Bacteria Made Your Lunch

Cows that house bacteria


I was thinking of doing a post with a title like ‘In defense of cows’ or something along those lines.  This is not just because I’m a sort of carnivorous and contrarian guy (which I am), but because cows can actually do something that is objectively remarkable.  I know that lots of the readers on this blog are vegetarians or even vegans, and that is fine as a life-style choice for you. But no matter what your personal food choices are, it is worth thinking about what cows can do for the rest of us.

What Cows Do

One of the most abundant natural, organic chemicals in the world (cellulose), is something we humans can’t digest at all.  Cows are cool because they can eat cellulose and turn it into human-edible foods like milk and meat.  The reason that I switched the title of the post is that it isn’t actually the cows that should get the credit for this feat, at least not most of it.  Cows (and other ruminants like sheep, goats, bison, camels, llamas, yaks, water buffalos…) can only make this conversion because of the bacteria that they house in one of their stomachs.  In the whole world, there are only a few bacteria and a few fungi that have the capability of turning cellulose (the main structural polymer of all plants) back into the energy-rich, glucose sub-units of which it is made (bacteria also do that job for termites!).

I can relate to why many people have ethical issues with aspects of how beef or milk is produced today. But that does not, at least for me, mean that we should abandon the idea of harnessing the remarkable microbial process that has allowed ruminant animals to be such an important part of the human food supply in diverse cultures for millenia.  In fact I would like to see us refine not just the “animal wellness” aspect of this industry, but also its greenhouse gas issues.  

What We Wish Cows Didn’t Do

The climate change “down-side” of ruminants is that they are an extremely important source of the potent greenhouse gas, methane.  Some of that comes from the manure they generate, but at least there is a well developed technology for that could turn that waste stream into “carbon-neutral” energy using methane digesters.  Much more of the methane comes from the cow’s “burps” and some from “flatulence.”  This is true of both “range fed” and “feedlot finished” animals.  The methane is generated by non-beneficial bacteria that also live in ruminants stomachs and which are actually robbing the animal of some energy and making this problematic greenhouse gas at the same time.  We need to figure out how to safely reduce or eliminate this inefficiency through feed management, probiotics or something. I’m not an animal scientist, but I know those folks are working on this problem.

How We Get Protein

But the good, ruminant bacteria aren’t the only ones making our collective lunch.  Just as cellulose is a huge energy source unavailable to humans without the help of bacteria, nitrogen in the atmosphere is a huge, but mostly unavailable source of what it takes to make the protein we need.  Once again, there are a small number of bacteria that are able to turn the seemingly inert, di-nitrogen (N2) in the air into the forms of nitrogen that can be assimilated by plants (nitrate, ammonia, urea…).  Some of this occurs in aquatic systems by cyanobacteria and we benefit from it through the food chain it supports.  Some of it occurs through free-living bacteria like Azospirillum that lives on the surface of tropical grasses like sugarcane.  

Picture of an alfalfa nodule

The main way that we humans benefit from these remarkable bacteria is through the services of “legumes” which are plants that form a symbiotic relationship with a “nitrogen-fixing” bacterium called Bradyrhizobium that provides the plant with biologically available nitrogen in “trade” for the glucose that the plant can make using solar energy.  World-wide, farmers take considerable advantage of these bacteria to be able to grow crops that don’t need much, if any, added nitrogen fertilizer. I looked up the FAO statistics on global crop area, and 18.5 percent of the land planted to food crops are legumes even without considering animal feeds like alfalfa.  

We can’t get all our nutritional or food enjoyment needs from legumes.  Ruminants have their place in the food supply, but it is not all we need.  Still, as a “technology guy,” I’m humbled by the contribution that these “lowly” and ancient bacteria make to our survival. No matter what your food choices are, we all depend on bacteria.  

You are welcome to comment on this post or to email me directly at

Legume nodule image from ninjatacoshell

Cows image from jrubinc




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19 thoughts on “Bacteria Made Your Lunch”

  1. Humans might have a dominant advantage in making tools and using external energy sources, but plants and bacteria are still way ahead of us when it comes to sophisticated organic chemistry.

  2. I enjoyed this post… though I think there are a couple things that need further consideration.

    Most of the cows that people eat, in industrial-agriculture countries like the US, DON’T eat grass. They eat corn: lots and lots and lots of corn. To grow that corn, and to keep the cows confined in order to PREVENT them from around eating grass (so they’ll be fat enough to slaughter faster) causes GINORMOUS amounts of environmental pollution and soil degradation. Food animals raised in these conditions generate about 130 times as much raw sewage as the whole human population of the US– without the benefit of any kind of waste treatment systems. Since the rise of GMO crops (corn chief among them), the amount of pesticide use has skyrocketed (by something like 383 million pounds, per a 2009 study). That pesticide ends up in our groundwater, and in the cattle feed, and in your meat. Not cool, on many many levels… so yeah, it’s neat that cows can do this, if you’re a pioneer trying to farm 50 acres with 2 adults & 4 kids & no outside support… a creature that can turn grass into protein is great for that scenario. But that’s not where most families in developed nations are coming from, and not something our beef cows are typically allowed to do.

    The other problem I see is with the poor use of resources, in converting vegetable to animal protein– for any mammal, and especially for cows… it’s great that cows can do this, sure, but is it the best use of farmland? Nope. Not for any grazing animal, in a developed country, and worse for cattle than any other animal traditionally raised for food. Most of the energy from the grass gets used for the cows’ own metabolic processes. Compared to the same amount of vegetable protein raised on the same amount of land, cows produce about 1/8 to 1/10 as much protein… pretty wasteful use of resources, it seems to me.

    I personally think cows are cool… no argument there. I don’t eat them, myself, partly (though not wholly) due to the points I raise, above; but I don’t presume to tell others what foods they should or shouldn’t make. However, I do think that if you’re trying to make the argument that there are good environmental reasons to eat cows… hmmm… I don’t think that holds up very well at all.

  3. Evz,
    My point is not that the way we raise cows today is great (though it is not as bad as you describe). Actually most cows start off grazing and are “finished” in feedlots. This is all driven by economics. I would like to see a “better beef” option available to consumers that would include wellness and environmental impact improvements scientifically applied so that the price premium does not need to be too large (so that it can be a significant part of the market, not a tiny niche like Organic). As for the big increase in pesticide use – everyone seems to forget that there was a huge increase in crop commodity prices in 2007/8 and farmers responded by planting more and taking better care to limit pest losses. Lots of the chemicals that got used more are actually low in toxicity and have good environmental fate profiles. They were instrumental in generating the big harvests that not only reversed the high prices, but ended the food shortages that were occurring in poor countries around the world.
    I will agree with you that vegetable protein is a more efficient use of land and I have been increasing my consumption of it and reducing my meat consumption in terms of meals and portion size. That sort of change could make a big difference and is something that more people would be willing to do than to become vegetarians.
    As for the raw sewage generated by farm animals, at least during the feedlot stage the best option (and one that actually is done to some extent) is to put that manure through an anaerobic digester to generate clean energy. That is just one of many changes that could become part of a “better beef” product line.

  4. Nice to read a post that doesn’t make eating meat sound like the work of the devil. I am against factory farms and agri business in general but eating meat is not the problem– mass producing it is. Now how about putting those bacteria to work on the methane or using the methane to power tractors or something?

  5. I don’t claim to be an expert on cattle ranching, as I’ve never done it… but I have done a good bit of looking into food sources, sustainable & otherwise, in an effort to think things through & make the most informed decisions possible.

    From everything I’ve read (& not just from one type of source), it seems like corn-not-grass *is* the predominant cattle food in the US… though I’m sure the demand for grass-fed beef has risen in recent years (& I think that’s a good thing). I think ‘more pesticide is better’ is a pretty tough sell, from either health or environmental perspectives… and most of those ‘increased yields’ don’t seem to make it to impoverished parts of the world; they seem to primarily make it into animal feed, for meat-based dietary habits of developed countries. I like all the ways to make CAFO’s ‘less bad,’ environmentally, by recycling manure into energy… but ‘less bad’ is still a far cry from ‘good’, imo.

    I definitely agree with you, that there are ways to reduce environmental impact other than all-out vegan/ vegetarian eating… and I think it’s great that omnivores are thinking about eco-issues too. You are absolutely right that these issues are driven by economics: food production changes when consumers demand (and reward) it… so it’s great to see so many people becoming interested in these issues, whatever food they choose to eat!

  6. Evz,
    I think this must be a topic of interest to people. This post has already had over 700 page views since I put it up late last night. Thanks for the positive comment about omnivores!

  7. A few points in regards to your post Steve…

    “Lots of the chemicals that got used more are actually low in toxicity and have good environmental fate profiles.”.

    Not true. Atrazine is the most widely used pesticide in the United States, and also by far one of the most toxic. I guarantee that these farmers in question, statistically speaking, used a considerable amount of this chemical in the ‘manufacturing’ of their crops. Farms, just like corporations, are concerned with the bottom line.

    Secondly, the feedlots you claim to “not be as bad as you think”, are in fact one of the worst possible imaganings of where we can harvest these cows. With the amount of waste and the proximity to said waste these cows are subjected to leads to a breeding ground of infection and illness (not to mention the damaging effects of Bovine Growth Hormone, which is used in the majority of cattle farms in the country). One of the ways these corporate farms address the issue of disease is by administering high doses of antibiotics, which have been atributed to the increase in the number of disease-resistant strains of bacteria permeating through livestock.

    As I said before, the majority of the dairy and meat produced and marketed in this country is from corporate farms concerned with one thing: the bottom line. Whatever will yield the highest efficiency and generate the largest profits is the “right choice”, even if that means using harmful chemicals that not only infect the cows and crop but the populace the sustains themselves from it.

  8. you are a retard “lets address the greenhouse gas issues” That is the single most idiotic comment i have ever read. Are you aware that the meat industry by means of animal feces produces less that 1 percent of all greenhouse gases. You narrow minded global warming freaks need to stop listening to the propaganda. Like i said your an idiot.

  9. Ravi,
    You are right that producers make their choices based on the bottom line, but this is not a highly profitable business. It is extremely competitive and the profit margins are low. A company, corporate or not, has to make “bottom line decisions” or it is out of business.

    I don’t know how many consumers would be willing or able to pay more for meat produced differently. It would be interesting to see a poll on that, but usually consumers don’t actually do what they say they would do.

    As for Atrazine, it is definitely not “by far one of the most toxic” pesticides used. It’s acute toxicity is only a little higher than table salt.

    It has been under scrutiny for a long time and is under EPA review again this year. We will see what happens.

  10. Well, Don, I guess I will have to stand by my comment even if it is “the single most idiotic thing you have ever heard.” When you combine the methane that cows burp with that from the manure it is one of the larger sources from agriculture. That is a small part of the overall greenhouse gas picture, but my reasoning for wanting to see it addressed is that it would make feed conversion more efficient and it would generate a source of non-imported fuel that the farmers could use to reduce their costs. I don’t think that sounds “idiotic” at all

  11. I hate to say it: I agree with Steve!

    Don, wow, your comments are unproductive… debate isn’t so much about calling people names as exchanging ideas… You’re just saying ‘oh, yeah? well you’re stupid!’ without providing any ideas or arguments in support of any point you’re trying to make. Why even post? Is this 2nd grade recess, or what?

    Raising cattle, at least in an industrial situation (compared to a couple of backyard cows in Nepal or something) clearly *does* contribute troublesome emissions into the atmosphere… according to a 2006 report by the Food and Agriculture Organization of the UN, animal agriculture is “a major player” in climate change and “a major threat to [the]
    environment”– generating 18% of human-origin greenhouse gasses (much more than cars, SUVs, & other vehicles). Sooo… I don’t think Steve can really be faulted for bringing the issue up, in an article about cows.

    It’s hard to understand, though, why you’d be so offended by it! Could it be that everyone who sees things differently than you *must* be ‘a retard’? Wow, what a well-thought-out argument. <-(sarcasm!)

  12. @ravi This reminds me of Steve’s first posts on the site where he mentioned those “benign herbicides” *LOL* I guess that comes with the territory having worked for DuPont.

    @don I believe the green house gas issues invovled in meat production are in the production of corn and soy which are then fed to the animals. As well as all the forest (and rain forests) cleared. It doesn’t help that the feces from CAFOs create even more pollution in both the air, ground and water.

    I wouldn’t complain at all if companies were forced to pay for the externalities of their actions. I can’t pollute my neighbor’s yard with animal feces, why can a corporation?

  13. I just want to say, thanks Georgia. You will be a laboratory for what it means to go into total denial of our need for guest (yes, guest) workers.

    @Greg below. Yes, things like Roundup are “benign,” in comparison to erosion and pollution causing tillage. Actually, roundup ready crops were a disaster for DuPont. Their ALS inhibitors were all displaced. Before RR crops the herbicide group at DuPont was actually predicting that it would no longer be necessary to look for new herbicides. Um, NOT.

  14. Oops, forgot to say that I’m really sorry for the losses that the Georgia farmers will sustain until sanity is restored. The prisoners don’t seem to be able to do the job. I’ve got a detailed suggestion here (read down about the middle of the second post)

    for how to solve this problem, and maybe your troubles will get people to listen

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