BIOACTIVE SECONDARY METABOLITES PRODUCED BY MARINE MICROORGANISMS: THEIR ISOLATION, STRUCTURAL ELUCIDATION AND FUNCTION

摘要

Compared to their terrestrial counterparts, marine microorganisms seem to be a relatively unexplored resource for novel bioactive metabolites. This thesis research aimed to discover new bioactive compounds of pharmaceutical value from the secondary metabolites produced by marine bacteria and fungi. The ecological role of marine bacteria involving the production of antibacterial metabolites was also investigated.This thesis describes three different studies, all of which are focused on the secondary metabolites produced by marine bacteria or fungi. First, bacteria-bacteria antagonism as a mechanism limiting the spread of Vibrio cholerae in the ocean was investigated using a marine particle-attached bacterial model, SWAT3, for its ability to prevent the colonization of particles and hence the growth of V. cholerae, by producing a antibacterial agent, andrimid. Second, the biosynthesis of CNC352.223, a novel metabolite derived from a marine fungus was explored using stable isotopic feeding experiments. Third, a marine-derived Halobacillus sp. culture C42, was investigated for its production of bacterial cell-cell signaling-antagonists since compounds possessing this type of activity may lead to a new generation of antibiotics. Two bioactive metabolites were isolated from C42 culture. Their bioactivity against bacterial cell-cell communication system was also examined.