Plant Growth Promoting Bacteria, or PGPB, are a major factor in determining plant health, plant productivity and overall soil fertility.

What are PGPB?

Plant growth promoting bacteria, present in the rhizosphere, are beneficial soil bacteria that enhance plant growth and reduce the abiotic stresses through a variety of mechanisms.

Since these beneficial bacteria are found in the rhizosphere, you will sometimes see the term PGPR, plant growth promoting rhizobacteria, used.

Several plant microbe interactions are generally classified as PGPB including:PGPB Plant Growth Promoting Bacteria

  • Phosphate solubilization
  • Biological nitrogen fixation
  • The production of phytohormones
  • ACC deaminase activity
  • The production of siderophores

Benefits of PGPB’s

There are several specific benefits to  the plant of plant growth promoting bacteria, including; increased agronomic activity, reduced overall production costs, and reduced environmental pollution.

Increased agronomic activity is the goal of every farmer, both commercial and home gardener. The use of PGBR increases root size and root strength in plants. In turn, these healthier roots help produce stronger, more productive plants.

The reduction in environmental pollution is achieved because less traditional fertilizers (N,P,K) are generally needed when sufficient amounts of plant growth promoting bacteria are added. This means that the fertilizers are used more efficiently. This efficient usage reduces costs and fertilizer runoff issues. Less use of N,P,K, means less fertilizers wash away. Since fertilizer runoff is a major environmental issue, use of PGPB reduces this problem.

For beneficial bacteria to be effective, several factors must be considered:

  • Overall soil condition, including soil pH, water, minerals, soil porosity
  • Extent of bacterial colonization of the root zone
  • Amount and types of plant exudates

The Future of Beneficial Microbes

Plant growth promoting bacteria have only recently become of interest to scientists and farmers. Over the next decade, I fully expect much more research will be done in this promising area.It is worth noting that by 2019, the agricultural microbials market is expected to reach 2.45 Billion USD.

Commercial Products

Custom Biological manufactures both Custom B5 and Custom N2. Both if these products are PGPB’s. Additionally, Biota Max™ contains both plant growth promoting bacteria and plant growth promoting fungi.

Custom Biologicals has been producing beneficial microorganisms for over 25 years. Distributor inquiries are always welcome. Contact CustomBio at (561)797-3008 or via email at

Here’s a list of all of our biological products.

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