## 4 Discussion  
The bio-prospecting of microalgae from local biotopes has been considered an efficient alternative to identify species of different genera that exhibit a wide of biotechnological activities [40; 41]. In this context, two microalgae strains, MA\({}_{\text{a1}}\) and MA\({}_{\text{n1}}\), were isolated from local marine habitat and identified as microalgae belonging to _Chlamydomonas_ and _Navicula_ genera of _Chlamydomonas_ and _Naviculaaceae_ families using the nuclear 18S rDNA gene as a universal DNA barcode marker [42]. Microalgae biomasses were characterized and a genus-dependent biochemical composition was observed, as previously  
Figure 4: Cytotoxic activities of _Chlamydomonas_ sp. MA\({}_{\text{a1}}\) and _Navicula_ sp. MA\({}_{\text{n1}}\) methanol extracts against SAF-1 and PLHC-1 cell lines. Data show means \(\pm\) SD (\(n\) = 5). Statistical significance was determined by one-way ANOVA followed by Duncan multiple range test; significant difference (\(p\) < 0.05) is indicated by different lowercase letters. Figure 5: Capacities of _Chlamydomonas_ sp. MA\({}_{\text{a1}}\) and _Navicula_ sp. MA\({}_{\text{n1}}\) to remove cadmium from aqueous solutions. Data show means \(\pm\) SD (\(n\) = 3). Statistical significance was determined by one-way ANOVA followed by Duncan multiple range test; no significant difference (\(p\) < 0.05) is indicated by the same lowercase letters. reported [43]. The obtained composition of the green microalgae isolate _Chlamydomonas_ sp. MA\({}_{\text{a1}}\) was in agreement with that reported by [PERSON] et al. [44], with a remarkable abundance of proteins of about 47.22%, while _Navicula_ sp. MA\({}_{\text{n1}}\) strain biomass was richer in organic compounds especially carbohydrates (50.83%) than previously studied _Navicula_ isolates [45; 46]. The growth pattern and biochemical composition of microalgae cells are closely related to biotic and abiotic culture parameters such as cultivation conditions and nutrient media composition and concentrations [44]. Both newly isolated strains exhibited moderate lipid contents. However, they were found to exhibit important proportions of mono-unsaturated and polyunsaturated fatty acids; 69.65% and 82.02% for _Chlamydomonas_ sp. MA\({}_{\text{a1}}\) and _Navicula_ sp. MA\({}_{\text{n1}}\), respectively. Fatty acid profiles have been considered as chemotaxonomical characteristics, since a comparatively higher homology of fatty acid profiles is always found within the strains with closer phylogenic relationships [47]. _Chlamydomonas_ sp. MA\({}_{\text{a1}}\) strain is particularly rich in monounsaturated especially oleic acid (C18:1n-9), vaccine acid (C18:1n-7), and polyunsaturated \(\alpha\)-linolenic acid (C18:3n-3) accounting for approximately 12.5%, 10.5%, and 30.08% of the total _Chlamydomonas_ sp. MA\({}_{\text{a1}}\) oil, respectively. The main abundant fatty acid in _Navicula_ sp. MA\({}_{\text{n1}}\) isolate is palmitoleic acid (C16:1n-7) representing 43.48% of the total fatty acids. The obtained results agree with multiple previously-published reports showing that almost all diatoms contained high proportions of (C16: 0) and (C16: 1n-7) fatty acids [48]. Unsaturated fatty acid production should be of great importance in different fields such as special human or animal dietary, nutraceuticalals, and/or cosmeceuticals given the functional properties of PUFAs and their health benefits [44]. In fact, PUFAs, especially n-3 PUFAs, have many potential applications including disease prevention and treatment [49]. Under oxidizing conditions, microalgae cells produce various antioxidants [50]. There are several reports on the evaluation of the antioxidant activity of many genera belonging to Cyanobacteria [51; 52], Chlorophyceae [53; 54; 55] and some diatoms [56]. The antioxidant and antibacterial properties investigation of newly isolated strains showed high potential of in vitro activities.