Use of Quorum Sensing Inhibition Strategies to Control Microfouling

Abstract

Interfering with the quorum sensing bacterial communication systems has been proposed as a promising strategy to control bacterial biofilm formation, a key process in biofouling development. Appropriate in vitro biofilm-forming bacteria models are needed to establish screening methods for innovative anti-biofilm and anti-microfouling compounds. Four marine strains, two Pseudoalteromonas spp. and two Vibrio spp., were selected and studied with regard to their biofilm-forming capacity and sensitivity to quorum sensing (QS) inhibitors. Biofilm experiments were performed using two biofilm cultivation and quantification methods: the xCELLigence® system, which allows online monitoring of biofilm formation, and the active attachment model, which allows refreshment of the culture medium to obtain a strong biofilm that can be quantified with standard staining methods. Although all selected strains produced acyl-homoserine-lactone (AHL) QS signals, only the P. flavipulchra biofilm, measured with both quantification systems, was significantly reduced with the addition of the AHL-lactonase Aii20J without a significant effect on planktonic growth. Two-species biofilms containing P. flavipulchra were also affected by the addition of Aii20J, indicating an influence on the target bacterial strain as well as an indirect effect on the co-cultured bacterium. The use of xCELLigence® is proposed as a time-saving method to quantify biofilm formation and search for eco-friendly anti-microfouling compounds based on quorum sensing inhibition (QSI) strategies. The results obtained from these two in vitro biofilm formation methods revealed important differences in the response of biosensor bacteria to culture medium and conditions, indicating that several strains should be used simultaneously for screening purposes and the cultivation conditions should be carefully optimized for each specific purpose.

Evaluation of the Anti-fouling Efficacy of Bacillus licheniformis Extracts Under Environmental and Natural Conditions

“…Then, 180 µl of each culture were added into E-Plates 16 (Agilent Technologies Inc., Santa Clara, CA, United States) and supplemented with 20 µl of B. licheniformis extracts. The system was incubated at 22 • C for 44 h. As controls, the un-inoculated TSB medium and the culture of biosensor biofilm-forming bacteria with 20 µl of PBS were used (Muras et al, 2021a). Experiments were performed in triplicate.…”

“…Two Vibrio strains (V. aestuarianus and V. tubiashii) and two Pseudoalteromonas strains (P. flavipulchra and P. maricaloris) were selected to test the biofilm inhibitory activity of different B. licheniformis extracts. These marine strains were chosen based on their ability to form robust biofilms as detected by the xCELLigence real-time biofilm monitoring system, presenting different sensitivity to quorum sensing (QS) inhibitors and being able to form biofilm in a wide range of salinities (Muras et al, 2021a).…”

“…The presence of multiple antibiofilm and anti-fouling compounds with complementary activities in B. licheniformis strains and the increasing interest in the search for new ecofriendly anti-fouling compounds intrigued us to test the capacity of extracts of the type strain B. licheniformis NCTC 10341 T to prevent fouling under natural conditions. The strain was selected in a preliminary screening experiment in which the anti-biofilm activity of several compounds and bacterial strains against marine bacteria was tested (Muras et al, 2021a). The use of extracts was preferred due to lower production cost, and to take profit of the probable presence of multiple active compounds in the same extract.…”

“…The use of extracts was preferred due to lower production cost, and to take profit of the probable presence of multiple active compounds in the same extract. In a preliminary phase, and in order to select the most suitable extract for field trials, the anti-biofilm activity of different B. licheniformis extracts was assessed using different marine bacteria selected as models for marine biofilm formation and measured using the real-time equipment xCELLigence R System RTCA DP (Agilent Technologies Inc., Santa Clara, CA, United States) (Muras et al, 2021a). Furthermore, the anti-macrofouling efficacy against model organisms, including the bryozoan Bugula neritina and the barnacle Amphibalanus amphitrite, was examined.…”

Biocontrol of Biofilm Formation: Jamming of Sessile-Associated Rhizobial Communication by Rhodococcal Quorum-Quenching

“…As QS is essential for biofilm installation and development, disrupting the flow of signals between biofilm members by a quorum-quenching (QQ) mechanism appears to be a promising method of control [ 21 , 22 , 23 , 24 , 25 , 26 , 27 ]. This possible application of QQ first emerged in the clinical context [ 21 , 22 , 23 , 24 ] and in the field of anti-biofouling [ 25 , 26 , 27 , 28 ]. It has since been more explicitly proposed as a biofilm control method in more recent reviews [ 7 , 29 , 30 ].…”