Ibrahim's blog

Week 5

            Before I blog about this week’s events, since people have been asking me about how I treat my microplastics (plastics 5mm or under) -- I wanted to let you guys know about the procedure I use. All the methods can be found on my blog (Week 2, February 2, 2018) and I’m happy to answer any questions anyone has.

          

           

Figure 1: Contaminated Pseudomonas stutzeri on PIA media plate. 

This week was a setback. Out of our sixteen plates (Pseudomonas species + plastic types 3,4,5, &6), four were contaminated. By now the team has gotten used to Pseudomonas stutzeri turning pink supposedly when “contaminated.” This happened twice last semester. We have two hypotheses to why Pseudomonas stutzeri and Pseudomonas putida change pigments to pink when growing. The first fair hypothesis is due to contamination of other bacteria species mainly Serratia marcescens, a common soil bacterium known to have a pink pigment. The second hypothesis came from an article I was reading from. Since Pseudomonas stutzeri is an aerobic (needs air to grow) bacterium when sealed with parafilm on media plates, it could’ve morphed/mutated (I know, cool huh?) to an unknown species. This could be true because Pseudomonas stutzeri is famous for denitrification (nitrate reduced to nitrogen). I’ll make time this week or the coming week to try and isolate this pink pigmented bacterium, and finally, have an idea of what we’re dealing with.