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Microbes, metabolites and plant health

February 19, 2021
Microbial metabolites image

Microbial communities and their products play a significant role in plant health, productivity and vigor.

You may have heard that there are over a billion microbes in every gram of soil. That means that there are more microbes in one spoonful of soil than there are people in the world. An entire world in one small spoonful. 

What are microbes?

When you think of a microbe, you probably think of your high school biology class or the last time you had food poisoning, but they have a hand in so much more. Microbes are microscopic organisms that are all around us. They can be found in soil, water, air, and even in places that would be inhospitable, such as volcanic areas. 

In agriculture, microbes are involved in various plant processes and form symbiotic relationships with the plants around them. Microbial communities and their products play a significant role in plant health, productivity and vigor. Microbes help plants by doing things such as playing a role in breaking down organic residue, neutralizing potentially toxic compounds in soils, enhancing root growth, improving plant metabolism, increasing a plant’s access to nutrients, providing some disease suppression properties, and not only increasing the plant’s defense mechanisms against stressors but boosting the plant’s resistance to environmental changes and extremes. On the other hand, soils that have less of the microbial presence that plants rely on will also have decreased soil fertility, less organic matter and little organic activity, resulting in a crop that will not reach its potential for growth and development.

Microbes are able to provide such services to plants through the different metabolites that they produce during their life cycle. During their lifetimes, microbes — such as nitrogen-fixing bacteria — extract water and minerals from the soil. Once they die, they are broken down by other organisms and microbes, and the minerals that had been taken in by those microbes then become available to plants, combined with both organic and amino acids. 

What are metabolites?

Metabolites are molecular compounds that result from the life cycle of microorganisms. Metabolites play a role not only in agriculture and crop management but in human health and many other industries as well. One of the most recognized metabolites is penicillin. Other antibiotics are also metabolites of various bacteria and other microorganisms. 

Metabolites produced from bacteria during the fermentation process have a wide range of uses in nature. They are not just a byproduct created during the growth and development of the microbe; they can also have beneficial properties — like plant nutrient availability and aiding in disease management — that promote symbiotic relationships.

There are two types of metabolites that are created by the microbes. First, primary metabolites are those that are essential for the plant’s growth and development. 

Primary metabolites

  • Amino acids: The building blocks of protein molecules
  • Enzymes: Developed from the microorganisms themselves, they act as catalysts for various reactions without losing their own properties and characteristics
  • Vitamins: Essential micronutrients required by plants and animals to function
  • Organic acids and alcohols: These products of primary metabolism are predominantly used in industries outside of agriculture and range in their uses, from flavorings to fermentation, as well as many others

Secondary metabolites are more geared toward helping a plant respond to stressors, such as drought, salinity and pest pressure, and inducing the plant’s resistance to both biotic and abiotic stressors. Metabolites have also been found to be linked to the nutrient quality and availability of crops. 

Secondary metabolite properties

  • Pest management: Some secondary metabolites have biopesticide properties that target specific pests and weeds while decreasing environmental risks
  • Plant growth regulation: These metabolites act on differentiating plant cells and promoting or inhibiting plant growth as needed
  • Induced resistance: Secondary metabolites push the plant to form a response mechanism to stressors so those stressors have a diluted effect on plant growth, vigor and productivity

What are some of the beneficial microbes found in soil, and what do their metabolites do?

There are a multitude of microbial species that can help plant growth and productivity, most of which are still unknown. Some examples of the beneficial bacteria and fungi that have already been discovered include:

  • Bacillus subtilis: With more than 200,000 identified strains, this microbe family casts a wide net to fight against pathogens such as Fusarium, Pythium, Rhizoctonia and others. 
  • Bacillus licheniformis: This bacterium is excellent in its ability to break down especially tough proteins in plant residues, and research has found that it is also effective at nematode suppression and the synthesis of plant hormones.
  • Bacillus thuringiensis: Metabolites from these bacteria have insecticidal properties.
  • Lactobacillus plantarum: Various compounds, including lactic acid, create a hostile environment for competing microorganisms.
  • Trichoderma harzianum: This fungus builds a mutually beneficial relationship with a plant’s roots and can help protect against pathogens such as Pythium and Fusarium.
  • Trichoderma longibrachiatum: Research has found that not only does this fungal strain act as an antagonist against nematodes and other disease-causing fungi, but it may also have a positive influence on plant nutrient uptake and the production of plant hormones.
  • Aspergillus spp.: Strains of this mold have been known to produce enzymes that break down plant fibers, which, in turn, improves the soil structure and amount of organic matter and helps release energy and nutrients the plant can use for improved performance and productivity.

How is Alltech Crop Science harnessing the power of these microbes and metabolites?

The Alltech Crop Science mission is to provide unique, reliable and sustainable biological solutions to combat everyday agronomic challenges that occur in the soil, in the environment and in the plant. Alltech Crop Science’s expertise in fermentation technology and research-backed initiatives go hand in hand to create solutions that build on the characteristics of the microbes and their metabolites, as well as taking into account the relationship between plants and their environment.

“What sets Alltech Crop Science apart is our technology,” said Dr. Steven Borst, general manager of Alltech Crop Science. “Particularly, it is our ability to utilize fermentation media and metabolites to our advantage, and having an understanding of how to incorporate these technologies into management strategies.” 

Beginning in the soil rhizosphere, microbial diversity is constantly in a state of change, depending on variables such as soil characteristics and plant developmental stages. In turn, the types of metabolites that are being produced change as well. Being able to manage the changes and deficiencies caused by the changing conditions that influence metabolite production and sources is key to maintaining plant health. 

Many products on the market today tout the use of live microbials. Their claim is that the introduction of these live microbes will aid in soil and plant improvement and development. However, researchers have found that some products claiming to include live microbials sometimes have difficulties meeting their guarantees. 

“Microbes are notoriously difficult to keep alive, and even small changes in temperature, light and moisture levels can kill them during transport and storage,” said Borst. “When the grower uses the product, the live microbials that have survived face other dangers from other chemical applications and even other microbial products.”

In using metabolites instead of live microbes, Alltech Crop Science products provide the benefits of microbes without facing the same challenges. 

If this is the case, should I refrain from using products with live microbial cultures?

Not at all! Live microbial technologies have an important place in sustainable soil and crop management, and those that can maintain their guaranteed populations can be extremely beneficial for crops.

As Alltech Crop Science continues to develop its own microbial line — and applies stringent quality procedures and testing to ensure our live population guarantees — we will provide growers with options that bring a more natural approach into the management process and promote sustainable and balanced solutions.

Growers will see the same consistent results every time, whether they choose the Alltech Crop Science metabolite or live population products. Effectiveness is not diminished due to transport times or temperature differences between regions. The compatibility of Alltech Crop Science products with commonly used fertilizers, herbicides, fungicides and other products used on-farm also make them a reliable recommendation that meet their guarantees as well as grower expectations.


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