Pathogenic microbial biofilm, a consortium of microbial cells protected by a self-produced polymer matrix, is considered a worldwide challenge due to the inherent antibiotic resistance conferred by ...its lifestyle. Living, as it does, in a community of microbial organisms in a clinical situation, makes it responsible for severe and dangerous cases of infection. Combating this organisation of cells usually requires high antibiotic doses for a prolonged time, and these approaches often fail, contributing to infection persistence. In addition to therapeutic limitations, biofilms can be a source of infections when they grow in medical devices. The challenge imposed by biofilms has mobilised researchers in the entire world to prospect or develop alternatives to control biofilms. In this context, this review summarises the new frontiers that could be used in clinical circumstances in order to prevent or eliminate pathogenic biofilms.
Many bacteria have the capability to form a three-dimensional, strongly adherent network called 'biofilm'. Biofilms provide adherence, resourcing nutrients and offer protection to bacterial cells. ...They are involved in pathogenesis, disease progression and resistance to almost all classical antibiotics. The need for new antimicrobial therapies has led to exploring applications of gold and silver nanoparticles against bacterial biofilms. These nanoparticles and their respective ions exert antimicrobial action by damaging the biofilm structure, biofilm components and hampering bacterial metabolism via various mechanisms. While exerting the antimicrobial activity, these nanoparticles approach the biofilm, penetrate it, migrate internally and interact with key components of biofilm such as polysaccharides, proteins, nucleic acids and lipids via electrostatic, hydrophobic, hydrogen-bonding, Van der Waals and ionic interactions. Few bacterial biofilms also show resistance to these nanoparticles through similar interactions. The nature of these interactions and overall antimicrobial effect depend on the physicochemical properties of biofilm and nanoparticles. Hence, study of these interactions and participating molecular players is of prime importance, with which one can modulate properties of nanoparticles to get maximal antibacterial effects against a wide spectrum of bacterial pathogens. This article provides a comprehensive review of research specifically directed to understand the molecular interactions of gold and silver nanoparticles with various bacterial biofilms.
Biofilms are surface-associated bacterial communities that play both beneficial and harmful roles in nature, medicine, and industry. Tolerant and persister cells are thought to underlie ...biofilm-related bacterial recurrence in medical and industrial contexts. Here, we review recent progress aimed at understanding the mechanical features that drive biofilm resilience and the biofilm formation process at single-cell resolution. We discuss findings regarding mechanisms underlying bacterial tolerance and persistence in biofilms and how these phenotypes are linked to antibiotic resistance. New strategies for combatting tolerance and persistence in biofilms and possible methods for biofilm eradication are highlighted to inspire future development.
Biofilms are surface-associated bacterial communities that play both beneficial and harmful roles in nature, medicine, and industry. Here, we review recent progress aimed at understanding the mechanical features that drive biofilm resilience and the mechanisms underlying why biofilm-dwelling cells are tolerant and persistent to antibiotic treatment.
► The membrane biofilm reactor (MBfR) is introduced. ► The fundamental behavior of MBfRs is discussed. ► Current and novel applications are critically reviewed. ► Design and scale-up issues are ...presented. ► Key research needs are provided.
The membrane biofilm reactor (MBfR), an emerging technology for water and wastewater treatment, is based on pressurized membranes that supply a gaseous substrate to a biofilm formed on the membrane’s exterior. MBfR biofilms behave differently from conventional biofilms due to the counter-diffusion of substrates. MBfRs are uniquely suited for numerous treatment applications, including the removal of carbon and nitrogen when oxygen is supplied, and reduction of oxidized contaminants when hydrogen is supplied. Major benefits include high gas utilization efficiency, low energy consumption, and small reactor footprints. The first commercial MBfR was recently released, and its success may lead to the scale-up of other applications. MBfR development still faces challenges, including biofilm management, the design of scalable reactor configurations, and the identification of cost-effective membranes. If future research and development continue to address these issues, the MBfR may play a key role in the next generation of sustainable treatment systems.
Aims
The study aimed to perform a systematic investigation of the effects of quercetin on biofilm formation and virulence factors in Pseudomonas aeruginosa.
Methods and Results
The Ps. aeruginosa ...strain PAO1 was selected as the test strain. The results indicated that quercetin did not impact the growth of PAO1 as determined by MIC and growth curve analysis. However, this compound significantly inhibited (P < 0·05) biofilm formation and production of virulence factors including pyocyanin, protease and elastase at a lower concentration than those for most previously reported plant extracts and substances. Considering the central role of quorum sensing (QS) in the regulation of biofilm and virulence factor, we further detected the transcriptional changes associated with QS and found that the expression levels of lasI, lasR, rhlI and rhlR were significantly reduced (P < 0·05) by 34, 68, 57 and 50%, respectively, in response to 16 μg ml−1 quercetin.
Conclusions
This study indicated that quercetin is an effective inhibitor of biofilm formation and virulence factors in Ps. aeruginosa.
Significance and Impact of the Study
This is the first study to demonstrate that quercetin is an effective inhibitor of QS, biofilm formation and virulence factors in Ps. aeruginosa. Furthermore, quercetin might have potential in fighting biofilm‐related infections.
Air-based atmospheric-pressure plasma is an effective non-thermal method in deactivating various kinds of microbial biofilms with several advantages, including high bactericidal efficiency and low ...treatment costs. Bacterial biofilm formation is a major determinant in establishment of bacterial infection and also resistance to antibacterial chemotherapy. This study aims to assess the anti-biofilm potential of air-based atmospheric-pressure DBD plasma against
Staphylococcus aureus
and
Escherichia coli
biofilms. The biofilms of
Staphylococcus aureus
and
Escherichia coli
were exposed to air-based atmospheric-pressure DBD plasma for up to 4 min (control, 30 s, 90 s, 3 min, and 4 min) and their biofilm formation level, viability, and membrane integrity were determined. Based on the results, plasma exposure caused disruption up to 70% and 85% for
S. aureus
and
E. coli
biofilms, respectively. The biofilm disruption potential of air-based atmospheric-pressure DBD plasma was confirmed using the scanning electron microscopy (SEM). Besides, based on confocal laser scanning microscopy (CLSM), plasma exposure caused a significant bacterial inactivation and
E. coli
was found as more susceptible strain than
S. aureus.
In conclusion, atmospheric-pressure DBD plasma could be considered an efficient non-thermal approach against bacterial pathogenicity by biofilm disruption and thus prevention of infection establishment.
Microplastics are frequently detected in freshwater environments, serving as a new factitious substrate for colonization of biofilm-forming microorganisms. Distinct microbial assemblages between ...microplastics and surrounding waters have been well documented; however, there is insufficient knowledge regarding biofilm colonization of plastic and non-plastic substrates, despite the fact that microbial communities generally aggregate on natural solid surfaces. In this study, the effects of substrate type on microbial communities were evaluated by incubation of biofilms on microplastic substrates (polyethylene and polypropylene) and natural substrates (cobblestone and wood) for 21 days under controlled conditions. Results from high-throughput sequencing of 16S rRNA revealed that the alpha diversity (richness, evenness, and diversity) was lower in the microplastic-associated communities than in those on the natural substrates, indicating substrate-type-coupled species sorting. Distinct community structure and biofilm composition were observed between these two substrate types. Significantly higher abundances of Pirellulaceae, Phycisphaerales, Cyclobacteriaceae, and Roseococcus were observed on the microplastic substrates compared with the natural substrates. Simultaneously, the functional profiles (KEGG) predicted by Tax4Fun showed that the pathways of amino acid metabolism and metabolism of cofactors and vitamins were increased in biofilms on the microplastic substrates. The findings illustrate that microplastic acts as a distinct microbial habitat (compared with natural substrates) that could not only change the community structure but also affect microbial functions, potentially impacting the ecological functions of microbial communities in aquatic ecosystems.
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•Alpha diversity of biofilms was lower on microplastic than on natural substrates.•Community structure and composition varied between biofilms on different substrates.•Metabolic pathways were altered in biofilms colonizing microplastic.•Microplastic is a new microbial niche affecting microbial structure and function.•This alteration in biofilms may have an ecological impact on aquatic ecosystems.
The ubiquitous divalent cations magnesium and calcium are important nutrients required by bacteria for growth and cell maintenance. Multi-faceted roles are shown both in bacterial initial attachment ...and biofilm maturation. The effects of calcium and magnesium can be highlighted in physio-chemical interactions, gene regulation and bio-macromolecular structural modification, which lead to either promotion or inhibition of biofilms. This review outlines recent research addressing phenotypic changes and mechanisms undertaken by calcium and magnesium in affecting bacterial biofilm formation.
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