The aim of this work was to evaluate the cytotoxicity of Arthrospira platensis Extracellular Polymeric Substances (EPS) for colon cancer and kidney cell lines. Results showed that EPS were free from cytotoxic effects. A variety of solvents were assessed for their ability to extract the bioactive ingredients from EPS. Methanol gave the highest yield (75.75%) than other solvents. The extracts were tested for activities against a collection of Gram+/- bacteria. The methanol extract exhibited a more potent activity than the other organic extracts, whereas the aqueous extract was active against Staphylococcus epidermis (Gram+) and Salmonella typhimurium (Gram-). Finally, The extracts were also tested for the antioxidant activity, using the Trolox Equivalent Antioxidant Activity assay. The methanol extract displayed a moderate antioxidant activity (TEAC = 0.027 mg/ml). The HPLC analysis of this extract revealed two distinct peaks: 8.1 kDa (8.31 min) and 4.1 kDa (8.54 min)

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Combined effect of light intensity and glucose concentration on Arthrospira platensis growth and photosynthetic response was evaluated using a 3 2 factorial design. This design was carried out with light levels of 50, 100, and 150 µmol photons m −2 s −1 and glucose concentrations of 0.5, 1.5, and 2.5 gL −1 . Results from the response surface methodology were that the highest level of light intensity and glucose concentration improved biomass (1.33 gL −1 ), maximum specific growth rate (0.49 day −1 ), and net photosynthetic rate (139.89 µmol O 2 mg Chl −1 h −1 ). Furthermore, the interaction of both factors showed that at low light, glucose had a low effect on maximum biomass and maximal net photosynthetic rate. However, at the highest light levels, the effect of glucose was more sensitive and the increase of glucose concentration increased the levels of all responses. The rates of the instantaneous relative growth, net photosynthesis, and dark respiration of growth cultures showed two different phases in mixotrophic condition. The first was distinguished by the preponderance of the photoautotrophic mode; the second was based mainly on photoheterotrophy.

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In Tunisia, Monastir bay, extending for 38 km along the eastern coast of Tunisia, harbors different species of bivalves such as the clam Ruditapes decussatus, a species of major socio-economic interest. Despite its importance, no studies have been carried out about the morphology of this mollusc in Monastir bay. Thus, the current study aimed to analyze the shell morphological variations in the European clam Ruditapes decussatus from Monastir Bay coast. The comparison of the shell shape of individuals from HIGHLIGHTS• Ruditapes decussatus from four sites belonging to Monastir bay (Tunisia) was first time analyzed based on morphometry and comparative statistics.• The site of Ksiba was distinguishable from other sites by larger and heavier specimens.• The sub-trapezoidal shape was dominant with small-size classes, in most sites.• The principal component analysis (PCA) revealed different population groups, with two intrapopulation groups for Sokrine site.• Allometric relationships showed highly significant correlation with different growth patterns (positive allometric, negative allometric and isometric).

The macrolitter monitoring was investigated on 3 beaches on Monastir coastal (Palmier, Marina, Karaia) and on Kuriat Island during 4 seasons. The highest abundance and density of macrolitter were recorded on the beaches of Marina (13540 items/100m; 8.49 items m-2) and Karaia (6842 items/100m; 6.11 items m-2) during spring. According to Clean Coast Index, these 2 beaches were classified as extremely dirty whereas Kuriat Island was considered as very clean. Plastic items corresponded to the highest concentration of litter in studied sites and varying between 69% and 89% of total items. Cigarette butts are the most frequent type of debris

In the framework of COMMON MED-project, a sampling campaign was carried out during December 2020 along two radials namely: T1 and T2. The findings showed that microplastic particles (MPs), ranging from 0.31 to 4.9 mm. For all samples, white color and fragments are the most common. As well, HDPE and PE are the predominant polymers. The concentrations of MPs varied between 62,095,032 and 260,979,12 items/km² with a density of 4 times greater in the T2 radial, which shows the influence of urban and marina origin on plastic contamination among seaside tourist one.