Presentation Information
[P01-134]Visible-Light-Induced Antibiofilm Activity of Tetrakis(pentafluorophenyl)porphyrin-Dispersed Alkoxysilane Coatings
○Akiko Ogawa1, Hana Watanabe1, Shiho Hirohara2 (1. National Institute of Technology (KOSEN), Suzuka College (Japan), 2. National Institute of Technology (KOSEN), Okinawa College (Japan))
Keywords:
antibiofilm,tetrakis(pentafluorophenyl)porphyrin,coating
[Purpose]
Biofilms consist of attached bacteria and their extracellular polymeric substances (EPS), and they readily form on various material surfaces including metals, tiles, and plastics. In marine environments, several bacteria form biofilms, and some genera, such as Vibrio and Pseudomonas, have been reported as tetrodotoxin (TTX) producers. Takifugu rubripes, a puffer fish species widely cultured for food, contains high amounts of TTX in the ovary and liver. This toxin is acquired through the food chain: marine biofilms represent the lowest trophic level, followed by shellfish, crustaceans, and echinoderms, with puffer fish at the highest level. Therefore, controlling biofilm formation is important during the aquaculture of T. rubripes in marine cages to avoid TTX accumulation.
In this study, we evaluated nine tetrakis(pentafluorophenyl)porphyrin (TFPP) derivatives for their antibiofilm properties. The TFPP compounds were dispersed in an alkoxysilane resin to prolong their surface activity and enhance durability in aqueous environments. The coated films were prepared on substrate specimens and used for biofilm formation tests.
[Method]
Biofilm formation tests were conducted using two bacterial species, Staphylococcus epidermidis and Halomonas aquamarina. S. epidermidis is commonly used as a standard bacterium for evaluating antibiofilm performance according to ISO guidelines, while H. aquamarina is a marine bacterium isolated from seawater and frequently used as a model organism for marine biofilm formation. Each specimen coated with TFPP-dispersed alkoxysilane resin was immersed in bacterial culture medium and incubated under constant LED illumination to activate the porphyrin-based compounds. After incubation, all specimens were submerged in 0.1% crystal violet solution to stain the formed biofilms and subsequently rinsed with purified water to remove excess dye. The stained biofilm regions were wiped using a 3 cm × 3 cm water-soluble nonwoven fabric. The fabric was then dissolved in 5 mL of 1.0% sodium dodecyl sulfate solution to extract the crystal violet. The absorbance of each solution was measured at 590 nm to quantify the amount of biofilm.
The antibiofilm activity, R (%), was calculated using the following equation: R (%) = (1 − W_treated / W_untreated) × 100, where W_treated is the absorbance of the TFPP-coated specimen and W_untreated is that of the alkoxysilane-coated specimen.
[Results and Consideration]
Using S. epidermidis, the average R values for all TFPP-coated specimens were positive, indicating that the coatings exhibited antibiofilm activity against S. epidermidis. In contrast, experiments using H. aquamarina produced inconsistent results. In the first experiment, the R values were negative for eight of the nine TFPP-coated specimens, suggesting enhanced biofilm formation. However, in the second experiment, positive R values were obtained for the same coatings, indicating antibiofilm activity. These contradictory results suggest that additional experiments under controlled marine-like conditions are necessary to clarify the antibiofilm properties of TFPP-dispersed alkoxysilane coatings and their potential applicability for preventing biofilm formation in marine environments.
Biofilms consist of attached bacteria and their extracellular polymeric substances (EPS), and they readily form on various material surfaces including metals, tiles, and plastics. In marine environments, several bacteria form biofilms, and some genera, such as Vibrio and Pseudomonas, have been reported as tetrodotoxin (TTX) producers. Takifugu rubripes, a puffer fish species widely cultured for food, contains high amounts of TTX in the ovary and liver. This toxin is acquired through the food chain: marine biofilms represent the lowest trophic level, followed by shellfish, crustaceans, and echinoderms, with puffer fish at the highest level. Therefore, controlling biofilm formation is important during the aquaculture of T. rubripes in marine cages to avoid TTX accumulation.
In this study, we evaluated nine tetrakis(pentafluorophenyl)porphyrin (TFPP) derivatives for their antibiofilm properties. The TFPP compounds were dispersed in an alkoxysilane resin to prolong their surface activity and enhance durability in aqueous environments. The coated films were prepared on substrate specimens and used for biofilm formation tests.
[Method]
Biofilm formation tests were conducted using two bacterial species, Staphylococcus epidermidis and Halomonas aquamarina. S. epidermidis is commonly used as a standard bacterium for evaluating antibiofilm performance according to ISO guidelines, while H. aquamarina is a marine bacterium isolated from seawater and frequently used as a model organism for marine biofilm formation. Each specimen coated with TFPP-dispersed alkoxysilane resin was immersed in bacterial culture medium and incubated under constant LED illumination to activate the porphyrin-based compounds. After incubation, all specimens were submerged in 0.1% crystal violet solution to stain the formed biofilms and subsequently rinsed with purified water to remove excess dye. The stained biofilm regions were wiped using a 3 cm × 3 cm water-soluble nonwoven fabric. The fabric was then dissolved in 5 mL of 1.0% sodium dodecyl sulfate solution to extract the crystal violet. The absorbance of each solution was measured at 590 nm to quantify the amount of biofilm.
The antibiofilm activity, R (%), was calculated using the following equation: R (%) = (1 − W_treated / W_untreated) × 100, where W_treated is the absorbance of the TFPP-coated specimen and W_untreated is that of the alkoxysilane-coated specimen.
[Results and Consideration]
Using S. epidermidis, the average R values for all TFPP-coated specimens were positive, indicating that the coatings exhibited antibiofilm activity against S. epidermidis. In contrast, experiments using H. aquamarina produced inconsistent results. In the first experiment, the R values were negative for eight of the nine TFPP-coated specimens, suggesting enhanced biofilm formation. However, in the second experiment, positive R values were obtained for the same coatings, indicating antibiofilm activity. These contradictory results suggest that additional experiments under controlled marine-like conditions are necessary to clarify the antibiofilm properties of TFPP-dispersed alkoxysilane coatings and their potential applicability for preventing biofilm formation in marine environments.
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