EPS Activation and Hydro-Lock Technology Is Increasing Soybean Nitrogen Fixation

By Jonathan Etherington and Nadine Loubser, MBFi

Microbial Biological Fertilizers International (MBFi) Group was founded in 2003 in South Africa. We have invested significantly into research and development and manufacturing capacity, to bring new high-quality technology in Rhizobium, Biological and Green Chemistry, Adjuvants and Bio-stimulant products to the global agricultural market. 

MBFi has three state-of-the-art plants, with two based in South Africa and one in the USA. The first two biological plants are based in Delmas, South Africa, with both solid state and liquid fermentation units. Our new and recent addition, St Joseph, Missouri accelerates our manufacturing capabilities to advanced delivery of biological products to more growers globally.  MBFi now has the combined capacity of up to 150 tons of solid state and 2.25 million liters of liquid fermentation which will set the standard for the latest biological production facilities. Further to biological product portfolios we have our world class specialty chemistry plants with a manufacturing capacity of more than 6000 tons in total - 2500 tons of powder formulations in SP, WP, WDG and 3500 tons of liquid formulation in SL, EC, ME, EW, SC.

Figure 1: MBFi, South Africa

We currently have registrations and are actively selling our products in 9 countries - USA, South Africa, Namibia, Botswana, Zambia, Egypt, Argentina, Chile, and Bolivia. We have submitted further registrations in Brazil, Argentina, and several other Latin American countries, which should be ready before the 2023 summer growing season for the Southern Hemisphere. MBFi Group’s production capacity and new technology gives us the ability to deliver high quality and high volumes of inoculants to the global agricultural industry. 

Our goal is to be a leader in science and a partner in growth with the global agricultural market. We are looking to significantly grow our pipeline globally. We currently have 379 registrations and 147 trademarks around the world. We have planted over 30 000 test plots on row crops to prove our technology and gain critical data for our growers and distributors regarding our products. On horticultural and tree crops we have conducted more than 1000 trials over the past seven years in various climatic conditions to prove product effectiveness.    

Figure 2: St. Joseph, Missouri, USA. June 2023, we had our first distributors visit the facility.

Figure 3: MBFi group started in South Africa in 2003, we now have offices in 5 countries – South Africa, USA, Brazil, Argentina and Chile.

Legumes are important sources of protein for humans and animals all over the world. To produce this large volume of protein these legumes require large amounts of Nitrogen. Atmospheric nitrogen (N₂) is present in large amounts; however, it is in an unusable form for the plant. Legumes, such as soybeans, can form a mutualistic relationship with a bacteria named Bradyrhizobium. A mutualistic relationship means that both the plant and the bacteria benefit from this relationship as the plant obtains nitrogen from the bacteria and the bacteria obtains sugars (food source) and shelter from the plant. Once the mutualistic relationship is formed, the bacteria can fix atmospheric nitrogen to ammonium which is in an available form for the plant to use. MBFi has developed a range of inoculants that contain these beneficial bacteria (Table 1). These inoculants can be applied to the soil or to seed for the beneficial relationship between the bacteria and the legume to form. 

Table 1: The two available products in the MBFi range include Induct and Induct Pro

The product containing the beneficial bacteria should be of high quality. There are a few main criteria to which these products should comply in order to qualify as high-quality products. 

• The bacteria (Bradyrhizobium) should be present in the product in high concentrations and should be free of any contaminants as it affects their functioning. 

• Long stable shelf-life of the product
  

• Accelerated and effective nodulation of the legume plant
  

• Packed into quality packaging to allow the bacteria to remain metabolically active 
  

At MBFi, we meet all of the above criteria to ensure that we sell products of high quality.  MBFi has developed, through many years of testing and trialing,  a very unique technolgy in our rhizobium products by the name of EPS activation technology. Exopolysaccharides (EPS) are extracellular polymers that are weakly associated with the rhizobia cell surface and abundantly released into the surrounding environment (Figure 4). In B. japonicum EPS is mainly composed of glucose, mannose, galacturonic acid, and galactose in a 2:1:1:1 molar ratio with a varying portion of galactose and 4-O-methyl galactose. These extracellular polymers perform numerous functions in the soil and provide the bacteria with an adaptive environmental advantage to secure on-seed and in-soil viability. EPS activation technology ensures that the bacteria are protected from unfavorable conditions on the harsh seed coat and soil conditions. 

Figure 4: Visualization of EPS that formed over B. japonicum cells using Scanning Electron Microscopy

There are a few advantages of EPS activation technology that contribute to the uniqueness of the product. EPS protects bacteria from various biotic and abiotic stresses by forming a protective barrier over cells (Figure 5).  Not only does this layer protect the bacteria, but it can also allow the accumulation of carbon sources and other nutrients that nourishes the bacteria and allow them to survive. EPS also contributes to the effective movement of the bacteria toward the roots of soybean plants by means of swarming. All the above-mentioned benefits are to improve the survival and movement of the bacteria, but EPS production also allows for phytoalexin production and increases plant defenses. Lastly, EPS allows for the successful interaction between the plant and the bacteria to establish a mutualistic relationship. 

Figure 5: Scanning Electron Microscopy indicating the EPS formed between cells (EPS highlighted in blue). 

We have found that biological nitrogen fixation (BNF) is affected by various stressors that affect the survival of rhizobia on the seed. Stressors cause a decrease in the viability and fitness of Bradyrhizobium spp. on seeds and in return affect symbiosis between the plant root and bacteria. Therefore, research and innovative strategies were employed to develop Bio-Shield XT to help protect cells from various stressors in their environment to prevent desiccation together with the use of the inoculant containing the EPS activation technology. The treatment of seed with Bio-Shield XT allows BNF to be maximized and crop yields can be increased. 

The key factors or stressors that have been shown to affect rhizobia survival include high seed storage and planting temperatures, poor adhesion of rhizobia to seed, toxic components that are secreted by the seed, dehydration of microorganisms when placed on seed or when treated with seed-applied technologies like film coatings, various powder or salts (micronutrients)  that accelerate dehydration, and lastly various chemical or biological seed care products including fungicides and insecticides. 

These adverse effects which limit Bradyrhizobium survival, may be ameliorated by using Bio-Shield XT in conjunction with MBFi’s biological inoculants Induct/Induct Pro. Bio-Shield XT function by limiting heat transfer from the environment to the microorganisms due to the low thermal conductivity potential and slowing the drying processes due to their high-water activity. These products contain ″hydrocolloids″ which aid with slowing the dehydration progression and preventing desiccation. The term ″hydrocolloid″ is derived from the Greek words hydro meaning ″water″ and kola meaning ″glue″. Hydrocolloids are hydrophilic (water-loving), high-molecular-weight molecules that generally contain several hydroxyl groups and are polyelectrolytes (Figure 6).  These compounds can also be used to control the functional properties (e.g. solubility, gelling, water binding, adhesion, film formation, or encapsulation) of aqueous solutions.  The presence of hydroxyl (-OH) groups on the hydrocolloid structure increase its affinity for water molecules.  Moreover, gel formation involves the cross-linking of the polymer chains to form a three-dimensional network that immobilizes water within it.

Figure 6: Illustration showing the affinity of hydrocolloid molecules to water. 

Other benefits of treating seed with Bio-Shield XT are that it aids in protecting cells against toxic seed coat factors by binding or inactivating it, it is easy to apply to seed, and these products contain red color pigments which allow identification of treated seed. 

All the benefits of using Bio-Shield XT allow for a pre-treatment window (Graph 1). As seen in Graph 1, there is a definitive difference in rhizobia survival numbers on seed due to the application of Bio-Shield XT just after treatment, and up to 21 days after treatment. 

Graph 1: In the graph above there are big differences between seeds that were treated with just the inoculant (left) and seeds treated with the inoculant and the extender (Bio-Shield XT) (right). Survival at the initial time of testing was higher when Bio-Shield XT was included in the treatment. These treatments were plated just after treatment (T0), after 7 days (T7), after 14 days (T14), and after 21 days (T21). 

By using Induct, Induct Pro Soybean together with Bio-Shield XT higher on-seed survival was seen and improved yield outputs were also observed. These products protect the rhizobia from harsh environmental conditions and ensure that their survival is improved in the field. These products can be used together to ensure that effective plant-bacteria relationships can exist to ensure optimal nitrogen fixation in soybeans. 

This article was initially published in AgroPages' '2023 Seed Treatment Special' magazine.

If you would like to share your company's story. Please contact Christina Xie at christina@agropages.com

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