ABSTRACT
Understanding and sensing microbial biofilm formation onto surfaces remains highly challenging for preventing corrosion and biofouling processes. For that purpose, we have thoroughly investigated biofilm formation onto glassy carbon electrode surfaces by using electrochemical technics. Pseudomonas aeruginosa was studied because of its remarkable ability to form biofilms in many environments. The modification of the electrode-solution interface during biofilm growth was monitored by in-situ measurement of the open-circuit potential and correlated with results obtained by electrochemical impedance spectroscopy, cyclic voltammetry, scanning electron microscopy and bioassays. The sensing of the biofilm formation hence suggests a multi-steps mechanism, which may include pre-formation of an insulating layer onto the surface prior to the bacteria adhesion and biofilm formation.
Subject(s)
Bacterial Adhesion , Biofouling , Pseudomonas aeruginosa , Biofilms , Biofouling/prevention & control , CarbonABSTRACT
This paper focuses on the activity spectrum of three dimethylalkyl tertiary amines as potential active molecules and the corresponding ammonium salt-based antifouling (AF) paints. Bioassays (using marine bacteria, microalgae and barnacles) and field tests were combined to assess the AF activity of coatings. Bioassay results demonstrated that the ammonium salt-based paints did not inhibit the growth of microorganisms (except the dimethyldodecylammonium-based coatings) and that the tertiary amines were potent towards bacteria, diatoms, and barnacle larvae at non-toxic concentrations (therapeutic ratio, LC50/EC50, <1). The results from field tests indicated that the ammonium salt-based coatings inhibited the settlement of macrofouling and the dimethylhexadecylammonium-based coatings provided protection against slime in comparison with PVC blank panels. Thus, results from laboratory assays did not fully concur with the AF activity of the paints in the field trial.
Subject(s)
Aquatic Organisms , Biofouling/prevention & control , Biological Assay , Copper/chemistry , Paint/analysis , Polymethacrylic Acids/chemistry , Quaternary Ammonium Compounds/chemistry , Adhesives/chemistry , Animals , Aquatic Organisms/drug effects , Aquatic Organisms/physiology , Bacteria/drug effects , Bacteria/growth & development , Bacteria/metabolism , Carboxylic Acids/chemistry , Clinical Laboratory Techniques , Diatoms/drug effects , Diatoms/physiology , Equipment Contamination/prevention & control , Immersion , Ion Exchange Resins/chemistry , Microalgae/drug effects , Microalgae/physiology , Quaternary Ammonium Compounds/toxicity , Thoracica/drug effects , Thoracica/physiologyABSTRACT
Although a total ban on the use of TBT coatings is not expected in the short term, there is a growing need for environmentally safe antifouling systems. A search for new non-toxic antifoulants has been carried out among marine macroalgae. Antifouling activity of aqueous, ethanolic and dichloromethane extracts from 30 marine algae from Brittany coast (France) was examined in vitro against 35 isolates of marine bacteria. About 20% of the extracts were found to be active. The high levels of inhibitory activities against bacteria recorded in some extracts and the absence of toxicity on the development of oyster and sea urchin larvae and to mouse fibroblast growth suggests a potential for novel active ingredients in antifouling preparations.
Subject(s)
Anti-Bacterial Agents/pharmacology , Bacteria/drug effects , Biofilms/drug effects , Eukaryota/metabolism , Paint/toxicity , Animals , Bacteria/growth & development , Larva , Marine Biology , Ostreidae/drug effects , Ostreidae/growth & development , Sea Urchins/drug effects , Sea Urchins/growth & development , Water MicrobiologyABSTRACT
The inhibitory effects of aqueous, ethanolic and dichloromethane fractions from 16 marine algae from the Atlantic shores of North-East Brittany, France, have been investigated against microorganisms frequently associated with immersed surfaces. The extracts were tested in vitro against isolates of marine fungi, bacteria and yeasts potentially involved at different stages in the formation of biofilms in the sea. The high levels of inhibitory activity of nine extracts against marine fungi and Gram-positive bacteria and their apparent absence of toxicity against larvae of oysters and sea urchins suggests a potential for novel active ingredients.
