Diamonds are a scientist’s best friend

Monday, June 30, 2014 - 07:08

Bonjour!  For the last few days, I have been working in the lab of Isabelle Daniel in beautiful Lyon, France.  I am here not just for the wine and history, but to do some really exciting science as well.  In the past, it has been shown that some organisms, such as the yeast Saccharomyces cerevisiea, can remain active at pressures up to ten times greater than those in the deepest ocean.   And that finding raised the question: how does this compare to organisms that actually come from high-pressure environments?  How much pressure can they withstand before they stop metabolizing, and how does that compare to the pressures at which they readily grow?  So here I am, along with some cultures isolated from the deep ocean, to try to find an answer.

The experiments I’m doing here involve two highly specialized instruments.  First, I will be using diamond anvil cells (or DACs) to create the high pressures that we’re interested in.  Second, I will use a Raman spectroscope to make measurements of the chemistry inside the DACs, and how it changes over time.  I’ll detail the spectroscope in my next post; for now, let’s keep talking DACs. These tiny chambers have a set of two diamonds – a thick anvil and a thinner window – which can have huge pressures applied to them without breaking and are still optically clear so the contents can be observed.  They are most often used in applications of physics and chemistry, such as the formation of ice structures in water that is pressurized, but they are also perfect for observing pressure effects on microorganisms.  While their beauty may make diamonds a girl’s best friend, their toughness and clarity make them very useful tools in the lab. 

Learning to use a DAC isn’t trivial.  The size means that tiny forceps, needles and a microscope are necessary to set up and load them.  Proper cleaning and alignment are necessary to make sure they don’t break under stress.  Once you add the microbes, it gets more complicated, requiring temperature regulation and protection from oxygen as well.  So for the last several days, I have been training in the use and mechanics of the DACs, honing my skills to prepare for the experiments we have planned.  The photo shows tools of the trade.  On the left is the base of the DAC with the diamond window, and on the right is the lid with the anvil.  The forceps and needle are used to manipulate the tiny metal gasket, microscopic ruby beads, and droplet of microbial culture that all go into the DAC before it is closed and pressurized.

This week, I will begin working with the spectroscope, so stay tuned for another update!