The document discusses the roles of potassium (K) and zinc (Zn) solubilizing microorganisms in agricultural microbiology, detailing how certain bacteria can release potassium from minerals and enhance zinc availability in soils. Potassium is essential for ATP production and water uptake, while zinc is crucial for plant nutrition, with various microorganisms facilitating the solubilization of these elements through organic acid production and other mechanisms. The inclusion of these microorganisms in soil health management can improve nutrient availability and address deficiencies in crops.

1. AGM301. Agricultural microbiology (1+1)
Potash releasing &Zinc
solubilizing micro organisms

2. Pottasium In soil
• Pottasium is a chemical element with the symbol of K.
• Both N & P are constituents of soil organic matter, but not
pottasium.
• K is important to production of ATP.
• Water uptake by roots and its loss through stomate affected
by pottasium.

3. Potash releasing micro organisms
• Many bacteria such as Acidothiobacillus
ferrooxidans, Paenibacillus spp., Bacillus
mucilaginosus, B. edaphicus, and B.
circulans have capacity to release K.
• Aspergillus niger, Penicillium frequentans and
Cladosporium, were found to grow on muscovite,
biotite, orthoclase microclase and mica in vitro and
also releases K.

4. Mechanism Of K release
• It is generally believed that microorganisms
contribute to the release of K+ from K-bearing
minerals by several mechanisms.
• the major mechanism of K mineral solubilization
is by production the organic and inorganic
acids ,which are able to convert the insoluble K
(mica, muscovite, and biotite feldspar) to soluble
forms of K, easily taking up by the plant.

5. • The types of various organic acids such as oxalic acid,
tartaric acids, gluconic acid, 2-ketogluconic acid, citric
acid, malic acid, succinic acid, lactic acid, propionic
acid, glycolic acid, malonic acid, fumaric acid, etc.
which are effective in releasing K from K-bearing
minerals .
• These organic acids produced, enhance the
dissolution of potassium compounds by complexing
Ca2+ ions.

6. Aspergillus niger

7. Zn in soils
• Zinc is a chemical element with the symbol of Zn.
• The amount of zinc present in the soil depends on the parent
materials of that soil. Sandy and highly leached acid soils generally
have low plant available zinc. Mineral soils have low zinc
availablity.
• Plants take up zinc as the divalent ionic form (Zn2+) and chelated-zinc.

8. Zinc solubilizing micro organisms
• Zn solubilizing microrganisms are capable of solubilizing
insoluble zinc compounds through the production of
gluconic acid
• Inoculation of zinc solubilizing bacteria in soils inherently
along with cheaper insoluble zinc compounds, like ZnO or
ZnCO3, will be useful for enhancing Zn nutrition & alleviation
of Zn deficiency.
• Ex:Bacillus cereus, Bacillus sphaericus, Bacillus subtilis,
Gluconacetobacter diazotrophicus, Pseudomonas sp

9. Mechanism of Zn solubilization
• Zinc solubilizing microorganisms solubilize zinc through
various mechanisms, one of which is acidification.
• These microbes produce organic acids in soil which sequester
the zinc cations and decrease the pH of the nearby soil.
Moreoverr, the anions can also chelate zinc and enhance zinc
solubility .
• Other mechanisms possibly involved in zinc solubilization
include production of siderophores and proton, oxido-
reductive systems on cell membranes and chelates.

10. Bacillus cereus Pseudomonas sp

11. Advantages of Zn solubilizing M.O
• Enhance the grain Zn content
• Minimize the adverse effects of Zn deficiency.
• Increase the bioavailability of native and applied zinc
to the plants.
• . Overcome the malnutrition due to the Zn deficiency..

12. References
• www.ncbi.nlm.nih.gov.org
•www.sciencedirect.com
•Archana, D.S., Nandish, M.S., Savalagi,
V.P., Alagawadi, A.R. 2012. Screening
of potassium solubilizing bacteria
(KSB) for plant growth promotional
activity. BIOINFOLET-A Quarterly J.
Life Sci. 9, 627-630.