Thursday, September 12, 2013

Magnetite Producers

Weather:
The clouds are back, but the air temperature is warm (mid- 60's); the seas are relatively calm.

Science Update:

Today's Objectives:

1) Day 3 of the 5 day "Pressure Dive" with ROV Jason (dive J2-730) to collect pressure data on a circuit of 10 Benchmarks (green dots on map at right) - in progress!

Magnetite Producers

One of the challenges of studying microbes and talking about your work with friends is that microorganisms (by their very nature) are really hard to see!

Dr. Jim Holden of University of Massachusetts at Amherst has a great way to share his research, or at least to show the activity of the microbes he's studying at Axial Seamount. Jim determines sites where he wants to collect vent fluids with the fluid sampler on ROV Jason (below left). The submersible's arm removes the sampler from its holster on the front payload basket (below center) and then the submersible's pilot works with Jim to get it positioned exactly where he wants to collect a sample. Fluid samples are collected in bottles on ROV Jason until it returns to the surface.


Sampling microbes at El Guapo Vent (left) in the International Hydrothermal Vent Field (see map above) with the fluid sampler (center). Fluids are collected from the vent and delivered through the metal hose on the left of the device into bags in bottles (right) on ROV Jason.
Once back on the surface, Jim extracts microbes from the vent fluid samples and completes several sets of experiments with the samples. One such experiment is to investigate the byproduct produced when the sample is in the presence of rust. To maintain consistency of all his experiments, Jim needs the "rust" component to be standardized so uses the mineral ferrihydrite (a hydrous ferric oxyhydroxide Fe3+4O6(H2O) see photo below left). He inoculates (squirts) an aliquot (a portion of the fluid sample) of the vent water sample with the microbes he's studying into ferrihydrite in solution and lets the reactions proceed. The results are shown in the image below right in which Jim is holding a magnet against the test tube to show that the microbes have changed the ferrihydrite to produce a byproduct, which Jim believes is the mineral magnetite (Fe3O4). We can't complete the mineral identification on the ship, but similar byproducts have been produced by this type of hyperthermophilic (an organism that likes to live at high temperature) microbe in previous work Jim has done in his lab at Amherst. These kinds of microbes grow optimally at very high temperatures (between 80-100° C).


Test tubes used to detect the presence of hyperthermophilic microbes in vent fluids collected from Anemone Vent of the ASHES Hydrothermal Vent Field at Axial Seamount. In both images, the test tube on the left contains the ferrihydrite solution. The test tube on the right in both images is the byproduct collected after inoculation. Note that in the image on the right, a magnet is used to show that the byproduct in the right side test tube is magnetic.
Test tubes with Jim's samples can demonstrate the presence of hyperthermophilic microbes in vent fluids collected from Anemone Vent of the ASHES Hydrothermal Vent Field at Axial Seamount. In both images, the test tube on the left contains the ferrrihydrite solution. The test tube on the right in both images is how it looked after inoculation and incubation. Note that in the image on the right, a magnet is used to show that the byproduct in the right side test tube is magnetic.


So not only has Jim been able to collect and at least partly characterize microbes at Axial Seamount, he also has an easy visualization to help demonstrate the activities of those organisms to those of us who can't actually see the microorganisms!


video