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A novel method was developed for the screening and detection of fucoidanase activity in bacterial colonies using fucoidan–agarose plates and staining with hexadecyltrimethylammonium bromide (Cetavlon). Colonies with fucoidanase activity were indicated by a transparent halo. The medium containing undegraded fucoidan showed as a milk-colored background, but areas with degraded fucoidan under the colonies were visualized as a transparent halo.

As a result of the first study on secondary metabolites from the cosmopolitan bioluminescent marine tube polychaete Chaetopterus variopedatus, a new bicyclic guanidine alkaloid, 6-epi-monanchorin (1), along with the previously known monanchorin (2) were isolated. The structure of 1was elucidated by spectroscopic and chemical methods, including a cleavage of the C1–O7bond to obtain a secondary alcohol (3), which was used to determine the absolute configurations by Mosher's method. It was found that 1and 2were mainly accumulated in a secreted mucus special organ of the worm (food net), where green and blue-green microalgae were detected. A biosynthetic pathway to 6-epi-monanchorin and monanchorin from dietary polyenic fatty acid precursors was proposed.