Advanced Research on Microbial Biofilms—a Themed Issue in Honor of Professor Gianfranco Donelli

A special issue of Microorganisms (ISSN 2076-2607). This special issue belongs to the section "Biofilm".

Deadline for manuscript submissions: 30 April 2025 | Viewed by 3142

Special Issue Editors


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Guest Editor
Laboratory for Skin Research, Galilee Medical Center, Nahariya, Israel
Interests: biofilms; antibiofilm agents; medical implant infections; acne

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Guest Editor
1. 5D Health Protection Group, Liverpool, UK
2. School of Biological Sciences, The University of Manchester, Manchester, UK
Interests: biofilm

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Guest Editor
Department of Biochemical Sciences for Health, University of Milan, Milan, Italy
Interests: microbiota and probiotics; prosthetic and joint infections; biofilm implant related infections; osteomyelitis; diagnosis for bone-joint infec-tions; antimicrobials and antimicrobial devices
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Special Issue Information

Dear Colleagues,

It is our pleasure to announce a Special Issue of Microorganisms in honor of Professor Gianfranco Donelli, a pioneer in the field of microbial biofilms. Professor Donelli received a master’s degree in biology from the Sapienza University of Rome in 1966. Beginning in 1967, he carried out research at the Istituto Superiore di Sanità (ISS—Italian National Institute of Health) in Rome. He began working in the field of molecular biology and ultrastructure of bacteriophages and human intestinal viruses. In 1975 he was appointed Director of the Electron Microscopy Unit and in 1979 he became the Research Director in molecular biology. From 1982–1996 he led the Laboratory of Ultrastructures of ISS. During those years his main research interest was microbiology with an emphasis on the mechanism of action and pathogenesis of toxins and other bacterial virulence factors. Professor Donelli served as Director of the Microbial Biofilm Laboratory at the Fondazione Santa Lucia research hospital in Rome from 2000–2022, during which time his research focused on biofilm-related healthcare-associated infections and strategies to prevent the development of microbial biofilms in the human body.

Professor Donelli is one of the leading biomedical scientists in Italy. He has authored of more than 200 full-length papers which have been cited more than 14,500 times. He has also edited numerous books and arranged numerous meetings and workshops in the field of microbial biofilms.

In recognition of Prof. Donelli’s scientific and educational contributions to the field, this Special Issue welcomes the submission of original research manuscripts or review articles on all aspects of microbial biofilms. We look forward to receiving your contributions.

Dr. Jeffrey B. Kaplan
Dr. Steven L. Percival
Dr. Lorenzo Drago
Guest Editors

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Keywords

  • microbial biofilms
  • antibiofilm
  • biofilm development
  • evolution of biofilms

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Published Papers (4 papers)

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Research

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23 pages, 2714 KiB  
Article
Investigating the Potential of L(+)-Lactic Acid as a Green Inhibitor and Eradicator of a Dual-Species Campylobacter spp. Biofilm Formed on Food Processing Model Surfaces
by Dimitra Kostoglou, Martha Apostolopoulou, Athina Lagou, Spyros Didos, Anagnostis Argiriou and Efstathios Giaouris
Microorganisms 2024, 12(11), 2124; https://doi.org/10.3390/microorganisms12112124 - 23 Oct 2024
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Abstract
Campylobacter spp. are prevalent foodborne bacterial enteric pathogens. Their inclusion in biofilms on abiotic surfaces is considered a strategy that facilitates their extraintestinal survival. Organic acid (OA) treatments could be used in a green approach to decontaminate various surfaces. This work aimed to [...] Read more.
Campylobacter spp. are prevalent foodborne bacterial enteric pathogens. Their inclusion in biofilms on abiotic surfaces is considered a strategy that facilitates their extraintestinal survival. Organic acid (OA) treatments could be used in a green approach to decontaminate various surfaces. This work aimed to evaluate the inhibitory and eradicative effects of L(+)-lactic acid (LA), a naturally occurring OA, on a dual-species biofilm formed on two food processing model surfaces (polystyrene and stainless steel) by three selected foodborne Campylobacter spp. isolates (two C. jejuni and one C. coli). The influence of aerobiosis conditions (microaerophilic, aerobic and CO2 enriched) on the resistance of the established biofilms to the acid was also tested. In parallel, the predominant metabolites contained in the planktonic media of biofilm monocultures and mixed-culture biofilm were comparatively analyzed by an untargeted metabolomics approach. Results revealed that LA inhibited mixed-culture biofilm formation by more than 2 logs (>99%) on both surfaces when this was applied at its highest tested concentration (4096 μg/mL; 0.34% v/v). However, all the preformed mixed-culture biofilms (ca. 106−7 CFU/cm2) could not be eradicated even when the acid was used at concentrations exceeding 5% v/v, denoting their extremely high recalcitrance which was still influenced by the abiotic substratum, and the biofilm-forming aerobiosis conditions. The metabolic analysis revealed a strain-specific metabolite production which might also be related to the strain-specific biofilm-forming and resistance behaviors and resulted in the distinct clustering of the different samples. Overall, the current findings provide important information on the effectiveness of LA against biofilm campylobacteria and may assist in mitigating their risk in the food chain. Full article
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15 pages, 2229 KiB  
Article
Role of the SaeRS Two-Component Regulatory System in Group B Streptococcus Biofilm Formation on Human Fibrinogen
by Francesco Coppolino, Alessia Berbiglia, Germana Lentini, Agata Famà, Giampiero Pietrocola, Giuseppe Teti, Concetta Beninati and Giuseppe Valerio De Gaetano
Microorganisms 2024, 12(10), 2096; https://doi.org/10.3390/microorganisms12102096 - 20 Oct 2024
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Abstract
Streptococcus agalactiae, also known as Group B Streptococcus or GBS, is a commensal colonizer of human vaginal and gastrointestinal tracts that can also be a deadly pathogen for newborns, pregnant women, and the elderly. The SaeRS two-component regulatory system (TCS) positively regulates [...] Read more.
Streptococcus agalactiae, also known as Group B Streptococcus or GBS, is a commensal colonizer of human vaginal and gastrointestinal tracts that can also be a deadly pathogen for newborns, pregnant women, and the elderly. The SaeRS two-component regulatory system (TCS) positively regulates the expression of two GBS adhesins genes, but its role in the formation of biofilm, an important step in pathogenesis, has not been investigated. In the present study, we set up a novel model of GBS biofilm formation using surfaces coated with human fibrinogen (hFg). Biofilm mass and structure were analyzed by crystal violet staining and three-dimensional fluorescence microscopy, respectively. GBS growth on hFg resulted in the formation of a mature and abundant biofilm composed of bacterial cells and an extracellular matrix containing polysaccharides, proteins, and extracellular DNA (eDNA). Enzymatic and genetic analysis showed that GBS biofilm formation on hFg is dependent on proteins and eDNA in the extracellular matrix and on the presence of covalently linked cell wall proteins on the bacterial surface but not on the type-specific capsular polysaccharide. In the absence of the SaeR regulator of the SaeRS TCS, there was a significant reduction in biomass formation, with reduced numbers of bacterial cells, reduced eDNA content, and disruption of the biofilm architecture. Overall, our data suggest that GBS binding to hFg contributes to biofilm formation and that the SaeRS TCS plays an important role in this process. Full article
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15 pages, 2487 KiB  
Article
Antibacterial and Antibiofilm Effects of L-Carnitine-Fumarate on Oral Streptococcal Strains Streptococcus mutans and Streptococcus sobrinus
by Anna Goc, Waldemar Sumera, Matthias Rath and Aleksandra Niedzwiecki
Microorganisms 2024, 12(8), 1613; https://doi.org/10.3390/microorganisms12081613 - 7 Aug 2024
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Abstract
Streptococcus mutans is a major pathogenic habitant of oral caries. Owing to its physiological and biochemical features, it prevails in the form of plaque biofilm together with another important mutans streptococci species, Streptococcus sobrinus. Both species are considered as initiators of cavity [...] Read more.
Streptococcus mutans is a major pathogenic habitant of oral caries. Owing to its physiological and biochemical features, it prevails in the form of plaque biofilm together with another important mutans streptococci species, Streptococcus sobrinus. Both species are considered as initiators of cavity lesions, and biofilm is essential to the dental caries process. Compared with the planktonic populations, the biofilm form has higher resistance to environmental conditions and antibiotics. Dental plaques also secure the long-term survival of microorganisms and protection from any stress conditions. To address the need for new antibiofilm agents, we have focused on L-carnitine-fumarate, a fumarate-conjugated quaternary ammonium compound. Using the macro-broth susceptibility testing method, we established its MIC value as 6.0 mg/mL. The MBC value, determined from the broth dilution minimum inhibitory concentration test by sub-culturing it to BHI agar plates, was established as 7.0 mg/mL. Antibiofilm efficacy was tested in 96-well plates coated with saliva using BHI broth supplemented with 1% sucrose as a standard approach. The obtained results allowed us to assess the MIBC as 7.5 mg/mL and the MBBC value as 10.0 mg/mL. The latter concentration also caused approximately 20% eradication of pre-existing biofilm. EPS-rich matrix, forming the core of the biofilm and enabling a confined acidic microenvironment, was also examined and confirmed the effectiveness of 10.0 mg/mL L-carnitine-fumarate concentration in inhibiting EPS formation. Furthermore, the anti-adherent and anti-aciduric impacts of L-carnitine-fumarate were investigated and revealed significant inhibitory effects at sub-MIC concentrations. The influence of L-carnitine-fumarate on the phosphotransferase system was investigated as well. Our results provide a new insight into the antibacterial potential of L-carnitine-fumarate as a valuable compound to be considered for alternative or adjunct anti-caries and antibiofilm preventive approaches. Full article
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Review

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14 pages, 10504 KiB  
Review
Pseudomonas aeruginosa in the Frontline of the Greatest Challenge of Biofilm Infection—Its Tolerance to Antibiotics
by Niels Høiby, Claus Moser and Oana Ciofu
Microorganisms 2024, 12(11), 2115; https://doi.org/10.3390/microorganisms12112115 - 22 Oct 2024
Viewed by 451
Abstract
P. aeruginosa biofilms are aggregates of bacteria surrounded by a self-produced matrix which binds to some antibiotics such as aminoglycosides. P. aeruginosa biofilms are tolerant to antibiotics. The treatment of biofilm infections leads to a recurrence of symptoms after finishing antibiotic treatment, although [...] Read more.
P. aeruginosa biofilms are aggregates of bacteria surrounded by a self-produced matrix which binds to some antibiotics such as aminoglycosides. P. aeruginosa biofilms are tolerant to antibiotics. The treatment of biofilm infections leads to a recurrence of symptoms after finishing antibiotic treatment, although the initial clinical response to the treatment is frequently favorable. There is a concentration gradient of oxygen and nutrients from the surface to the center of biofilms. Surface-located bacteria are multiplying and metabolizing, whereas deeper located bacteria are dormant and tolerant to most antibiotics. Colistin kills dormant bacteria, and combination therapy with colistin and antibiotics which kills multiplying bacteria is efficient in vitro. Some antibiotics such as imipenem induce additional production of the biofilm matrix and of chromosomal beta-lactamase in biofilms. Biofilms present a third Pharmacokinetic/Pharmacodynamic (PK/PD) micro-compartment (first: blood, second: tissue, third: biofilm) which must be taken into consideration when calculations try to predict the antibiotic concentrations in biofilms and thereby the probability of target attainment (PTA) for killing the biofilm. Treating biofilms with hyperbaric oxygen to wake up the dormant cells, destruction of the biofilm matrix, and the use of bacteriophage therapy in combination with antibiotics are promising possibilities which have shown proof of concept in in vitro experiments and in animal experiments. Full article
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