Comparative effects of indole derivatives as antifouling agents on the growth of two marine diatom species

Abstract

Antifouling agents, used to prevent biofouling, need to be assessed for their impacts on marine organisms and environment before the application. Diatoms are one of the main components of fouling biofilms, which play important roles in the formation of biofouling. Particularly, diatoms are also the important ingredients of primary production and present interest as ecotoxicological models in marine environment. In this study, two benthic diatoms Nitzschia closterium f. minutissima and Navicula climacospheniae, widely distributed in fouling biofilm, were used as models for screening the activities of potential antifoulants. Nine indole derivatives were tested and CuSO 4 was used as a reference. Indole derivatives showed significant anti-algal activities and the EC 50 values of most indole derivatives were lower than that of CuSO 4 . Halogen substituent enhanced the anti-algal activities of compounds, and the most efficient compounds for N. closterium f. minutissima were gramine and 7-chloroindole with the EC 50 values of 1.94 and 2.1 mg/L, while for N. climacospheniae, 7-chloroindole and 6-bromoindole were the most efficient and the EC 50 values were 3.91 and 4.25 mg/L, respectively. In conclusion, indole derivatives would be one of the promising candidates as antifoulants and our results strengthened the need to perform antifouling activity assays and environment-friendly evaluations.

The influence of bacterial quorum-sensing inhibitors against the formation of the diatom-biofilm

“…In this study, QSIs showed dose-dependent effects on the growth of diatoms and the effects were closely related to diatom species which were similar to our previous report that anti-algal activities of indole derivatives were dependent on the diatom species. [30] From the results of specific growth rates, the inhibitory activity of 4-nitropyridine-N-oxide against Cylindrotheca sp. was superior to 3,4-dibromo-2(5)H-furanone and indole.…”

Review on Molecular Mechanisms of Antifouling Compounds: An Update since 2012

“…Antifouling compounds also interfere with the homeostasis of cellular calcium ions (Ca 2+ ) to inhibit the attachment of fouling organisms. For example, halogenated indole derivatives (i.e., gramine, 6-chloroindole, 7-chloroindole and 6-bromoindole) can trigger the efflux of Ca 2+ from the intracellular environment and the resulting reduction in Ca 2+ abundance within cells probably contributes to the inhibition of settlement of fouling organisms (e.g., bacteria and algae) [ 10 , 11 ]. Polyphosphate, a type of orthophosphate polymer, can attach to the bacterial cell membrane and chelate the Ca 2+ there, resulting in cell death and inhibition of biofilm growth [ 12 ].…”

Bacillus pumilus Marinos Inhibidores de la Fijación de Microalgas a Sustratos Artificiales

“…Estas bioincrustaciones comprenden desde proteínas, polisacáridos y proteoglicanos (Maitrayee, 2012), seguido por la colonización de microorganismos como bacterias (Flemming y Wingender, 2010). Luego por diatomeas que son las principales microalgas colonizadoras de sustratos contaminados (Yang et al, 2015). Finalmente colonizan los sustratos macro organismos como invertebrados marinos, generando posteriormente una acumulación estable que provocan graves problemas (Jhaveri y Murthy, 2016).…”