Community structure of MTB was investigated by
optical microscopy after magnetic collection. MTB were
found to be present at 105–106 per mL. As reported in
other studies, the collected MTB displayed cocci as the
major cell morphology (Suppl data 3). Multicellular
magnetotactic prokaryotes (MMPs) displayed a pineapple-
like form, with a diameter of 7.9 ± 0.6 lm, as
revealed by light microscopy analysis. Their density was
estimated to 10–100 per mL. Their morphology was
similar to that from the Yellow Sea [30]. Several other
forms of MTB were observed in minority, such as vibrios,
spirilla, rods, and mulberry-like multicellular forms
(diameter of 5.1 ± 0.6 lm).