A2: Microbes in the news

Article title: Behind the iron curtain: How the methan-making microbes kept early Earth warm Behind the iron curtain: How methane-making microbes kept the early Earth warm


Date: Arpil 17, 2017

Article author was not listed but the research’s author was: m S. Bray. The article was provided by the Georgia institute of Technology.

Source: Phys.org

Link: https://phys.org/news/2017-04-iron-curtain-methane-making-microbes-early.html

Assignment author: Morgen Southwood


Marcy Bray and his team simulated early earth conditions to try and explain why the oceans could be liquid in the first two billion years. The prevailing theory is that methanogens provided enough methane for the green house effect to maintain liquid oceans. The problem with this theory is that, as we learned in class, methanogenesis is an inefficient system, and can be out competed when alternatives are possible. One major competitor in this time period was the rust-breathing microbes, they would dominate any environment when iron was available. The term iron curtain, refers to the potential for rust-breathing microbes to repress methane emissions when rust is plentiful. If methane was completely suppressed then the planet would likely have cooled. The microbiologists simulated early earth to study microbial diversity and methane emissions in varying conditions. They found that in iron free pockets of the oceans, methanogens could have thrived and been enough of a source of methane for keeping early Earth warm.


This article strongly related to our lectures on the methane cycle It also related to some exam 1 material, when we learned about the ferrous and ferric iron signatures that signaled changes in early earth microbial diversity.

Critical analysis-

This article could have used some more explanations. I understood the conclusions it drew, but I wouldn’t have been able to without material I learned in this class. I would have needed someone to fill in the blanks for me. It was important to understand why rust-breathing microbes would have outcompeted methanogens, and the significance of shifts in microbial diversity with different conditions etc. The article assumed/required the reader to know this supplementary information, and therefore it was not accessible to the general public.  I think the article was scientifically accurate in the way it described the idea proposed by the results of the study, however the title is misleading. The title seems portray that the study was a confirmation, when it was only supportive of the idea.

Since I did have some background information, this article was very interesting to me. When I thought about the major shifts in microbial diversity of the planet , I always thought about microbes relating to oxygen. These rust breathing microbes and methanogens were just as important stepping stones in shaping the Earth.


The conclusion of the article is that methane emissions could have come from microbial communities that were in rust free patches of the ocean. I thought that the ocean was well mixed. How could there be sections of the early ocean that were so poorly mixed that they lacked iron, while other areas had high levels of iron?


Newly Discovered Microbes, May Explain the Origin of Complex Life

Source: Mike White of TrendinTech

Date: 13FEB2017

Link:  https://www.trendintech.com/2017/02/13/newly-discovered-microbes-may-explain-the-origin-of-complex-life/

Summary: A team of scientists discovered a new archaeon that could be the closest living relative to eukaryotes.  Four lineages total have been found so far that fall under the Asgardian classification (the name given to these archaea).

Connection: We’ve discussed the lineage of bacteria, archaea, and eukaryotes and how they are similar/different.

Analysis: As far as relating to a crowd unfamiliar with microbiology, I felt this article did a pretty decent job in explaining some background.  They for instance give a brief description of Earth and how early Earth did not have eukaryotes, and then go into how they are and could be related.  They also hypothesize that these Asgardians are a possible precursor of sorts to eukaryotes. They even provide a picture demonstrating this.  It was also interesting to note that these archaea have been found all over the world, not just in a single localized area.

Question: The article did not go into great detail, but it made me curious as to what exactly these archaea in particular have in common with eukaryotes.