Synergy between Sophorolipid Biosurfactant and SDS Increases the Efficiency of P. aeruginosa Biofilm Disruption

Abstract

Biofilms are communities of bacteria encased in selfsecreted extracellular polymeric substances (EPS) that adhere stubbornly to submerged surfaces. Once established, these communities can cause serious chronic illnesses in medical settings, while they can promote corrosion and biofouling in industrial settings. Due to the difficulty of their removal, strongly oxidizing chemicals and detergents can be used to degrade and remove biofilms by killing the cells and degrading the matrix; however, the choice of compounds is limited in delicate environments due to the potential damage they may cause. In the case of detergents, most are synthesized from nonrenewable petrochemicals that have a degree of aquatic toxicity. There is a growing need to identify and characterize alternatives to synthetic surfactants. Biosurfactants, which are surfactants produced by microorganisms, are a promising alternative since they can be synthesized from renewable resources, have low environmental toxicity, and have been shown to have higher degrees of specificity in the mechanism of action. Sophorolipids are a class of glycolipid surfactants produced by yeast that have demonstrated great promise due to large yields from renewable feedstocks and for antimicrobial properties; however, the effect of the application of sophorolipids to Gramnegative bacterial biofilms has not been well studied. We investigate the antibiofilm properties of sophorolipids by demonstrating its ability to cause the catastrophic disruption of Pseudomonas aeruginosa PAO1 biofilms in microfluidic channels. We show that while sophorolipids inflict little damage to the bacteria, they weaken the EPS biofilm matrix, leading to surface-detachment and breakup of the biofilm. Furthermore, we find that sophorolipids act cooperatively with the widely used surfactant, sodium dodecyl sulfate. When combined, concentrations ∼100-fold lower than the minimum effective concentration, when used independently, recover potency. Biosurfactants are typically expensive to produce, thus our work demonstrates a means to improve efficacy while simultaneously reducing both cost and the amount of environmentally harmful substances used.

Natural Anti-biofilm Agents: Strategies to Control Biofilm-Forming Pathogens

“…L. rhamnosusderived biosurfactants cause cell lysis by disrupting the membrane structure, thus can be used as an anti-biofilm agent for multispecies biofilms on silicone devices, i.e., voice prostheses in case of laryngectomy (Tan et al, 2017). The anti-biofilm activity of biosurfactants can augment extensively in combination with caprylic acid that inhibits biofilm formation of P. aeruginosa, E. coli, and B. subtilis (Diaz De Rienzo et al, 2016); amphotericin B (AmB) or fluconazole synergistically acts against biofilm formation and preformed biofilm of C. albicans (Haque et al, 2016); and surfactants such as SDS led to the destruction of P. aeruginosa PAO1 biofilms (Nguyen et al, 2020).…”

Biosurfactants as Anticancer Agents: Glycolipids Affect Skin Cells in a Differential Manner Dependent on Chemical Structure

“…In recent decades, there have been a significant number of reports on the bioactivities of glycolipids. However, many of these reports either utilized poorly characterized, impure preparations or only a single class of glycolipids whose proportion and percentage purity may not have been reported [9,26,[44][45][46][47][48][49][50][51]. Therefore, in this study, to investigate the effects of microbial glycolipids with different chemical structures on skin cells, the congeners present in the glycolipid preparations utilized were first rigorously characterized.…”

Synthetic and biological surfactant effects on freshwater biofilm community composition and metabolic activity

“…Biofilm volume has also been reduced after a single surfactant exposure event, with decreases of 26.5-98.1% occurring between 22-48 hours after exposure (Mireles II et al ., 2001; Quinn et al ., 2013). However, previous work on surfactant effects have also shown that biofilms demonstrate resistance and can recover full respiratory activity 12 hours after the initial exposure (Simoes et al ., 2008) and biomass 5 hours after initial exposure (Nguyen et al ., 2020). Therefore, the length of our experiment of 32 days may have been long enough where GPP, CR, and AFDM could be stable over time, despite the permanent exposure.…”

“…However, previous work on surfactant effects have also shown that biofilms demonstrate resistance and can recover full respiratory activity 12 hours after the initial exposure (Simoes et al . 2008) and biomass 5 hours after initial exposure (Nguyen et al . 2020).…”

“…Research on the effects of surfactants on microbial biofilms has primarily focused on single-species environmental biofilms or those commonly found in medical and industrial environments. Direct applications of the anionic synthetic surfactant SDS has shown significant disruption of growth and development of Pseudomonas aeruginosa biofilms (Díaz De Rienzo et al ., 2016; Nguyen et al ., 2020). Exposure to SDS has also decreased biofilm density and flattened its shape (Robinson et al ., 2006).…”