Hindering the formation and promoting the dispersion of medical biofilms: non-lethal effects of seagrass extracts

Abstract

BackgroundBiofilms have great significance in healthcare-associated infections owing to their inherent tolerance and resistance to antimicrobial therapies. New approaches to prevent and treat unwanted biofilms are urgently required. To this end, three seagrass species (Enhalus acoroides, Halophila ovalis and Halodule pinifolia) collected in Vietnam and in India were investigated for their effects in mediating non-lethal interactions on sessile bacterial (Escherichia coli) and fungal (Candida albicans) cultures. The present study was focused on anti-biofilm activities of seagrass extracts, without killing cells.MethodsMethanolic extracts were characterized, and major compounds were identified by MS/MS analysis. The antibiofilm properties of the seagrass extracts were tested at sub-lethal concentrations by using microtiter plate adhesion assay. The performance of the most promising extract was further investigated in elegant bioreactors to reproduce mature biofilms both at the solid/liquid and the solid/air interfaces. Dispersion and bioluminescent assays were carried out to decipher the mode of action of the bioactive extract.ResultsIt was shown that up to 100 ppm of crude extracts did not adversely affect microbial growth, nor do they act as a carbon and energy source for the selected microorganisms. Seagrass extracts appear to be more effective in deterring microbial adhesion on hydrophobic surfaces than on hydrophilic. The results revealed that non-lethal concentrations of E. acoroides leaf extract: i) reduce bacterial and fungal coverage by 60.9 and 73.9%, respectively; ii) affect bacterial biofilm maturation and promote dispersion, up to 70%, in fungal biofilm; iii) increase luminescence in Vibrio harveyi by 25.8%. The characterization of methanolic extracts showed the unique profile of the E. acoroides leaf extract.ConclusionsE. acoroides leaf extract proved to be the most promising extract among those tested. Indeed, the selected non-lethal concentrations of E. acoroides leaf extract were found to exert an antibiofilm effect on C. albicans and E. coli biofilm in the first phase of biofilm genesis, opening up the possibility of developing preventive strategies to hinder the adhesion of microbial cells to surfaces. The leaf extract also affected the dispersion and maturation steps in C. albicans and E. coli respectively, suggesting an important role in cell signaling processes.

Interactions with Microbial Proteins Driving the Antibacterial Activity of Flavonoids

“…However, it has been observed that biofilm-producing strains develop antibiotic resistance very fast, thus requiring the use of new antibacterial and antibiofilm compounds. Therefore, biofilms have a great impact on public health, causing about 65–80% of microbial diseases [ 107 ]. In this context, it has been reported that plant-derived extracts or isolated metabolites often exhibit good antibacterial and antibiofilm properties against several microorganisms.…”

Quercus infectoria gall extracts reduce quorum sensing-controlled virulence factors production and biofilm formation in Pseudomonas aeruginosa recovered from burn wounds

“…Biofilm is a population of microbes attached to surfaces and sustained by the secretion of an adhesive and protective matrix; biofilms are prevalent in nature, medical and other environments. Due to their inherent tolerance and resistance to antimicrobials, they have enormous implications in healthcare-related infections [44]. The biofilms produced by pathogenic bacteria may cause many health complaints in human, like cystic fibrosis, prostatitis, and periodontitis [45].…”

Biofilms—Impacts on Human Health and Its Relevance to Space Travel

“…The use of naturally derived plant-based extracts for antimicrobial and antibiofilm activity is steadily gaining traction in a variety of industries, not just due to their efficacious properties but also due to their less aggressive nature on sensitive surfaces and equipment when compared to sodium hydroxide, sodium hypochlorite, hydrogen peroxide, and other typical CIP treatments. A recent research article tested extracts from three species of sea grass ( Enhalus acoroides, Halophila ovalis, and Halodule pinifolia ) for their ability to prevent and remove clinically relevant biofilms [ 141 ]. All three leaf extracts showed a significant biofilm reduction capability against Escherichia coli and Candida albicans .…”