Rhamnolipids from <i>Pseudomonas aeruginosa</i> Rn19a Modifies the Biofilm Formation over a Borosilicate Surface by Clinical Isolates

• Main Authors: Jair Carrazco-Palafox, Blanca Estela Rivera-Chavira, Jaime Raúl Adame-Gallegos, Luz María Rodríguez-Valdez, Erasmo Orrantia-Borunda, Guadalupe Virginia Nevárez-Moorillón
• Format: Article
• Language: English
• Published: MDPI AG 2021-01-01
• Series: Coatings
• Subjects: <i>Pseudomonas aeruginosa</i>; rhamnolipids; biofilms; microbial adhesion; bioreactor; borosilicate surface
• Online Access: https://www.mdpi.com/2079-6412/11/2/136

Microbial cells are reversibly associated with surfaces in the form of biofilms. Adhesion is the mechanism used by the microorganisms to bind to a surface initially; no biofilm is formed without the initial adhesion. The aim of this work was to evaluate the efficacy of the rhamnolipids of <i>Pseudomonas aeruginosa</i> Rn19a in inhibiting the biofilms formed by the clinical isolates <i>Escherichia coli</i> I5<i>, Pseudomonas aeruginosa</i> E26, <i>Enterococcus faecalis</i> I27 on borosilicate coupons inside a Center for Disease Control and Prevention (CDC) reactor. The isolate E26 (<i>P. aeruginosa</i>) did not show an adverse effect on biofilm formation by the rhamnolipid presence and showed normal growth in all the conditions tested (dynamic and static growth). The <i>Enterococcus faecalis</i> I27 isolate decreased its biofilm formation ability in 2.2 log CFU/cm² in static conditions by the addition of rhamnolipids and 3.0 log units in dynamic conditions. Finally, the <i>E. coli</i> I5 isolate was more susceptible to the influence of the borosilicate coupon covered with rhamnolipids. E5 reduced its biofilm formation capacity by 3.0 log CFU/cm² units at static conditions by the rhamnolipid addition and 6.0 log units at dynamic conditions. Biofilm formation was also observed by Confocal Laser Scanning Microscopy. In summary, the application of rhamnolipids may be useful to prevent the initial adhesion of bacteria to borosilicate surfaces. At a minimum, rhamnolipids effectively inhibit or diminish adhesion to surfaces by biofilm-forming isolates that do not belong to the genus <i>Pseudomonas</i>.