Lab 6: Microbial Art – Alaska Scenery

Danielle Bohan, Lab F03

My artistic intent was to portray what I love about living in Alaska, which is mainly the beautiful scenery and solitude Alaska has to offer. My art piece on the Eosin Methylene Blue (EMB) agar, as seen above on the left,  didn’t turn out exactly how I had envisioned but I think it portrays the aurora and mountains with snow decently enough. The right image explains the bacterial species used and how I expected the colors to turn out. I think given more time, the bacterial pigment would appear more vivid but the image itself may appear less sharp so I decided to snapshot the EMB agar 3 days post inoculation.

The EMB agar is differential because it contains a pH indicator, eosin, that allows us to visually see whether the bacteria ferment the sugars available in the agar or not. Eosin will turn from colorless to red/black in a low pH environment which indicates that the bacteria have released an acidic product as a result of fermentation. The only bacteria used on my EMB agar that has fermenting capabilities of lactose/sucrose is E. coli, which has a strong capability of fermenting lactose. This turned the mountain top/outline to be a dark color. I also used it in the aurora  because I thought it would create a green sheen, but for some reason, it grew as off-white/pink. I am not sure if this is because it is encased between two other bacteria and they may be limiting the E. coli’s  ability to ferment the sugars available. I added the E. coli to the mountain tops and immediately after added the E. coli to the aurora, so I know I didn’t  make a mistake by adding an unintended species. Perhaps if I had given the plate more time in the incubator, I would have seen a similar resemblance of the E. coli on the mountain tops and the E. coli in the aurora. The rest of the bacteria used are non-fermenters, so the color that is seen in other areas is due to the pigment of the bacteria themselves.

I would also like to add that when I was choosing which bacteria to use, I made sure to use only gram-negative bacteria since the dyes used in EMB and the MacConkey agar inhibit the growth of gram-positive bacteria, which makes EMB and MAC selective media.

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