B3: Bathymodiolus, bacteria, and biomineralization by Eniko Kadar*

Bathymodiolus azoricus mussels

Like many bivalves, the deep-sea hydrothermal mussel Bathymodiolus azoricus anchors itself to the bottom using byssal threads. Bacteria have been spotted within these threads and may be responsible for the unusually high metal concentrations of iron, copper, and zinc in the byssus, as demonstrated by X-ray microanalysis of the deposits surrounding bacterial cells. Fluorescent probes, specific to the methanotroph endosymbiont bacteria typically found in the gills of these mussels, also hybridized with the intra-byssal bacteria. This suggests these symbiotic bacteria, in addition to providing the host with nutrients, may be playing a role in metal sequestration and deposition. It is interesting to speculate on their role in synthesis of organic molecules that may contribute to the adhesive properties of the byssal plaque in spite of corrosive conditions typical of hydrothermal vent environments. More broadly, the unprecedented metal levels in byssus, plus its frequent renewal rate due to the dynamic nature of the habitat, suggest that intra-byssal bacteria may have a great influence on biomineralisation/deposition of manganese, which in turn acts as a scavenger for other metals.

*IMAR Centre of the University of Azores, Horta, Portugal

More on this research can be found here and here
Electron dense deposition in a more advanced phase of biomineralisation within the collagenous net of the byssus with remains of bacterial cells at the origin of each deposition, credit Eniko Kadar
Higher magnification of one dead bacteria showing electron-dense deposition (darker areas) surrounding the cell, credit Eniko Kadar
Fluorescent in situ hybridization (FISH) showing intra-byssal bacteria ‘lighting up’ with the probe specific for the methanotroph gill symbionts, credit Eniko Kadar

Dr. M (1729 Posts)

Craig McClain is the Assistant Director of Science for the National Evolutionary Synthesis Center, a National Science Foundation supported initiative. He has conducted deep-sea research for 20 years and published over 50 papers in the area. He has participated in and led dozens of oceanographic expeditions taken him to the Antarctic and the most remote regions of the Pacific and Atlantic. Craig’s research focuses on how energy drives the biology of marine invertebrates from individuals to ecosystems, specifically, seeking to uncover how organisms are adapted to different levels of carbon availability, i.e. food, and how this determines the kinds and number of species in different parts of the oceans. Craig’s research has been featured on National Public Radio, Discovery Channel, Fox News, National Geographic and ABC News. In addition to his scientific research, Craig also advocates the need for scientists to connect with the public and is the founder and chief editor of the acclaimed Deep-Sea News (http://deepseanews.com/), a popular ocean-themed blog that has won numerous awards. His writing has been featured in Cosmos, Science Illustrated, American Scientist, Wired, Mental Floss, and the Open Lab: The Best Science Writing on the Web. His forthcoming book, Science of the South (http://www.scienceofthesouth.com/), connects cultural icons of South such as pecan pie with the science behind them.