Effect of essential oil- and iodine treatments on the bacterial microbiota of the brown alga Ectocarpus siliculosus

Abstract

Macroalgae live in tight association with bacterial communities, which impact most aspects of their biology. Clean, ideally axenic, algal starting material is required to control and study these interactions. Antibiotics are routinely used to generate clean tissue; however, bacterial resistance to antibiotics is increasingly widespread and sometimes related to the emergence of potentially pathogenic, multi-resistant strains.In this study, we explore the suitability of two alternative treatments for use with algal cultures: essential oils (EOs; thyme, oregano, and eucalyptus) and povidone-iodine.The impact of these treatments on bacterial communities was assessed by bacterial cell counts, inhibition diameter experiments, and 16S-metabarcoding. Our data show that thyme and oregano essential oils (50% solution in DMSO, 15h incubation) efficiently reduced the bacterial load of algae without introducing compositional biases, but they did not eliminate all bacteria. Povidone-iodine (2% and 5% solution in artificial seawater, 10min incubation) both reduced and changed the alga-associated bacterial community, similar to the antibiotic treatment. The proposed EO-and povidone-iodine protocols are thus promising alternatives when only a reduction of bacterial abundance is necessary and where the phenomena of antibiotic resistance are likely to arise. BBDIodine and essential oil effects on algal microbiome 2 / 28

Real-Time Measurements of Botanical Disinfectant Emissions, Transformations, and Multiphase Inhalation Exposures in Buildings

“…Many of these products incorporate thymol (C 10 H 14 O) as the active ingredient. Thymol has been shown to be effective as an antioxidant , and antimicrobial. − Thymol has been used in wound dressings, , in-feed antibiotics, and antibacterial products − as it can disrupt bacterial cell membrane integrity and initiate cell death . Thymol-based oral rinses have shown >99.9% efficacy in inactivating SARS-CoV-2 surrogates. , Thymol-based disinfectants are included in List N…”