Know your Garden Microbes : Nostoc

 

Know your Garden Microbes : Nostoc 

As gardeners, we often focus on the macro aspects of our garden such as the plants, trees, and shrubs. But, what about the tiny microbes that play a vital role in the health of our gardens? Today, we are going to focus on a particular type of bacteria that is often overlooked: Nostoc.

What is Nostoc?

Nostoc is  a jelly-like microorganism commonly found growing on soggy lawns. While the discovery of the creature might be frightening for some gardeners, it poses no threat to plants or animals in the environment. Because the Nostoc grows in places where grass does not, it is likely to fill in any gaps left by the grass. Evidence of an imbalance in the ratio of fungus to bacteria can be easily identified. 

Figure 1: Nostoc Growing in the Garden.

It was once believed that these strange-looking masses of matter came from the dust of shooting stars, which gave rise to the nicknames star jelly, star shot, and star slime because of their outlandish appearance. Nostoc is also known as witch's butter or witch's jelly, which are both names that are derived from more apparent causes.

In addition to not being an extraterrestrial lifeform, Nostoc is just a cyanobacterium. Cyanobacteria are similar to bacteria in that they are tiny, single-celled creatures that lack a nucleus. However, unlike bacteria, cyanobacteria have a nucleus. Filaments are formed by Nostoc cyanobacteria, which are single-celled threadlike structures. These filaments frequently group together to create colonies that are large enough to be visible with the naked eye and are kept together by a jelly-like coating. Because cyanobacteria produce their food (carbohydrates) through photosynthesis, they differ from bacteria in that bacteria must obtain carbon and energy from outside sources, whereas bacteria must obtain these nutrients from within the environment. Cyanobacteria, like plants, produce chlorophyll, which is a green pigment that helps them capture sunlight. Cyanobacteria also generate a blue pigment known as phycocyanin, which is capable of absorbing sunlight in low-light situations and converting it to energy. The blue pigment phycocyanin is responsible for the origin of the term cyanobacteria, which literally translates as "blue-green" bacteria. 

Nostoc is believed to be one of the world's oldest creatures, having been on the planet for more than 3.5 billion years, according to fossil records. There are approximately 200 species of Nostoc, which colonise a wide range of habitats, including some of the most hostile locations on the face of the planet. There are species that live in both saltwater and freshwater, as well as species that live on land. This species generates a protective covering that helps it to survive under harsh situations such as drought and flooding, as well a high and low temperature range, without dying. Some Nostoc species have the ability to resist repeated freezing and thawing cycles, allowing them to survive in both the Arctic and Antarctic.

 Nostoc not only accomplishes photosynthesis, but it also engages in another unusual function that is commonly associated with leguminous plants: stomatogenesis. Using nitrogen gas from the environment, Nostoc is able to ‘fix' that form of nitrogen that can be utilised by plants. It is referred to as Nitrogen fixation. Nitrogen is utilised by all organisms in the production of amino acids, proteins, and other essential building blocks for life. While the earth's atmosphere is approximately 79% nitrogen gas, the gas form (N2) is ineffective for the majority of living organisms. To begin, nitrogen must be converted to ammonia (NH3). While legumes fix nitrogen in conjunction with rhizobia bacteria in the soil, Nostoc colonies generate specialised nitrogen-fixing cells called heterocysts. Heterocysts are bigger non-photosynthetic cyanobacteria cells. Rather than that, they fix nitrogen from the air and supply it to the other cyanobacteria cells. Meanwhile, the photosynthesizing cyanobacteria cells give carbohydrates to the heterocysts. Overall, Nostoc supplies far less nitrogen to the surrounding ecosystem than legumes, which contribute between twenty-five to several hundred pounds per year. While this small amount of nitrogen is insignificant for most cultivated crops, it is sufficient for a natural ecosystem. 

Research shows that  rice is one such crop that benefits from Nostoc's nitrogen fixation process. Nostoc is frequently prevalent in rice paddy production due to its capacity to survive in highly wet environments. You would be somewhat shocked to see such an organism in your garden , But such  cyanobacteria were almost certainly present all along in the form of a black, shrivelled crust, waiting for sufficient moisture to revert to their jelly-like consistency. Nostoc is non-toxic to grass and landscaping plants. Rather than that, the organism simply fills in spaces where grass or other plants cannot grow, such as areas with compacted soil, excessive moisture, or elevated soil phosphorus levels. One problem is there with it . It can build on damp concrete or gravel walkways, posing a slipping hazard if not treated properly.

While we may not like it growing in our lawns or on our sidewalks, consider the several redeeming qualities of Nostoc. Numerous Nostoc species have been used as food and medicine for millennia, and their medicinal characteristics, including antibacterial metabolites, cholesterol management, and the prevention of some malignancies, have been investigated more recently. Additionally, they have the potential to be used to create biofuels. They are capable of fixing nitrogen from the air and have pigments that enable them to photosynthesise using the sun's energy. According to the latest theories in evolutionary biology , it is believed that plants' chloroplasts are actually cyanobacteria that entered plant cells to have endosymbiosis. The plant and the bacteria become useful for each other and they live together forever. These bacteria also help in handling chemicals that absorb ultraviolet light, allowing them to resist extremely high levels of UV radiation. There are many  species that are suited to both water and land that can survive high temperatures, such as those found in pools of water near active volcanoes or in the Arctic. Cyanobacteria were very certainly the first creatures on the planet to release oxygen into the atmosphere, triggering the evolution of higher plant and animal species.

 

What are the benefits of Nostoc?

Although Nostoc is often considered a nuisance, it actually has many benefits for our gardens. One of the main benefits of Nostoc is that it is a natural fertilizer. It is able to fix atmospheric nitrogen into a form that can be easily absorbed by plants. This means that it helps to improve the health and growth of our plants without the need for synthetic fertilisers.

In addition to its fertilisation properties, Nostoc also has a symbiotic relationship with certain plants such as ferns, cycads, and Gunnera. This means that it forms a mutually beneficial relationship with these plants where both parties benefit from the interaction.

How to encourage Nostoc in your garden

If you want to encourage Nostoc in your garden, there are a few things you can do. First, make sure that your garden has plenty of moisture. Nostoc thrives in moist environments, so if your garden is dry, it may not be able to survive.

You can also try adding organic matter to your soil. This will provide the nutrients that Nostoc needs to thrive. Additionally, avoid using synthetic fertilisers and pesticides as these can harm Nostoc and other beneficial microbes in your soil.

Conclusion

In conclusion, Nostoc may be a tiny microbe, but it plays a significant role in the health of our gardens. By understanding the benefits of Nostoc and how to encourage its growth, we can create a healthier and more vibrant garden.

So, the next time you see blue-green algae in your garden, don't be so quick to remove it. Instead, take a moment to appreciate the benefits it provides and the role it plays in your garden ecosystem.