A2: Microbes in the News (Post 3)

Genetically engineered microbes make their own fertilizer, could feed the world’s poorest

Source: Science Magazine

Date: April 4th, 2017

Link:  https://www.sciencemag.org/news/2017/04/genetically-engineered-microbes-make-their-own-fertilizer-could-feed-world-s-poorest

Summary: Currently, big chemical  plants use nitrogen and methane to make ammonia (i.e fertilizer), which is not typically a viable option for developing countries, not only because they are expensive to run and maintain, but also because they lack the resources to distribute the produced fertilizer.  While we know of some microbes that are capable of nitrogen fixation, researchers from Harvard have genetically engineered a bacterium to be able to convert nitrogen (N2) to ammonia or other forms that plants can use, with the hope it could be used on a widespread commercial scale, which India has started to work on.

Connections: Throughout the semester, we have learned about and tested the physiological capabilities of microbes. We did test to see if our microbial isolates were capable of denitrification (whether it be partial or complete).

Critical Analysis:  I do think this article was scientifically accurate and it did answer some of my questions (how/where does the energy for this come from? what enzymes are involved in the process?). However, the article does fail to discuss the fact that there are existing microbes that convert N2 to ammonia or nitrates/nitrites and does not explain why this specific genetically engineered bacterium is better than any of the preexisting microbes capable of this same process. It conveys a message that this is somehow a new concept, even though it is not. It also discusses the scientific conclusions  that the genetically engineered bacterium,  Xanthobacter autotrophicus,  works outside of the lab because  the researchers put it in solution,  watered  a sample of radishes with it, and noted  the radishes grew 150% more than the controls. They did this in the lab though. I’m not saying this conclusion isn’t valid, just that it doesn’t sound as if anyone has attempted to replicate this, or test this in an environment with several other factors that a lab cannot account for. They have a ways to go before this could lead to feeding the worlds poor. Overall, I think the author means well and conveys the science itself fairly well, but misleads the public as to what exactly the science means in the grand scheme of things.

Question(s):  If we’re wanting to commercialize nitrogen fixating bacteria, why not use one that does not require genetic modifications? Do  Xanthobacter autotrophicus  have greater diversity in the environments in which they can survive/thrive (i.e a variety of climates)?

2 Comments for “A2: Microbes in the News (Post 3)”



This is an interesting article! I agree with you that it could be misleading in that someone reading this could think that the only way to use bacteria to fix nitrogen is to use genetically engineered strains. I also thought that even though they are talking about feeding the world’s poor, they really don’t mention how much cheaper this method would be. There certainly should also be research into using existing strains of nitrogen fixing bacteria to help with food production in poorer countries.



It was pretty odd how the article made it seem like nitrogen could only be fixed by their modified methods. There’s so many different species of microbes that can already do this. I can see how the article is a little misleading in this way. I think the article is tailored to people who know a lot less about microbes than us. They have a target audience that isn’t as knowledgeable as our class. Taking this into account, I think there could be many different reasons for using genetically modified microbes instead of the ones that already exist. A genetically modified microbe could withstand more extreme conditions and habitats than bacteria that already fix nitrogen. Maybe the modified ones reproduce faster or will have a higher productivity rate. They could design a more efficient microbe.