One of my intentions when I started this blog is to show that microbes are everywhere. So what better way to do that than to share some of the ways we encounter microbes just by venturing outside? Taking a walk, or digging up some dirt, for example.
Here are four of the many ways to enjoy the great microbial outdoors.
Enjoy the scent of rain
Don’t you just love that fresh, post-rain smell? This rainy scent is brought to you by microbes, and their attempts lure springtails to spread their spores. Streptomyces, a soil-dwelling bacteria, produce a chemical called geosmin during sporulation. Springtails use the odor of geosmin to make their way to the sporulating colonies where they feed on them and disseminate spores elsewhere via fecal pellets.
When rain (also thanks to microbes!) hits the ground, geosmin molecules make their way into the air. We humans can also detect geosmin at low concentrations – five parts per trillion – giving us that lovely scent of rain.
Spot some lichen
Lichens grow on all sorts of surfaces: tree bark, rocks, metal, and many more. While the lichen may look like a single organism, it’s actually made of a collection of organisms including a fungus, a symbiotic photosynthetic microbe (aka photobiont), and other bacteria. For lichen, the photobiont is usually either a cyanobacteria or a photosynthetic eukaryote. The symbiotic partnership between fungus and the photobiont results in a mutually beneficial exchange. Through photosynthesis, the photobiont provides a carbon source to the fungus, while the fungus allows the photobiont to thrive in climates that they would not be able to on their own.
But, there’s been debate whether or not this relationship is a symbiotic one or whether it is controlled parasitism. Half of the carbon fixed by the photobiont gets immediately converted to fungal sugars that the photobiont can’t use. In the lab, scientists are able to put together fungi with photobionts they don’t normally associate with in nature and saw that the interaction becomes parasitic. Some lichens even parasitize on other lichens.
So the next time you spot some lichen, you’re witnessing microbial interactions in action.
Start composting
Save your produce scraps and start composting! During composting, microbes break down the complex organic matter into simpler organic and inorganic compounds. A good compost depends on many criteria: nutrient source, temperature, moisture, pH, and oxygen. But generally, composts involve feeding it with produce scraps and turning it.
That’s why many composters have tumblers that rotate to introduce more oxygen, and why compost piles on the ground get mixed with a shovel. You might also notice that a compost pile heats up as it sits out. This is because of the microbes hard at work! Turning the compost pile also distributes the hot compost so that it evens out the temperature.
While caring for your compost pile is generally similar, what you feed your compost could change the quality and purpose of the compost. For example, different types of veggie scraps used for feeding could make it more able to suppress plant disease such as phytophthora root rot.
Create a Winogradsky column
If you’ve enjoyed the microbial outdoors, why not create a “microbial pet” that you can bring inside? Meet the Winogradsky column. Named after its creator Sergei Winogradsky, these columns are a way to witness the amazingness of microbes that live off of mud, water, egg yolk, and other nutrients added to form an enclosed ecosystem within a glass jar. Here, the many environmental gradients, or areas with different living conditions allow different types of microbes to thrive. The bottom of the column contains anaerobic sediments, where Desulfovibrios and Clostridium grow. Above that, you have anaerobic waters where purple non-sulfur bacteria thrive, and beyond that is the aerobic water layer, full of Cyanobacteria.
Over the course of months, you can watch the changing growth patterns right from your home as different types of microbes wax and wane.
I hope this article helps you enjoy the microbes all around you. How else are you finding microbes in the great microbial outdoors?
Further reading:
What is a Lichen? The British Lichen Society
A window into the microbial world: the Winogradsky column. Joyful Microbes. 2020.
Compost Microorganisms. Cornell Composting
