Biotransformation of arsenobetaine to trimethylarsine oxide by marine microorganisms in a gill of clam Meretrix Lusoria

The tetramethylarsonium ion has been found in the gill of the clam Meretrix lusoria. We attempted to confirm the conversion of arsenobetaine to the tetramethylarsonium ion in a culture with marine microorganisms occurring in the gill of the clam Meretrix lusoria. Arsenobetaine was aerobically incubated with microorganisms. A garlic-like odor was faintly detected after 5 to 8 days incubation. The mass spectrum of the odorous substance was essentially identical with that of synthetic trimethylarsine. Trimethylarsine oxide (TMAO) was also detected in the culture medium after 3 weeks incubation. Arsenobetaine was biotransformed to TMAO during the incubation in the culture growth by the marine microorganisms. Tetramethylarsonium ion was not detected in the culture medium even after 72 days incubation.