Microbe Spotlight: Week 6

NDSU Microbiology
by NDSU Microbiology

Pseudomonas putida CBB5

We are a world that runs on caffeine. But did you know that there is a bacterium that is a caffeine addict as well? Pseudomonas putida CBB5is that addict. It was discovered by Ryan Summers, a Ph.D. student at the University of Iowa. He was sampling soil from around campus and isolated this bacterium. When he ran some tests on it, he found that when grown in a pure caffeine medium, the bacterium was able to grow and thrive. This is because it can use an N- demethylation pathway to break down the caffeine into uric acid. He also found that this bacterium could break down theobromine and 7-methylxanthine, which are two other molecules that bacteria are not usually able to utilize.

From this, a research team in Austin, Texas came up with an idea to use these novel genes for good. They knew from research that the world’s water supply was becoming caffeinated due to all of the waste from our drinks and pharmaceuticals. They transplanted the novel caffeine genes into a strain of E. coli in their lab. They found that these E. coli mutants could be used to decaffeinate the water supply. The long-term goal of this research is to develop a new form of bioremediation and help clean up our water supply in a safe way.

By Katie Sanders

Image: CDC/Janice Haney Carr

Pandoraviruses

Pandoraviruses were very recently discovered by French scientists, Jean-Michel Claverie and Chantal Abergel, and their report was published in July, 2013 in Science. These viruses were discovered by studying the death of acanthamoeba in water samples. Pandoraviruses have the largest genome of all known viruses, with up to 2,500 genes. Only about 6% of the genome has recognizable relation to genes of known organisms, the rest is very unfamiliar. These viruses are also exceptionally large in size, measuring approximately 1 micrometer in length and 0.5 micrometers in diameter. They are second in size only to the recently discovered Pithoviruses, which measure 1.5 micrometers in length. These viruses are so huge they can be seen under a regular light microscope.

Pandoraviruses are only known to infect amoebas. At this time, they are not known to be pathogenic towards any other living thing. There are two species, Pandoravirus salinus and Pandoravirus dulcis. P. salinus was found off the cost of Chile and has 2556 protein coding sequences, while P. dulcis was found in a pond in Australia and has 1502 protein coding sequences.

Another interesting fact about Pandoraviruses is that they don’t reproduce like normal viruses. They use a newly discovered process called “knitting” to replicate. Pandoraviruses and other enormous viruses such as Mimiviruses or Pithoviruses don’t fit into the eukaryotic, prokaryotic, or archaeal branches, suggesting there is a
missing branch on the tree of life. Some scientists argue that we reevaluate the tree of life in light of the recent discovery of these massive viruses.

By Emily Norwig

Image: Ghigo E, Kartenbeck J, Lien P, Pelkmans L, Capo C, Mege JL, Raoult D; Licence

Cordyceps

Ophiocordyceps unilateralis (commonly known as Cordyceps) is a fungal parasite that can infect and kill ants. It specifically infects Camponotus leonardi, better known as "carpenter ants." The natural habitat of this fungal microbe is found predominantly in a tropical ecosystem. The interesting feature about these fungi is that when coming in contact with their host, they produce enzymes and with the help of some mechanical force, these enzymes enter into the ants. A week after that, the fungus infects the ant’s brain by producing toxins. These toxins can control and manipulate ant behavior, making ants leave their tribe and migrate to a place that is best for fungal growth. After that, the fungus kills the ant and starts consuming the ant’s internal organs. The medical aspect of this organism is that this fungus produces chemicals that have anti-malarial properties and potential to be new antimicrobial agents.

By Jiyan Mohammad

Image: Ian Suzuki; License

Myxococcus xanthus

Myxococcus xanthus was discovered in 1892 in top soil that is damp and full of organic matter. This bacterium is Gram negative and rod shaped. It is often referred to as the "wolfpack” microbe because of its social behaviors of swarming, predation, and development.

Swarming is triggered when nutrients run low. The bacteria move together by S-motility gliding, which is the movement of large cell groups that creates fruiting bodies. These fruiting bodies are made up of thousands of cells that secrete hydrolytic enzymes into their environment to lyse other cells and convert insoluble proteins into soluble transportable amino acids. The swarming growth and impact of genetic deletions are based on the members in the Frz proteins. These proteins set a reversal frequency and are connected in a negative feedback loop that activates the G-protein to go between GTP and GDP bound states and determine whether the cell is moving forward or backward; this reversal eventually leads to alignment.

M. xanthus adapts and hunts other soil bacteria under both starvation and ideal growth conditions. Predation and development both induce rippling motility behavior,
which is the organization of cells into moving groups that resemble the movement of waves rippling on water.

By Kara Mauch

Image: Trance Gemini; License


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