Biochemical Composition of Marine Microalgae and Their Potential Antimicrobial Activity

This study is to investigate biochemical compositions of two species of marine microalgae, Chlorella ellipsoidea of Chlorophyta and Tetraselmis suecica of Prasinophyta, and to assess their potential antimicrobial activities. Crude protein, lipid and carbohydrate for C. ellipsoidea were 43.15%, 12.63% and 13.09%, respectively, and those for T. suecica were 44.95%, 4.80% and 24.05 %, respectively. The major amino acids of the two microalgae were aspartic acid, glutamic acid, glycine, alanine, valine, leucine, lysine and proline, and no significant difference between the amino acid compositions of both microalgae was observed. The major sugars for both microalgae were glucose, galactose and mannose, and glucose contents showed the highest level, 58.70% for C. ellipsoidea and 57.86 % for T. suecica. The major mineral contents of both microalgae for 100 g were Ca (3,114 ㎎ in C. ellipoidea and 3,389 ㎎ in T. suecica) and followed by Na (2,881 ㎎), K (548 ㎎) and Mg (545 ㎎) for C. ellipsoidea and Na (1,832 ㎎), Mg (1,510 ㎎) and K (548 ㎎) for T. suecica. In the content of ATP-related compound, hypoxanthine in C. ellipsoidea and IMP in T. succica were absolutely dominant compounds. The highest content of fatty acid in C. ellipsoidea was 20:4, 27.15% and that in T. suecica was 18:3 (ω-6), 18.10%. In case of physiologically important polyunsaturated fatty acids like eicosapentaenoic acid (20:5) and docosahexaenoic acid (22:6), both microalgae possessed just trace amounts but was rich in arachidonic acid (20:4). Vitamin content in both microalgae was significantly high in choline and inositol. In antimicrobial activity by water- and fat-soluble fraction of the micro algae, hexane extract in the fat-soluble fraction of C. elliposidea inhibited the growth of Bacillus subtilis by 96% bactericidal activity and tetrachlorocarbon extract of T. suecica indicated relatively excellent antimicrobial activity (81 % bactericidal activity) against Escherichia coli. Hot water extract among water-soluble fraction of both micro algae almost suppressed the growth of Staphylococcus aureus by 96 % bactericidal activity.