Our Winograsky columns have come a long way from our previous post two weeks ago. To review what a Winogradsky column is and our goals for them please see: Adventures with Winogradskies.

After 4 weeks:

Green layers have started to develop on the top of some of the tubes and to a less visible extent on some of the larger containers.

In some tubes we are starting to see defined layers. Layers seem to vary between tubes containing seawater from different sample locations as well as between tubes with water from the same location.

Unfortunately, our tiny microcentrifuge tubes haven’t changed much in the past two weeks.

4 Weeks vs. 1.5 Weeks:

Definitive layers are less visible in our large containers (perhaps due to their non-cylindrical shape?), but there is significant visible growth compared to the containers at 1.5 weeks. Additionally, upon closer inspection both red and green splotches can be found in the container.

Simulating Soil Conditions – 4 weeks:

At first glance, the container that we covered to simulate soil conditions looks similar to the uncovered columns. However, there is a small white strip at the top of sediment that we don’t see in the uncovered columns. There also appears to be a biofilm growing along the sides of the container.

As well as the beginning of a layer floating on the top of the seawater in the container.

Experimental tubes at 3 weeks (where we added either Potassium Nitrate or Ammonium Acetate):

From left to right: Ammonium Acetate Added, Potassium Nitrate Added, Nothing Added

We decided to keep one vial where Ammonium Acetate was added and one vial where Potassium Nitrate was added in complete darkness.

From left to right: Dark Potassium Nitrate Added, Light Potassium Nitrate Added, Light Nothing Added

Notice the difference in the amount of bubbles between the vials under different light and chemical conditions. All three of these vials have seawater from the same location.

Often when microbiologists begin to explore an unknown (or relatively unknown) environment, they begin by using classical microbiological techniques to try to characterize the communities of microbes living in that environment. These classical techniques are often referred to as “culture-based” because they are oriented towards the goal of trying to grow (or culture) microbes in the lab. Although culture-based techniques can be limiting (it’s nearly impossible to culture every single organism in any given environment), they are very useful for laying the foundation for the non-culture-based techniques the Seagrass Microbiome project will be using.

As a result, we in the Eisen lab have been playing around with some classical microbiology techniques alongside our non-culture-based explorations. One of the coolest techniques we’re using is Winogradsky columns. Winogradsky columns are essentially microbial terrariums. The basic recipe is as follows: take a clean tube, add a few essential chemicals, spike in some wild microbes, close the lid and let natural nutrient cycles take over. If you’ve done everything right, in a couple of weeks, you should start to see layers of microbes each living in a different mini niche within your mini ecosystem.

Two weeks ago we did just that. We’ve been following the progress of the tubes on the side as we pursue other non-culture-based projects. We’ve also been exploring different ways of making the columns to figure out the best way to get clean layers while still preserving the integrity of the column. Below are some pictures of our progress to date:

Two Days in:

One week in:

1.5 weeks in:

9 Days in:

2 weeks into the experiment: 

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