Antarctic Blog 2013


photograph © 2013 Lorena Lagos Pailla and Leticia Barrientos

Day 13: Ardley Island (Isla Ardley), close but far away, and the difference in bacterial growth media (3.3.2013)

We're trying to get to Ardley Island in Fildes Bay today (-62 12 39.1, -58 56 24) but, once again, the weather is not cooperating. A cold 2° drizzle this morning here at Escudero Base with thick fog may change to rain and wind this afternoon. We'll see.

Ardley Island is actually very close to Escudero Base but if you can't keep a zodiac from flipping over in the wind, you can't get there. So Ardley is close but too far away for today. I was told that in the past, research scientists traveling in a zodiac that flipped out in the bay made it to Ardley island but weren't picked up before they froze to death.

Everyone at Escudero was deadly serious about their preparation for each expedition.

As the summer winds to its end here in Antarctica, the beginning of fall will offer an average March temperature 5° lower compared to February. At summer's height, temperatures here on King George Island rise to >20°C in January. At the "depth" of the winter, in July, low temperatures approached - 5°C. A 25 degree C spread is a 45 degree Fahrenheit difference.

While it appears that thick fog, cool temperatures and sustained winds have canceled today's sampling trip to Ardley Island, the culture enrichment experiments are getting exciting.

Below is a zoomed in photograph of two octrants of two different Te-amended agar plates. While each has 50 µg/mL added K2TeO3, one is a complex growth medium, LB, and the other a different, less complex medium, R2A. It appears that there are clearly two different bacterial morphologies for inocula taken from the same sampling tube, Sample B9, the soil from under the Antarctic grass Deschampsia one of only two flowering plants that are Antarctic natives. While the photograph you see here is not very clear, we think the following important:

1) The most obvious finding is that the low nutrient R2A medium has the largest number of apparent different microbial species. (By the way although we've got some fungal growth, nothing said here refers to fungi.)

2) The R2A plate octrant inoculated with sample B9 has more visually different bacterial colonies when looked at closely, i.e., different colony shapes, reflectivity, and border characteristics.

3) On the same plate, colonies with the same apparent growth rate, that is, same colony diameter, have different tellurite reducing abilities; some are black and some not. Since both the plates have tellurite added, everything that's growing must be Te resistant, but some microbes respond different from others: some produce Te0 and some don't.


Two plate comparison
Two-plate comparison of tellurium-resistant microbes
that produce elemental Te in aerobic growth on two different growth media


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