Polyphenol profiles were characterized in extracts of three Chilean brown seaweeds, Durvillaea antarctica (Chamisso) Hariot, Lessonia spicata (Suhr) Santelices, and Macrocystis integrifolia (Bory) by liquid chromatography with mass spectrometry detection (LC-MS/MS). Phlorotannins with different degrees of polymerization were identified in D. antarctica (trimers to octamers) and L. spicata (trimers to tetramers). No signals related to phlorotannins compounds were detected in M. integrifolia. L. spicata and M. integrifolia showed a great variety of flavonoid compounds in comparison with D. antarctica, mainly identified as glycoside forms in all the extracts. The antioxidant activity of brown seaweed extracts measured by ferric reducing power (FRAP) and oxygen radical absorbance capacity (ORAC) was significantly higher in D. antarctica, followed by M. integrifolia and L. spicata, in line with the total phenolic (TP) content. However, D. antarctica and M. integrifolia showed similar activity for free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) in spite of the differences found in TP content. D. antarctica as well as L. spicata would represent a potential source of phlorotannins, whereas M. integrifolia could be considered as an alternative source of flavonoids. The identification of polyphenols in extracts of Chilean brown seaweeds opens innovative opportunities for their use in the food and pharmaceutical industries.

Aims: The primary goal of this study was to characterize the existence of a functional c‐di‐GMP pathway in the bioleaching bacterium Acidithiobacillus ferrooxidans. Methods and Results: A bioinformatic search revealed that the genome sequence of At. ferrooxidans ATCC 23270 codes for several proteins involved in the c‐di‐GMP pathway, including diguanylate cyclases (DGC), phosphodiesterases and PilZ effector proteins. Overexpression in Escherichia coli demonstrated that four At. ferrooxidans genes code for proteins containing GGDEF/EAL domains with functional DGC activity. MS/MS analysis allowed the identification of c‐di‐GMP in nucleotide preparations obtained from At. ferrooxidans cells. In addition, c‐di‐GMP levels in cells grown on the surface of solid energetic substrates such as sulfur prills or pyrite were higher than those measured in ferrous iron planktonic cells. Conclusions: At. ferrooxidans possesses a functional c‐di‐GMP pathway that could play a key role in At. ferrooxidans biofilm formation during bioleaching processes. Significance and Impact of the Study: This is the first global study about the c‐di‐GMP pathway in an acidophilic bacterium of great interest for the biomining industry. It opens a new way to explore the regulation of biofilm formation by biomining micro‐organisms during the bioleaching process.