Biotransformations of paralytic shellfish toxins by bacteria isolated frombivalve molluscs

Due to the possibility that bacteria could be involved in the clearance of paralytic shellfish toxins (PST) from bivalve molluscs, investigations into which, if any, bacteria were able to grow at the expense of PST focused on several common shellfish species. These species were blue mussels, oysters , razor fish, cockles, and queen and king scallops, Bacteria associated wit h these shellfish were isolated on marine agar 2216 and characterized by th eir carbon utilization profiles (BIOLOG), Selected isolates from groups dem onstrating 90% similarity were screened for their ability to metabolize a r ange of PST (gonyautoxins 1 and 4 [GTX 1/4], GTX 2/3, GTX 5, saxitoxin, and neosaxitoxin) using a novel screening method and confirming its results by high-performance liquid chromatography. Results suggest that molluscan bac teria have different capacities to utilize and transform PST analogues, For example, isolates M12 and R65 were able to reductively transform GTX 1/4 w ith concomitant production of GTX 2/3, while isolate Q5 apparently degraded GTX 1/4 without the appearance of other GTXs, Other observed possible mech anisms of PST transformations include decarbamoylation by isolate M12 and s ulfation of GTXs by isolates Q5, R65, M12, and C3, These findings raise que stions as to the possible role of bacteria resident in the shellfish food t ransport system. Some researchers have suggested that the microflora play a role in supplying nutritional requirements of the host, This study demonst rates that bacteria may also be involved in PST transformation and eliminat ion in molluscan species.