Benefit of the nutritional and mineral composition of sea lettuce from a traditional salina: Implications for human consumption

The proximal composition and its seasonal variation of the green seaweed Ulva sp. harvested in a traditional saline (earthen ponds used for marine salt extraction) from Cadiz Bay (Southern Spain) was evaluated. Ulva sp. was also collected in a reference location within the Bay in order to compare and evaluate the effects of the particular characteristics of the saline in the composition of the macroalgae. Moisture, protein, lipid, ash, carbohydrate, fiber and macro- (Na, K, Ca, Mg), micro-mineral contents (Fe, Zn, Cu) and heavy metals (As, Cd, Co, Cr, Hg, Ni, Pb, Sn) of harvested biomass samples as well as environmental parameters of seawater (temperature, salinity, pH, DO, NH4+, NO3-, NO2- and PO43-) were measured. The results showed that Ulva sp. from the earthen ponds in the traditional salina was a better source of proteins, lipids, K and Mg, highlighting in summer with values of 27.54 % versus 6.11 %; 6.71 % versus 3.26 %; 26.60 mg g-1 versus 14.21 mg g-1 and 23.13 mg g-1 versus 17.79 mg g-1, respectively. It also had Na/K and Ca/Mg ratios of less than one, suggesting a healthy food source. Considering the Commission Recommendation (EU) 2018/464 as a working reference, Ulva sp. did not exceed the limit of toxic metals for human consumption.A season and site-season significant interaction on the composition of the seaweeds was observed. The proximal and mineral composition of Ulva sp. was influenced by the special features and environmental conditions of the earthen ponds. Hence, significant differences were observed in the macroalgae collected in the earthen ponds in summer and autumn, in contrast to the winter and spring samples, whose characteristics were similar to those from the inner bay. The closure of the lock-gates in summer to favor the production of salt significantly modified the environmental characteristics of the saline, affecting the physiological capacity of Ulva sp. to assimilate and storage nutrients, and therefore its tissue composition. As a consequence, the highest contents of lipid, ash, Ca, K, Mg and Fe were estimated in the macroalgae.

Dust-borne microbes affect Ulva ohnoi's growth and physiological state

The marine macroalgae Ulva sp. is considered an ecosystem engineer in rocky shores of temperate waters worldwide. Ulva sp. harbors a rich diversity of associated microbial epibionts, which are known to affect the algae's typical morphological development and 'health'. We examined the interaction between airborne microbes derived from atmospheric aerosols and Ulva ohnoi growth and physiological state. Specifically, we measured U. ohnoi growth rates and photosynthetic efficiency (Fv/Fm), alongside its microbial epibionts abundance, activity and diversity following dust (containing nutrients and airborne microorganisms) or UV-treated dust (only nutrients) amendments to filtered seawater. Parallel incubations with epibionts-free U. ohnoi (treated with antibiotics that removed the algae epibionts) were also tested to specifically examine if dust-borne microbes can replenish the epibiont community of U. ohnoi. We show that viable airborne microbes can restore U. ohnoi natural microbial epibionts communities, thereby keeping the seaweed alive and 'healthy'. These results suggest that microbes delivered through atmospheric aerosols can affect epiphyte biodiversity in marine flora, especially in areas subjected to high annual atmospheric dust deposition such as the Mediterranean Sea.

Two species of Ulva inhibits the progression of cervical cancer cells SiHa by means of autophagic cell death induction

Edible green algal seaweeds, namely Ulva intestinalis and Ulva lactuca constitute a significant repository of popular herbal medicines in the Traditional Chinese Medicinal system. The present study aimed to assess the anticancer potential of these algal members and its mode of action in cervical cancer cells SiHa. The algal samples primarily extracted in methanol was fractionated into hexane, chloroform, and aqueous algal fractions, which inhibited the proliferation of SiHa cells in a dose-dependent manner, with the algal chloroform fractions harbouring the lowest IC50 dose of 141.38 µg/ml in U. intestinalis and 445.278 µg/ml in U. lactuca. These algal chloroform fractions when studied for their in-depth mode of action, were found to damage and pulverise the nuclei, resulting in a concomitant increase in subG0-phase of SiHa cells, studied by flow cytometry. The algal treatment also caused an increase in the number of acidic vesicles and enhanced the expression of LC3BII, p62 and atg12 proteins, which together pointed out autophagy as the induced mode of cell death. Upregulated Bax and p53 expression along with decreased Bcl2 expression also correlated to autophagic cell death. Decreased expression of E6 viral oncogene was noted as a significant response to algal fractions. Lastly, these potent algal fractions when characterised pharmacologically through GC-MS analysis were found to be rich in unsaturated fatty acids, majorly palmitic acid. Hence, this study concludes that the two species of Ulva successfully decreased the proliferation of SiHa cervical cancer cells through autophagy, hinting at palmitic acid being the major responsible bioactive compound in both.