Antimicrobial Activity of Marine Microalgae Isolated From Moroccan Coastlines

Abstract

The present investigation aimed to study antimicrobial activities in marine microalgae, screened from Moroccan coastlines. Ethanolic extracts were prepared from the microalgae and evaluated each against the bacteria: Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus, the yeast Candida albicans and the fungus Aspergillus niger. The highest antibacterial activity was found in the extract of Tetraselmis sp. which exhibited an inhibitory effect against the three bacteria with a MIC of 2.6 to 3.0 mg extract per mL culture. Extracts from the other microalgae: Dunaliella Salina, Nannochloropsis gaditana, Dunaliella sp., Phaeodactylum tricornutum and Isochrisis sp. each showed inhibitory activity against E. coli or P. aeruginosa with a MIC of 2.6 to 4.3 mg extract per mL. The extract of N. gaditana also inhibited S. aureus growth. However, the extracts from the microalgae, Chaetoceros sp. and Chlorella sp. showed no effect under the applied experimental conditions. All the tested extracts inhibited the growth of C. albicans; the highest activity was obtained from N. gaditana with a MIC of 4.0 mg extract per mL culture. Aspergillus niger appeared to be resistant to the effect of the extracts. The observed antimicrobial activities were linked to the contents of the extracts in fatty acids, carotenoids and phenolic compounds. In conclusion, the studied microalgae could be considered as a potential natural source of bioactive compounds with antimicrobial activities.

High-Throughput Screening of Chlorella Vulgaris Growth Kinetics inside a Droplet-Based Microfluidic Device under Irradiance and Nitrate Stress Conditions

“…Microalgae are photosynthetic organisms and a promising feedstock for different products, such as antibiotics, cosmetics, toothpastes, alginates, agar [1,2,3], and renewable fuels, e.g., biodiesel, biohydrogen, and bioethanol [4,5], because they conserve water and land resources [6]. They can also be used as biofertilizers and bioremediators [7].…”

Phytochemical screening, metabolite profiling and enhanced antimicrobial activities of microalgal crude extracts in co-application with silver nanoparticle

“…The extracted functional groups may be polar hydrophilic or non-polar lipophilic which determine the outcome of the action on the cell membrane and other components of the G −ve and G +ve bacteria (Shannon and Abu-ghannam 2016), and eventually the penetration of the bioactive compounds into the bacterial cells. N. gaditana has shown inhibitory activities against P. aeruginosa, S. aureus and E. coli with an MIC of 2.6-4.3 mg/mL which can be correlated to the level of fatty acids, phenolics and carotenoids (Maadane et al 2017). Higher inhibition zone has been achieved with the methanolic extracts of Tetraselmis sp., as compared to diethyl ether and hexane, against E. coli (16 mm) and S. aureus (15 mm), but all extracts exhibit no activities against Proteus vulgaris.…”

Bioactive Properties of Marine Phenolics

“…They can even grow on industrial wastewaters [ 49 ]. The valuable bioactives with pharmaceutical, food, feed, and cosmetic applications [ 50 , 51 ] from microalgae could be relevant regarding the higher profitability of the cultivation processes and could complement the energetic application [ 47 ]. In fact, the extraction of phenolic compounds from microalgae biomass does not interfere with already established processes such as biofuel production [ 27 ].…”

“…Moreover, synthetic mixtures of phenolic acids from both microalgae were less efficient than the natural extracts (EC 50 values of 49.6 μg/mL and 33.9 μg/mL for Nannochloropsis and Spirulina phenolic acid extracts, respectively) to inhibit fungal growth, indicating that no purification is required [ 27 ]. Maadame et al [ 50 ] evaluated the antimicrobial activities of nine marine microalgae from Moroccan coastlines ( Nannochloropsis gaditana , Dunaliella salina , Dunaliella sp., Phaeodactylum tricornutum , Isochrysis sp., Navicula sp., Chaeotoceros sp., Chlorella sp. and Tetraselmis sp.).…”