Microbiota of the Therapeutic Euganean Thermal Muds with a Focus on the Main Cyanobacteria Species

Abstract

The Euganean Thermal District has been known since Roman times for the therapeutic properties of peloids, obtained from natural clays that have undergone a traditional maturation process. This leads to the growth of a green microbial biofilm with Cyanobacteria and the target species Phormidium sp. ETS-05 as fundamental components for their ability to synthetize anti-inflammatory molecules. Currently, in-depth studies on the microbiota colonizing Euganean peloids, as in general on peloids utilized worldwide, are missing. This is the first characterization of the microbial community of Euganean thermal muds, also investigating the effects of environmental factors on its composition. We analysed 53 muds from 29 sites (Spas) using a polyphasic approach, finding a stable microbiota peculiar to the area. Differences among mud samples mainly depended on two parameters: water temperature and shading of mud maturation plants. In the range 37–47 °C and in the case of irradiance attenuation due to the presence of protective roofs, a statistically significant higher mud Chl a content was detected. Moreover, in these conditions, a characteristic microbial and Cyanobacteria population composition dominated by Phormidium sp. ETS-05 was observed. We also obtained the complete genome sequence of this target species using a mixed sequencing approach based on Illumina and Nanopore sequencing.

Microalgal Peloids for Cosmetic and Wellness Uses

“…Subsequent research by Gris et al (2020) on the same muds (Euganean Thermal Muds) confirmed that the predominant species is Phormidium sp. and that diversity is greater when the temperature is 37-47 • C. At lower and higher temperatures, populations lose stability, thus exhibiting a significant change in species composition, low biodiversity, and low cyanobacterial abundance [42]. Zampieri et al (2020) likewise noted the antiinflammatory activity of exopolyssacharides from Phormidium sp present in the Abano muds [43].…”

Metabolomic Characterization of a cf. Neolyngbya Cyanobacterium from the South China Sea Reveals Wenchangamide A, a Lipopeptide with In Vitro Apoptotic Potential in Colon Cancer Cells

“…There is great difficulty in growing axenic cultures of cyanobacteria; therefore, it is important to refer to the collected consortia as a whole. While several studies demonstrated that the microbiome of cyanobacteria is relatively stable between environmental samples and non-axenic cultures (mainly Proteobacteria and Bacteroidetes) [37], little is known about the microbiome associated with Lyngbya-like and Phormidium-like organisms [38]. An LC-MS/MS untargeted metabolomic approach [28] was utilized to overview the chemical potential of the prioritized South China Sea cf.…”

Taxonomy and Species Delimitation in Cyanobacteria

“…A clade of cyanobacteria owns also chlorophyll b, as green algae do, but without a direct phylogenetic relationship with these last organisms [3]. Cyanobacteria share the same environment of eukaryotic algae [4], even if the first have normally higher temperature optimum [5] and high capability of resistance to desiccation and water stress [6]. Moreover, cyanobacteria are widely distributed and can live in some extreme habitats on earth [7] and are one of the most diversified clades of bacteria [8].…”