Biology 1610 Signature Assignment Article Analysis

Biology 1610 Signature Assignment Article Analysis

A Census-based estimate of Earth's Bacterial and Archaeal diversity Authors: ​Stilianos Louca , ​Florent Mazel, Michael Doebeli, Laura Wegener Parfrey

Article Analysis Summary Completed by Nania Platt April 4, 2019 To summarize this article, is a difficult feat. This article was a large part of summation of many research work put into one research article. A large part of this article was to inform readers about the diversity of bacteria and archaea. They did not however go into the details of each microorganism but simply was an overarching analysis of the data of many previous research work. The authors that had various degrees in the scientific research came together to help answer the question of what the population of prokaryotic organisms there are or were on the earth, globally which they call OTUs. Upon reading and trying to understand the material presented I found that their main objective was to promote that there were statically much less OTUs in the world than previously projected to the science world. There is still much to be researched on OTU populations globally but this article has done a huge amount of work to minimize errors and come to a more definite conclusion that there are roughly, 739,880 prokaryotic taxonomic units (690,747 bacterial and 49,406 archaeal), where they conclude that there are roughly 0.8-1.6 million prokaryotic OTUs and 2.4-4.3 million full-length OTUs worldwide. This claim is to refute the previous predictions that there exists trillions of prokaryotic OTUs.

Furthermore, this article's purpose is to come to a more complete estimate to the total population of prokaryotes, OTUs globally. And to do so the researchers had to compile all the previous attempts to summate the population of OTUs. A large part of their analysis comes from

GPC (Global Prokaryotic Census), SILVA, EMP, RDP, GTDB, UTB, IMG/M, and ASVS. Each individually are different researchers results and claims for the population of OTUs. The most inclusive or accurate according to the article is GPC and the others were taken to ensure that there were not any OTUs forgotten. Much of the work of each group brought about different or similar OTUs and the researchers compiling the work took into account each and kept the prokaryotes that were shown in more than one research. They put aside those that were only mentioned once. This ensured that the certain OTU being analyzed was account for and was accounted for many times in each or at least in two. With there being so many groups of data being accessed, there was bound to be overlap in data and that helped to ensure that those certain OTUs were accounted for.

In this way, the researchers also took the data they were analyzing by looking at the 16S ribosomal RNA gene area of the OTUs. This area in the gene helps to distinguish the differences between the prokaryotic cells that exist globally. They do note that they cannot possibly cover and analyze every species and variation but with the help of the previously research work, they can come closer to the more accurate estimate. And by taking out the cross overs or doubles found, they can more closely analyze those species that are less abundant. Also to note the census covers on data sequenced from 34,368 samples across 492 studies from 2,800 distinct environments.

As a result or way to formally compile the data, the article goes to show the information they gathered and analyzed is by three different distinct figures. They are explained in detail in the results and discussion section of the article. In Figure 1 is a depiction of all the data they recovered and put into a graph, it also depicts the overlap in information and how they analyzed.

Much of the information was also calculated by the Good Turing Formula. Based on this graph, their estimate is 3-9 million prokaryotic clusters that are found worldwide. This greatly refutes the estimates made before that there are trillions prokaryotic OTUs found worldwide. The second figure is to help for possible caveats in the information gathered. The two graphs shown, depict peaks that are to explain the abundance and scarcity of OTUs found in the data analyzed. Meaning there is variance in the data collected, but everything is being accounted for. And lastly the third figure is a representation of three different studies; SILVA, RDP and GPC data. Each help to explain the Taxon-Specific Diversities of the OTUs.

From the data researched and gathered, implications can be made that the overall estimate of the rich abundance of prokaryotic cells globally is about 6 orders lower than previously predicted as the article states. I also can see that the vast amount of their research had tried to be more specific on 16S gene as, it seems that some of the previous studies/research have not. By doing this there is a more direct way of totaling all the work that has been done and making room for more discoveries as they come or as the prokaryotes evolve. It seems that there has been a lot of research done but there are yet to be those to be discovered. Those discoveries can and will change the medicine world and how we view the world around us. There are far more species and diversities than one can even comprehend and there have been before us as well. With this research, it can change the world.

Reference to the Article:

https://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.3000106