ABSTRACT
Duplicate plates methods and two purposive extraction methods (extracting phenols with 80% ethanol for 3 times after extracting lipids with other for 13 hours in soxhlot extractor)were used to research antimicrobial ability of nine common seaweeds in Qingdao coast. All extracts of nine seaweeds showed considerable activity against Bacillus subtilis, however,only three extracts,belonging to three species respectively,were effective against Escherichia coli. Several seaweeds not showing antimicrobial activity in previous tests showed considerabal effects. Gas chromatography was applied to analyse the contents of fatty acids in six kinds of lipids. C12-C22 saturated and unsaturated fatty acids were detected but no positive relation between the contents of unsaturated fatty acids and inhibition abilities were found.