Diverse Effects of Natural and Synthetic Surfactants on the Inhibition of Staphylococcus aureus Biofilm

Abstract

A major challenge in the biomedical field is the creation of materials and coating strategies that effectively limit the onset of biofilm-associated infections on medical devices. Biosurfactants are well known and appreciated for their antimicrobial/anti-adhesive/anti-biofilm properties, low toxicity, and biocompatibility. In this study, the rhamnolipid produced by Pseudomonas aeruginosa 89 (R89BS) was characterized by HPLC-MS/MS and its ability to modify cell surface hydrophobicity and membrane permeability as well as its antimicrobial, anti-adhesive, and anti-biofilm activity against Staphylococcus aureus were compared to two commonly used surfactants of synthetic origin: Tween® 80 and TritonTM X-100. The R89BS crude extract showed a grade of purity of 91.4% and was composed by 70.6% of mono-rhamnolipids and 20.8% of di-rhamnolipids. The biological activities of R89BS towards S. aureus were higher than those of the two synthetic surfactants. In particular, the anti-adhesive and anti-biofilm properties of R89BS and of its purified mono- and di-congeners were similar. R89BS inhibition of S. aureus adhesion and biofilm formation was ~97% and 85%, respectively, and resulted in an increased inhibition of about 33% after 6 h and of about 39% after 72 h when compared to their chemical counterparts. These results suggest a possible applicability of R89BS as a protective coating agent to limit implant colonization.

Evaluation of Antimicrobial Properties and Potential Applications of Pseudomonas gessardii M15 Rhamnolipids towards Multiresistant Staphylococcus aureus

“…On the other hand, the best results were achieved by the mixture composed only of mono-RLs, M15RL. This is in accordance with the literature, suggesting that mono-RLs are more efficient than di-RLs in killing S. aureus [ 37 , 38 ]. In addition, M15RL contained a higher relative abundance of mono-RLs bearing β-hydroxy fatty acids with chain lengths greater than C10, as compared to the MDRL mixture.…”

Rhamnolipid 89 Biosurfactant Is Effective against Streptococcus oralis Biofilm and Preserves Osteoblast Behavior: Perspectives in Dental Implantology

“…After acidification at pH 2.2 with 6M H 2 SO 4 and storage overnight at 4 °C, R89BS was finally extracted three times with ethyl acetate (Merck KGaA, Darmstadt, Germany) and the organic phase was evaporated to dryness under vacuum conditions. The composition of R89BS by mass spectrometry analysis was previously reported in Allegrone et al [ 27 ].…”

“…More recently, we tested for the first time the in vitro efficacy of a rhamnolipid coating on different commercial titanium surfaces against microbial colonization [ 21 , 26 ]. The rhamnolipid 89 biosurfactant (R89BS), composed by 70.6% of mono-rhamnolipids and 20.8% of di-rhamnolipids with a 91.4% purity grade [ 27 ], when coated to titanium, acted as an efficient antiadhesive agent, significantly inhibiting the formation of both single ( Staphylococcus aureus and Staphylococcus epidermidis ) and bacterial/fungal ( S. aureus / Candida albicans ) dual biofilms, limiting both biofilm biomass and microorganisms’ metabolic activity [ 21 , 26 ]. Experiments addressing the biocompatibility showed the eluate from R89BS-coated titanium discs was non-cytotoxic for both fibroblasts [ 21 ] and osteoblasts [ 26 ].…”

Recent Strategies to Combat Biofilms Using Antimicrobial Agents and Therapeutic Approaches

“…Triton X-100 and Tween 80 (Polysorbate 80) are the two popular non-ionic, synthetically derived, and regularly used surfactants in laboratories ( Table 2 ). Tween 80 decreased S. aureus medical device associated biofilm development at concentrations safe in humans [ 30 ]. Triton X-100 could stimulate autolysis by enhancing bacterial vulnerability to antibiotics and altering the architecture and physiological features of biofilms by reducing the protein and carbohydrate constitution in the EPS [ 31 , 32 ].…”