Of Maggi and the microbes

Few days back, I was sipping coffee and reminiscing about the days I spent in research laboratory doing various microbiology experiments. I miss those days. But then I reminded myself that I explore the marvelous world of microbes right at home! So, I decided to take matters into my hand :grinning:

The first thing that I had to decide is what can be a good well-rounded food source for growing microbes in my home-lab? I know CUBists have successfully used boiled potatoes for growing and isolating bacteria. However, I did not have potatoes at home. I brainstormed to find a quick “solid media” in kitchen that can supply a variety of different nutrients. One of the first thing that came to mind was Maggi 2-minute noodles, a part of about 70% urban Indian households.

To decide if cooked Maggi noodles can be used as solid media for microbial growth, I probed the nutrient content of Maggi per serving (i.e. one regular packet). Here’s what I found:

One packet of Maggi is approximately 70g and supplies the following

Protein: 272g
Carbohydrate: 41.7g
Total Fat: 9.5g
Sodium: 719.8mg
Iron: 4.8mg

By looking at the contents, I concluded that Maggi could supply most nutrients required to support microbial growth, plus iron which is an essential micronutrient. Hence, I started investigating if cooked Maggi noodles could be used as solid media for microbial growth at home.

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Step 1: Maggi media preparation and inoculation of samples

  1. Crushed one packet of Maggi Noodles in a microwave safe bowl
  2. Added 1 cup of drinking water to the crushed noodles
  3. Cooked the noodle in microwave for 4 minutes
  4. Poured the cooked noodle in the rectangular plastic box
  5. Spread the Maggi evenly with a clean spoon, covered with the lid
  6. Left the covered container undisturbed to allow Maggi to cool down and settle
  7. After 30 min, cut the Maggi into 4 approximately equal cubes and placed on individual aluminum foil spread on a disposable plate.
  8. Added samples to the Maggi cubes with clean sterilized cotton swabs.
  9. Covered the plate with large piece of aluminum foil and left on top of refrigerator for incubation at room temperature (approximately 21 degree Celcius).
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Due to technical difficulty in uploading pictures of my experiments, I am sharing the links to the files.

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So what do we see with the Maggi.! Is there anything that we can learn from it. DOes it work as much as the potato?!

If you click the link I shared above, you will see that I have 4 cubes of cooked Maggi noodles.
Control → Where I didn’t add anything
Kitchen Tap Surface → I swabbed the Kitchen Tap Surface with a sterile cotton swab and then swabbed the respective Maggi noodle cube with the swab.
Tap water → I dipped a sterile cotton swab in a spoonful of Tap Water and then scrubbed the surface of the respective Maggi noodle cube with the swab
Soil solution → I took a spoonful of soil from a plant pot, mixed it with two spoons of tap water, dipped a sterile cotton swab in the soil solution, and finally transferred the soil solution by scrubbing the surface of the respective Maggi noodle cube with the swab.

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Observation & Conclusion:
No visible microbial growth was observed post 24 and 48 hours of incubation, and the samples looked similar to their respective pre-incubation Maggi cubes. Since I did not maintain the temperature, and the night temperatures in my current city are around 13-14 degree Celsius, it is possible that slow microbial growth under low temperatures hindered appearance of visible microbial colonies on the Maggi cubes.

Post-72 hours of incubation, microbial growth was observed on all Maggi cubes, including the control where I did not add any sample.

  • All three cubes, i.e. control, kitchen tap surface, and tap water samples, had colonies of greenish molds on the sides of the cubes, and yellowish slimy patches on the surface. Growth on my control cube suggests that contamination did find its way into the system. This is not entirely surprising because my experimental setup was not exactly a closed system. I kept all the cubes on a disposable plate and covered the plate with aluminum foil. Therefore, the samples were in close contact and cross-sample contamination could have happened. Additionally, I removed the aluminum foil every 24 hours to take pictures of the samples on the plate and consequently exposed the cubes to aerial microbes.

  • Significant microbial growth was observed on the Maggi cube containing the soil solution. The entire side of the soil solution cube was covered with white cottony fungus and a small colony of pink fungi appeared on one of the corners. I did not notice bacterial colonies on the surface or on the side. There are a few possible explanation for these observations:

  1. Diverse microbial lives are abundant in soil, including many bacteria, yet in this experiment I mostly noticed only one or two type of fungal growth. It is possible that because I used a highly concentrated soil solution (as you can guess from the color of the sample pre-incubation), the fast growing fungi which were potentially present in larger numbers in the inoculum easily outcompeted other microbes by taking over the space and quickly utilizing the available nutrients. Therefore to enable growth of rare and slow growing microbial species from soil on the Maggi cube, I would try repeating the experiment with a diluted soil sample.

  2. The low temperatures negatively impacted the growth of microbes from soil on Maggi and consequently diversity of microbes growing on Maggi was really low.

  3. The lower microbial diversity on Maggi cube inoculated with the soil sample could also be due to the inability of those microbes to use the nutrients supplied by Maggi.

  4. It is also possible that all of the above three factors are responsible for low microbial diversity observed on Maggi cube inoculated with soil solution.

The other thing I noticed is that the microbial growth observed in each sample was mostly restricted to the side of the Maggi cubes and the surface of the cubes largely remained unpopulated. This is potentially because the aluminum foil covering the plate was touching the cubes’ surface and prevented microbial growth.

Together, these results indicate that Maggi could serve as a medium for microbial growth. However, I would have to design a more closed system to reduce contamination issues and facilitate microbial growth on Maggi’s surface by using a cover that is not touching the Maggi surface.

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@VijayVigyanShaala With the current experimental set up and samples used in this study, I am unable to comment on whether Maggi works as good as a boiled potato. CUBists had inoculated boiled potatoes with milk to grow and isolate bacteria, and I did not try to apply milk on Maggi yet. In future, I will inoculate Maggi cubes placed in closed systems (to prevent contamination) with milk and compare that with bacterial colonies found on boiled potatoes.

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