Wednesday, February 7, 2018

The “Bugs” We Depend On

Only about 1 in 10 cells in our bodies is human, the rest are bacteria. Some of them are good and help us stay healthy. Bacteria interact with plants in the same way that they do with humans, providing opportunities for their growth and health.

"I remember that before I started studying and practicing microbiology, I would have heard the word “bacteria” and immediately associated it with something bad. The truth is that the “good” far outnumber the “bad” when it comes to these tiny living organisms. Also known as bacteria, microbes, microorganisms, or in lab-speak “bugs”, these creatures make up far more of our world than we are aware of."

Sarah Hovinga,
Senior Scientist,
Biologics Project and Product Support, Disease Management,
Bayer Division Crop Science

If you take the average human body, for example, and you subtract all of the human cells, you might see a ghost-like figure in front of you simply due to amount of bacteria that live in and on our skin, hair, guts, faces, and mouths, among other parts. Only about 1 in 10 cells in our bodies is human - the rest are bacteria. Initially, someone could squirm a bit at this thought, but believe it or not, we NEED these “bugs”. Sterility is a bad thing when it comes to competing in the natural world. The more “good bugs” you have on your side, the better.

So why are these bugs good again? We naturally have trillions of microorganisms living inside our guts and they are an essential part of digestion, for example. Let’s take the example of a bacterial genus and species called Escherichia coli, a.k.a. “E. coli”. AHHH! Right? It depends. Most of these guys are benign, and some even necessary for our health. There are some strains, however, that affect us as humans in a very bad way, perhaps the most infamous one being E. coli strain O157:H7, the strain being linked to food poisoning outbreaks. This strain has made newspaper headlines at least more times than we would like, and not in a good way. But on the whole, all of the non-human pathogenic strains of E. coli either don’t cause us harm, or are essential to stabilizing a healthy population of microbes in our stomachs.

So what is meant by “strain” anyways? Understanding this is key to understanding why some are good and some are bad. A good place to start is to think of different strains of bacteria like different human beings. We as humans all share the same genus and species, Homo sapiens, just like all E.coli do: Escherichia coli. Some humans contribute to society in a good way, and some, unfortunately, don’t, and others are the stabilizing forces that keep our society afloat. If you think of each individual person as a strain, the picture of different strains of E.coli starts to make sense. Now we begin to understand why most are good and only some are bad.

Microbes are usually much smaller than the human eye can see.  Most are on the scale of micrometers. The best way to see them is usually with a microscope or by "plating" them out onto growth media and allowing them to grow into a large "colony". Each opaque white dot on these Petri plates is considered a colony, and in theory each one began from one single cell. This method of estimating "Colony Forming Units", or "CFU's" is one of the most standard methods in microbiology.

This image shows beneficial bacterial colonies alone (top 3 plates) and these same beneficial bacterial colonies challenged with a common plant pathogen, Botrytis (bottom 3 plates). This is the mold you often see growing on your strawberries that sat too long in the fridge.  Botrytis affects far more than just strawberries, though, it is one of the major headaches of crops most enjoy, such as grapes and cherries.  Here we see the opaque beneficial bacterial colonies directly defending themselves against this destructive plant pathogen.

Beneficial microbes aren't just bacteria, here we see two different strains of one of the most common beneficial fungi around, Trichoderma.  In my opinion fungi are much more visually interesting to look at than most bacteria - for instance, look at this green!

Let’s take some more examples of the “good bugs”. Yogurt. Glorious yogurt. Part of my daily diet, I pack my stomach full of this every morning. Yogurt is a mixture of beneficial bacteria that do all sorts of good things. These good guys grow inside of your gut, colonize your stomach lining, and excrete all kinds of good biological chemistry that helps to process food, helps to promote a healthy microbial community, and even affects how your stomach talks to your brain. What other things do we depend on microbes for? Beer, wine, cheese, soy sauce, chocolate, bread, coffee, vinegar, salami, and the list goes on. As it turns out, we depend a lot on these tiny “bugs”!

In general, microorganisms interact with plants in the same sort of way that they do with humans. Providing opportunities for plant health, among other beneficial effects, these bacteria already are and, as we continue to understand their effects, will develop into even more powerful little tools in agriculture. Needless to say, I no longer associate bacteria to bad things because I now understand their beneficial impact in life. Studying the use of microbes for agriculture is where I began my professional life, and if I had to guess, it is where I will end my career since their ubiquitous use in how we grow food is inevitable, in my opinion. In a way, I think it’s funny to dedicate your life to something that you can’t even see. But with microbes, the benefits they provide are TNTC (TNTC = “too numerous to count” – sorry, a little microbiologist joke).

And if you’re interested in learning more about microbes and their use in agriculture, there are a lot of really good people out there doing amazing things. For example, some of the work being done at Bayer can be seen here:

Beneficial Bacteria and Soil - Hidden Helpers Below Ground

Empowering Plants to Protect Themselves

Integrated Solutions for Vegetable Crops - Innovations for Diversity

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