Biofilm formation on contact surfaces contributes to persistence of foodborne pathogens all along the food and feed chain. The specific physiological features of bacterial cells embedded in biofilms ...contribute to their high tolerance to environmental stresses, including the action of antimicrobial compounds. As membrane lipid adaptation is a vital facet of bacterial response when cells are submitted to harsh or unstable conditions, we focused here on membrane fatty acid composition of biofilm cells as compared to their free-growing counterparts. Pathogenic bacteria (
Typhimurium) were cultivated in planktonic or biofilm states and membrane fatty acid analyses were performed on whole cells in both conditions. The percentage of saturated fatty acids increases in biofilm cells in all cases, with a concomitant decrease of branched-chain fatty acids for Gram-positive bacteria, or with a decrease in the sum of other fatty acids for Gram-negative bacteria. We propose that increased membrane saturation in biofilm cells is an adaptive stress response that allows bacteria to limit exchanges, save energy, and survive. Reprogramming of membrane fluidity in biofilm cells might explain specific biofilm behavior including bacterial recalcitrance to biocide action.
Editorial: Methods in biofilms: 2022 Briandet, Romain; Cerca, Nuno
Frontiers in cellular and infection microbiology,
08/2023, Letnik:
13, Številka:
2023
Journal Article
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Editorial on the Research Topic Methods in biofilms: 2022 Biofilms, complex communities of microorganisms adhering to surfaces, play a significant role in various fields, including healthcare, ...industry, and the environment (Flemming et al., 2016). As our understanding of biofilms expands, so does the need for advanced research methods and techniques to study their formation, composition, and physiological characteristics (Azeredo et al., 2017). This Research Topic aims to present a captivating collection of articles that highlight novel methodologies in biofilm research. Biofilms present researchers with a range of challenges and opportunities. The articles in this Research Topic address these challenges by focusing on the development and adaptation of cutting-edge methods for studying biofilms. By bridging the gap between different scientific disciplines, these contributions provide a comprehensive view of biofilm research. From investigating the dynamics of antibiotic resistance selection using microfluidic chips to the specific detection of multiple pathogens in co-infection and mixed biofilms, these articles offer valuable insights into the complex nature of biofilm formation and interactions. The Research Topic features articles that showcase innovative methodologies to study various aspects of biofilms. For instance, an article introduces a microfluidic chip for realtime monitoring of antibiotic resistance selection in bacterial biofilms (Tang et al.). This technology provides a valuable tool for understanding the dynamics of antibiotic resistance emergence and selection. Another article describes the development of a TaqMan duplex real-time PCR method for simultaneous detection of Streptococcus suis and Actinobacillus pleuropneumoniae in co-infection and mixed biofilms (Yi et al.). This method offers enhanced specificity and sensitivity for accurate quantification of these pathogens, facilitating disease prevention and control. Additionally, the Research Topic includes an upgraded repository of antimicrobial peptides (AMPs) for biofilm studies. This resource, B-AMP v2.0, provides a comprehensive collection of biofilm protein targets and AMPs, facilitating research into specific biofilm targets and anti-biofilm strategies (Ravichandran et al.). Furthermore, the utilization of fluorescence in situ hybridization (FISH) techniques is explored in another article, showcasing its applications for visualizing and quantifying microorganisms, genes, and metabolites within biofilms (Barbosa et al.). These advancements in FISH-based techniques offer valuable insights into biofilm structure Frontiers in Cellular and Infection Microbiology frontiersin.org 01
Few studies have extensively investigated probiotic functions associated with biofilms. Here, we show that strains of Lactobacillus plantarum and Lactobacillus fermentum are able to grow as biofilm ...on abiotic surfaces, but the biomass density differs between strains. We performed microtiter plate biofilm assays under growth conditions mimicking to the gastrointestinal environment. Osmolarity and low concentrations of bile significantly enhanced Lactobacillus spatial organization. Two L. plantarum strains were able to form biofilms under high concentrations of bile and mucus. We used the agar well-diffusion method to show that supernatants from all Lactobacillus except the NA4 isolate produced food pathogen inhibitory molecules in biofilm. Moreover, TNF-α production by LPS-activated human monocytoid cells was suppressed by supernatants from Lactobacillus cultivated as biofilms but not by planktonic culture supernatants. However, only L. fermentum NA4 showed anti-inflammatory effects in zebrafish embryos fed with probiotic bacteria, as assessed by cytokine transcript level (TNF-α, IL-1β and IL-10). We conclude that the biofilm mode of life is associated with beneficial probiotic properties of lactobacilli, in a strain dependent manner. Those results suggest that characterization of isolate phenotype in the biofilm state could be additional valuable information for the selection of probiotic strains.
•Lactobacillus biofilms increase resistance to gastrointestinal environment-related conditions.•Biofilm growth conditions increase the inhibition of pathogens growth and the lactobacilli immunomodulatory effects.•Zebrafish model allows the screening of probiotics with anti-inflammatory properties.
Biofilms are spatially organized communities of microorganisms embedded in a self-produced organic matrix, conferring to the population emerging properties such as an increased tolerance to the ...action of antimicrobials. It was shown that some bacilli were able to swim in the exogenous matrix of pathogenic biofilms and to counterbalance these properties. Swimming bacteria can deliver antimicrobial agents in situ, or potentiate the activity of antimicrobial by creating a transient vascularization network in the matrix. Hence, characterizing swimmer trajectories in the biofilm matrix is of particular interest to understand and optimize this new biocontrol strategy in particular, but also more generally to decipher ecological drivers of population spatial structure in natural biofilms ecosystems. In this study, a new methodology is developed to analyze time-lapse confocal laser scanning images to describe and compare the swimming trajectories of bacilli swimmers populations and their adaptations to the biofilm structure. The method is based on the inference of a kinetic model of swimmer populations including mechanistic interactions with the host biofilm. After validation on synthetic data, the methodology is implemented on images of three different species of motile bacillus species swimming in a Staphylococcus aureus biofilm. The fitted model allows to stratify the swimmer populations by their swimming behavior and provides insights into the mechanisms deployed by the micro-swimmers to adapt their swimming traits to the biofilm matrix.
Les microbes, on connaît leur existence depuis Pasteur. Pourtant, c'est depuis quelques années seulement qu'on les étudie sous leur forme d'organisation la plus répandue, celle de communautés fixées ...sur une surface: des biofilms. Les biofilms sont partout: dans le sol des forêts, sur les cailloux glissants des rivières, sur le verre des aquariums, sur la croûte fleurie du camembert, sur nos dents, où seul le détartrage les élimine, sur notre peau, où ils forment une barrière contre les microbes indésirables… Parfois, ils mettent notre santé en danger, causant des infections chroniques ou des maladies nosocomiales. Cependant, ils offrent aussi de multiples bénéfices, par exemple en protégeant naturellement les plantes, ou en permettant de nettoyer les eaux et les sols. Mais, direz-vous, quelle différence y a-t-il entre des microbes dispersés dans leur environnement et des biofilms? Quelles formes prennent ces biofilms, et quels microbes y trouve-t-on? Dans un style accessible et imagé, les auteurs nous font découvrir comment des microbes qui « dialoguent » entre eux, échangent des gènes et s'adaptent aux conditions d'une microsociété en perpétuelle évolution, acquièrent les étonnantes capacités de colonisation et de résistance caractéristiques des biofilms. Les chapitres sont illustrés par les talentueux dessins de Marion Jouffroy.
Bacteria grow in either planktonic form or as biofilms, which are attached to either inert or biological surfaces. Both growth forms are highly relevant states in nature and of paramount scientific ...focus. However, interchanges between bacteria in these two states have been little explored. We discovered that a subpopulation of planktonic bacilli is propelled by flagella to tunnel deep within a biofilm structure. Swimmers create transient pores that increase macromolecular transfer within the biofilm. Irrigation of the biofilm by swimmer bacteria may improve biofilm bacterial fitness by increasing nutrient flow in the matrix. However, we show that the opposite may also occur (i.e., swimmers can exacerbate killing of biofilm bacteria by facilitating penetration of toxic substances from the environment). We combined these observations with the fact that numerous bacteria produce antimicrobial substances in nature. We hypothesized and proved that motile bacilli expressing a bactericide can also kill a heterologous biofilm population, Staphylococcus aureus in this case, and then occupy the newly created space. These findings identify microbial motility as a determinant of the biofilm landscape and add motility to the complement of traits contributing to rapid alterations in biofilm populations.
Most cosmetic products are susceptible to microbiological spoilage due to contaminations that could happen during fabrication or by consumer's repetitive manipulation. The composition of cosmetic ...products must guarantee efficient bacterial inactivation all along with the product shelf life, which is usually assessed by challenge-tests. A challenge-test consists in inoculating specific bacteria, i.e. Staphylococcus aureus, in the formula and then investigating the bacterial log reduction over time. The main limitation of this method is relative to the time-consuming protocol, where 30 days are needed to obtain results. In this study, we have proposed a rapid alternative method coupling High Content Screening-Confocal Laser Scanning Microscopy (HCS-CLSM), image analysis and modeling. It consists in acquiring real-time S. aureus inactivation kinetics on short-time periods (typically 4h) and in predicting the efficiency of preservatives on longer scale periods (up to 7 days). The action of two preservatives, chlorphenesin and benzyl alcohol, was evaluated against S. aureus at several concentrations in a cosmetic matrix. From these datasets, we compared two secondary models to determine the logarithm reduction time (Dc) for each preservative concentration. Afterwards, we used two primary inactivation models to predict log reductions for up to 7 days and we compared them to observed log reductions. The IQ model better fits datasets and the Q value gives information about the matrix level of interference.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Abstract
Bacillus subtilis
can form various types of spatially organised communities on surfaces, such as colonies, pellicles and submerged biofilms. These communities share similarities and ...differences, and phenotypic heterogeneity has been reported for each type of community. Here, we studied spatial transcriptional heterogeneity across the three types of surface-associated communities. Using RNA-seq analysis of different regions or populations for each community type, we identified genes that are specifically expressed within each selected population. We constructed fluorescent transcriptional fusions for 17 of these genes, and observed their expression in submerged biofilms using time-lapse confocal laser scanning microscopy (CLSM). We found mosaic expression patterns for some genes; in particular, we observed spatially segregated cells displaying opposite regulation of carbon metabolism genes (
gapA
and
gapB
), indicative of distinct glycolytic or gluconeogenic regimes coexisting in the same biofilm region. Overall, our study provides a direct comparison of spatial transcriptional heterogeneity, at different scales, for the three main models of
B. subtilis
surface-associated communities.
Clostridioides difficile infection associated to gut microbiome dysbiosis is the leading cause for nosocomial diarrhea. The ability of C. difficile to form biofilms has been progressively linked to ...its pathogenesis as well as its persistence in the gut. Although C. difficile has been reported to form biofilms in an increasing number of conditions, little is known about how these biofilms are formed in the gut and what factors may trigger their formation. Here we report that succinate, a metabolite abundantly produced by the dysbiotic gut microbiota, induces in vitro biofilm formation of C. difficile strains. We characterized the morphology and spatial composition of succinate-induced biofilms, and compared to non-induced or deoxycholate (DCA) induced biofilms. Biofilms induced by succinate are significantly thicker, structurally more complex, and poorer in proteins and exopolysaccharides (EPS). We then applied transcriptomics and genetics to characterize the early stages of succinate-induced biofilm formation and we showed that succinate-induced biofilm results from major metabolic shifts and cell-wall composition changes. Similar to DCA-induced biofilms, biofilms induced by succinate depend on the presence of a rapidly metabolized sugar. Finally, although succinate can be consumed by the bacteria, we found that the extracellular succinate is in fact responsible for the induction of biofilm formation through complex regulation involving global metabolic regulators and the osmotic stress response. Thus, our work suggests that as a gut signal, succinate may drive biofilm formation and help persistence of C. difficile in the gut, increasing the risk of relapse.
Biofilm formation is a ubiquitous process of bacterial communities that enables them to survive and persist in various environmental niches. The Bacillus cereus group includes phenotypically ...diversified species that are widely distributed in the environment. Often, B. cereus is considered a soil inhabitant, but it is also commonly isolated from plant roots, nematodes, and food products. Biofilms differ in their architecture and developmental processes, reflecting adaptations to specific niches. Importantly, some B. cereus strains are foodborne pathogens responsible for two types of gastrointestinal diseases, diarrhea and emesis, caused by distinct toxins. Thus, the persistency of biofilms is of particular concern for the food industry, and understanding the underlying mechanisms of biofilm formation contributes to cleaning procedures. This review focuses on the genetic background underpinning the regulation of biofilm development, as well as the matrix components associated with biofilms. We also reflect on the correlation between biofilm formation and the development of highly resistant spores. Finally, advances in our understanding of the ecological importance and evolution of biofilm formation in the B. cereus group are discussed.
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