Munching on methane

Just over two weeks before we head to Europe on sabbatical. Dr. Dave is prepping my documentation. I had a rabies shot, 2 weeks ago or so, I have a new name tag, and I have to go back to see Dr. Dave for my wellness exam, before the USDA signs off on my medical certificate.  Phew.

Mufasa and I at a water fountain in Mosier

 In the meantime I met a young Leonberger, Mufasa, and we played and shared some water.  I tried to tell Mufasa about a recent discovery that was reported in Nature Geosciences journal. Because I still smell skunky when I get wet, it reminded of the article by Saito et al., 2013, DOI: 10.1038/NGEO1893 in Nature Geoscience that I read recently. Recall in a previous blog I made the analogy of the skunk tail-a plume- and then the skunk spray- also a plume ... with deep-sea hydrothermal plumes. Well, a new  hydrothermal plume with very high iron was discovered in the Southern Atlantic. In our oceans iron is a very important micronutrient in photosynthesis and nitrogen fixation, so estimating how much iron exists in our oceans has important implications, even for such factors as global climate. Much of this iron is derived as seawater circulates through the Earth's crust and is again released as hydrothermal fluid at deep-sea vents. Because we haven't studied many of the global deep-sea vents, and especially not the slow spreading ones like those in the southern Atlantic ocean, helium-3 concentrations have been used as a proxy (tracer) for hydrothermal activity in our oceans. Now what Saito et al found from iron  measurements in the plume that they discovered was that the helium proxy potentially grossly underestimates the hydrothermal input of iron into our global iron biogeochemical cycle. Other approaches for estimating iron, like models, in concert with helium measurements will in the future provide greater insights into the global fluxes of iron in our oceans. Unfortunately Mufasa wasnt really interested in this. I guess he's just 18 months old, so too young to understand ...

But just to illustrate how little we know about global biogeochemical cycles, Haroon et al., report  in Nature 500:567-570, the discovery of a novel archaeal lineage that couples anaerobic oxidation of methane (AOM) to nitrate reduction. AOM is a very important global biogeochemical process, as it reduces the release of the potent greenhouse gas, methane. Although the process has been known to occur for over 35 years, it has only recently been shown how microbes can do this energetically difficult task. And they can do this in a number of ways.. by coupling sulfate reduction to methane oxidation sometimes alone, or sometimes in collaboration with each other, or through through AOM coupled to denitrification. But if that isn't complex enough, Haroon et al show that yet another archaeon can also enjoy 'eating' methane with others by directly coupling AOM to nitrate reduction.   If ammonia is also present they get a little help from a bacterial anaerobic ammonia oxidizer friend, who keeps the other denitrifier (who is able to couple AOM to denitrification) at bay.  I do wonder if I have AOMs in my gut?  Probably not.

Recently, I have also been bossing my friend Albie around, training him how to clean faces. First you have to calm the subject. Then gently reach up to their face, but dont let them pull back. Here Albie, let me show you how.

Two other papers of note: Nature 500:541, Richness of human gut microbiome correlates with metabolic markers, and companion paper Nature 500:585, Dietary intervention impact on gut microbial gene richness.