findings indicate that the current paradigm of equating planktonic with acute and biofilm with chronic infection needs to be revisited as the difference lies primarily in metabolic rates, not bacterial architecture.


Author(s):  
Dena Z. Khater ◽  
R. S. Amin ◽  
Amani E. Fetohi ◽  
K. M. El-Khatib ◽  
Mohamed Mahmoud

Manganese oxide–silver nanocomposites anchored on graphitic mesoporous carbon were synthesized for enhancing oxygen reduction and inhibiting cathodic biofilm growth for the long-term operation of microbial fuel cells.


Processes ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 48
Author(s):  
Szymon Skoneczny ◽  
Monika Cioch-Skoneczny

This paper concerns the dynamical modeling of the microbiological processes that occur in the biofilms that are formed on fine inert particles. Such biofilm forms e.g. in fluidized-bed bio-reactors, expanded bed biofilm reactors and biofilm air-lift suspension reactors. An approximate model that is based on the Laplace–Carson transform and a family of approximate models that are based on the concept of the pseudo-stationary substrate concentration profile in the biofilm were proposed. The applicability of the models to the microbiological processes was evaluated following Monod or Haldane kinetics in the conditions of dynamical biofilm growth. The use of approximate models significantly simplifies the computations compared to the exact one. Moreover, the stiffness that was present in the exact model, which was solved numerically by the method of lines, was eliminated. Good accuracy was obtained even for large internal mass transfer resistances in the biofilm. It was shown that significantly higher accuracy was obtained using one of the proposed models than that which was obtained using the previously published approximate model that was derived using the homotopy analysis method.


Antibiotics ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 13
Author(s):  
Mathieu Nicolas ◽  
Bruno Beito ◽  
Marta Oliveira ◽  
Maria Tudela Martins ◽  
Bruno Gallas ◽  
...  

Nosocomial and medical device-induced biofilm infections affect millions of lives and urgently require innovative preventive approaches. These pathologies have led to the development of numerous antimicrobial strategies, an emergent topic involving both natural and synthetic routes, among which some are currently under testing for clinical approval and use. Antimicrobial peptides (AMPs) are ideal candidates for this fight. Therefore, the strategies involving surface functionalization with AMPs to prevent bacterial attachment/biofilms formation have experienced a tremendous development over the last decade. In this review, we describe the different mechanisms of action by which AMPs prevent bacterial adhesion and/or biofilm formation to better address their potential as anti-infective agents. We additionally analyze AMP immobilization techniques on a variety of materials, with a focus on biomedical applications. Furthermore, we summarize the advances made to date regarding the immobilization strategies of AMPs on various surfaces and their ability to prevent the adhesion of various microorganisms. Progress toward the clinical approval of AMPs in antibiotherapy is also reviewed.


2021 ◽  
Vol 8 (2) ◽  
pp. 119
Author(s):  
Diana Soesilo ◽  
Sinta Puspita ◽  
Phebe Fedora Christabel

ABSTRACTBackground: Streptococcus mutans in the most frequent microbiota that causes pulp necrosis because of caries. The microorganism that is colonized and embedded in the biofilm matrix is resistant to antimicrobials compared to planktonic cells. Root canal sterilization materials must have good biocompatibility with tissues. Nannochloropsis oculata is an algae that contains various compounds such as terpenoids, alkaloids, and flavonoids that have potential as antibacterial and antioxidant and can be used as alternative to root canal sterilization. Method: This research was true experimental laboratory research with post-test only control group design. The antibacterial potential of Nannochloropsis oculata was tested using the biofilm method, divided into 5 groups. The control group was: K- (aquadest), K+ (calcium hydroxide), and the treatment group was given Nannochloropsis oculata: P1 (0.625%), P2 (1.25%), and P3 (2.5 %). Congo Red method test was to determine the formation of biofilm that shows black strains on agar. While biofilm test with Microtiter Plate Assay to measure the value of biofilm that were inhibited in Optical Density (OD) value in the ELISA Reader. The lower the value, the more biofilm inhibited, with OD value, inhibition percentage could counted Result: The result of all treatment groups were increasing in percentage inhibition value shows inhibition in biofilm growth (p <0.05). Conclusion: Nannochloropsis oculata had an antibacterial effect on the biofilm of Streptococcus mutans


Author(s):  
Abhishek Naik ◽  
Mark Smithers ◽  
Pia H. Moisander

Marine biofilms are diverse microbial communities and important ecological habitats forming on surfaces submerged in the ocean. Biofilm communities resist environmental disturbance, making them a nuisance to some human activities (‘biofouling’). Anti-fouling solutions rarely address the underlying stability or compositional responses of these biofilms. Using bulk measurements and molecular analyses, we examined temporal and UV-C antifouling-based shifts in marine biofilms in the coastal Western North Atlantic Ocean during early fall. Over a 24-d period, bacterial communities shifted from early dominance of Gammaproteobacteria to increased proportions of Alphaproteobacteria, Bacteroidia and Acidimicrobiia. In a network analysis based on temporal covariance, Rhodobacteraceae (Alphaproteobacteria) nodes were abundant and densely connected with generally positive correlations. In the eukaryotic community, persistent algal, protistan, and invertebrate groups were observed, although consistent temporal succession was not detected. Biofilm UV-C treatment at 13 and 20 days resulted in losses of chlorophyll a and transparent exopolymer particles, indicating biomass disruption. Bacterial community shifts suggested that UV-C treatment decreased biofilm maturation rate and was associated with proportional shifts among diverse bacterial taxa. UV-C treatment was also associated with increased proportions of protists potentially involved in detritivory and parasitism. Older biofilm communities had increased resistance to UV-C, suggesting that early biofilms are more susceptible to UV-C based antifouling. The results suggest that UV-C irradiation is potentially an effective antifouling method in marine environments in terms of biomass removal and in slowing maturation. However, as they mature, biofilm communities may accumulate microbial members that are tolerant or resilient under UV-treatment. Importance Marine biofilms regulate processes from organic matter and pollutant turnover to eukaryotic settlement and growth. Biofilm growth and eukaryotic settlement interfering with human activities via growth on ship hulls, aquaculture operations, or other marine infrastructure are called ‘biofouling’. There is a need to develop sustainable anti-fouling techniques by minimizing impacts to surrounding biota. We use the biofouling-antifouling framework to test hypotheses about marine biofilm succession and stability in response to disturbance, using a novel UV-C LED device. We demonstrate strong bacterial biofilm successional patterns and detect taxa potentially contributing to stability under UV-C stress. Despite UV-C-associated biomass losses and varying UV susceptibility of microbial taxa, we detected high compositional resistance among biofilm bacterial communities, suggesting decoupling of disruption in biomass and community composition following UV-C irradiation. We also report microbial covariance patterns over 24 days of biofilm growth, pointing to areas for study of microbial interactions and targeted antifouling.


2021 ◽  
Vol 3 (12) ◽  
Author(s):  
Campbell W Gourlay ◽  
Fritz A Muhlschlegel ◽  
Daniel R Pentland

C. albicans is the predominant human fungal pathogen worldwide and frequently colonises medical devices, such as voice prosthesis, as a biofilm. It is a dimorphic yeast that can switch between yeast and hyphal forms in response to environmental cues, a property that is essential during biofilm establishment and maturation. One such cue is elevation of CO2 levels, as observed in exhaled breath for example. However, despite the clear medical relevance the effects of high CO2 levels on C. albicans biofilm growth has not been investigated to date. Here, we show that 5% CO2 significantly enhances each stage of the C. albicans biofilm forming process; from attachment through maturation to dispersion, via stimulation of the Ras/cAMP/PKA signalling pathway. Transcriptome analysis of biofilm formation under elevated CO2 conditions revealed the activation of key biofilm formation pathways governed by the central biofilm regulators Efg1, Brg1, Bcr1 and Ndt80. Biofilms grown in under elevated CO2 conditions also exhibit increases in azole resistance, tolerance to nutritional immunity and enhanced glucose uptake capabilities. We thus characterise the mechanisms by which elevated CO2 promote C. albicans biofilm formation. We also investigate the possibility of re-purposing drugs that can target the CO2 activated metabolic enhancements observed in C. albicans biofilms. Using this approach we can significantly reduce multi-species biofilm formation in a high CO2 environment and demonstrate a significant extension of the lifespan of voice prostheses in a patient trial. Our research demonstrates a bench to bedside approach to tackle Candida albicans biofilm formation.


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