Garden & Greenhouse


Microbe Plant Interactions in Nature

Posted February 2nd, 2018 by Garden & Greenhouse in , ,

Microbe plant interactions are an ongoing, ever changing encounter. This is a microscopic, symbiotic relationship unseen by the naked eye. Here’s a great quote from Nature the international weekly journal of science.

Plant and microbe encounters can be friendly or hostile. Densely colonized soil contains beneficial mycorrhizal fungi and rhizobia, which associate with roots and provide plants with mineral nutrients and fixed nitrogen, respectively, in exchange for carbon. This article will discuss only the friendly interactions between microbes and plants along with bacteria and the microscopic fungi, Trichoderma.

Types of Microbe Plant Interactions

There are too many types of microbe plant friendly interactions to completely discuss here in one article, but we’ll talk about a few of the main ones.

    • Carbon root exudate by plants
    • Nitrogen fixation by bacteria
    • Phosphate solubilization by bacteria and fungi
    • Auxin and other growth hormone production by bacteria and fungi

Carbon Root Exudate

Plant exudate, or excrete carbon compounds into the soil. These compounds serve to attract a variety of microorganisms. The microorganisms need the carbon for cellular components and to reproduce.

Nitrogen Fixation

Nitrogen is needed by plants for both protein synthesis and for DNA and RNA synthesis. Atmospheric nitrogen is very abundant. The problem is atmospheric nitrogen is not available to plants. Many bacteria, including Paenibacillus, are capable of taking atmospheric Nitrogen and incorporating the Nitrogen into their cell. This process is called Nitrogen fixation. By use of this process, atmospheric nitrogen, otherwise unavailable to the plant, is now available. Nitrogen fixing bacteria are an integral part of the Nitrogen cycle.

Phosphate Solubilization

Phosphate is required by plant cells for both DNA synthesis and energy transport. The important chemicals ATP and ADP both require phosphate. Both bacteria and Trichoderma solubilize phosphate and make it available to the plant. The phosphate cycle, while not as well-known as the nitrogen or carbon cycles, is vital to the plants survival.

Auxin Production

Auxins are growth hormones that stimulate plant growth, particularly root growth. More auxins cause plants to have healthier, better developed root systems. Better root systems, of course, mean a healthier, more productive plant. Several bacterial species and Trichoderma fungi produce auxins and a myriad of other plant growth hormones.

Microbe plant interactions are diverse and complex. It is safe to say, that without beneficial soil microbes, plants would have difficulty growing to their full potential.

Bill Baugh is a product manager for Custom Biologicals, Inc. a manufacturer and distributor of innovative microbial products. You can visit their website at and he can be contacted at 561.797.3008 or

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