GC/MS identification and applications of bioactive seaweed extracts from Mediterranean coast of Egypt

Document Type : Original Article

Authors

1 Marine Microbiology Lab, Division of Marine Environment, National Institute of Oceanography and Fisheries, Egypt

2 Marine Pollution Lab, Division of Marine Environment, National Institute of Oceanography and Fisheries, Egypt

Abstract

The antibacterial activity of different seaweed species against five fish
pathogens (A. hydrophila, V. parahaemolyticus, V. alginolyticus, V. damsela and
Vibrio sp.) has been evaluated. The ethanolic extract of C. sinuosa (CSE1) and
dichloromethane extract of C. officinalis (COM) exhibited the highest antibacterial
activity with activity index (AI) = 1.4 ±0.74 and 1.2 ±0.71, respectively. When the
extracts were encapsulated into calcium alginate beads their antibacterial activity
against the most susceptible bacterial pathogens showed that the significant growth
inhibition was against V. parahaemolyticus after 5 min post addition of the beads
recording 1.4 and 2 fold decrease in the growth, respectively. Recycling of the
(CA/COM) beads was carried out for 7 successive cycles with success in
elimination of V. parahaemolyticus. The potential applications of encapsulated
extracts for elimination of microbial load in fish rearing water and antifouling
activity were proved in the current investigation. The chemical composition of the
bioactive extracts (CSE1) and (COM) was determined using GC/MS analysis
which revealed the presence of several constituents that have been reported to
exhibit antimicrobial activity. Additionally, the dichloromethane extract (COM)
produced six major components including n-nonadecane, 1,2,3-
propanetricarboxylic acid, 2-(acetyloxy)-, tributyl ester, 2-methylhexadecan-1-ol,
1-docosene, 1-eicosanol and chloroacetic acid, octadecyl ester. However, the
ethanolic extract (CSE1) was characterized by the presence of fatty acids, fatty
acids ethyl esters and aromatic hydrocarbon where the most abundant compound
was n-tridecanoic acid ethyl ester.

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