# Zinc-Solubilizing Bacteria: A Sustainable Approach for Enhancing Agricultural Productivity and Soil Health

Ramjas Meena, Ajeet Kumar, Sunita Kumari Meena, Sanjay Kumar Singh, Mohit Bairwa

► To cite this version:

Ramjas Meena, Ajeet Kumar, Sunita Kumari Meena, Sanjay Kumar Singh, Mohit Bairwa. Zinc-Solubilizing Bacteria: A Sustainable Approach for Enhancing Agricultural Productivity and Soil Health. New Era Agriculture Magazine, 2024, 3 (5), pp.90-95. [https://hal-04768233](https://hal-04768233)

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Submitted on 8 Nov 2024

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# Zinc-Solubilizing Bacteria: A Sustainable Approach for Enhancing Agricultural Productivity and Soil Health

Ramjas Meena*<fnref n="1" />, Ajeet Kumar<fnref n="2" />, Sunita Kumari Meena<fnref n="3" />, Sanjay Kumar Singh<fnref n="4" /> and Mohit Bairwa⁵

## Abstract: -

The ongoing increase in the global population necessitates greater food production. To meet this demand, farmers often use various agrochemicals, particularly fertilizers, in large quantities to boost crop yields per area and time. However, excessive and imbalanced fertilizer application can lead to significant environmental issues. While macro nutrients are typically supplied through high-analysis fertilizers, micronutrients like zinc (Zn) are often overlooked, even though they are vital for plant health. Zinc is an essential micronutrient required in small amounts for all living organisms, playing a critical role in the plant life cycle. Zinc deficiency in soil is quite common, highlighting the need for alternative, eco-friendly solutions. One such solution is the use of zinc-solubilizing bacteria (ZSB), which can enhance zinc availability to plants and promote sustainable agriculture. These beneficial bacteria not only improve zinc solubilization but also contribute to increased crop yields

**Key Words:** Zn Solubilizing Bacteria, soils, Soil health, Bio inoculants, Sustainable agriculture, Nutrient availability

## Introduction

Zinc is an essential micronutrient for crops, playing a vital role in their life cycle (Hirschi 2008). It directly and indirectly

influences plant growth, development, and yield. Zinc is crucial for various physiological, biochemical, and metabolic processes,

Ramjas Meena*<fnref n="1" />, Ajeet Kumar<fnref n="2" />, Sunita Kumari Meena<fnref n="3" />, Sanjay Kumar Singh<fnref n="4" /> and Mohit Bairwa<fnref n="1" />

Dr. Rajendra Prasad Central Agricultural University, Pusa (Samastipur)-848125, Bihar, India

<footnote n="1">¹ PG Research Scholar, Department of Soil Science, Faculty of Agriculture,</footnote>

<footnote n="2">²Assistant Professor-cum-Scientist (Sr. Scale), (Soil Science-Soil Microbiology) Department of microbiology, College of Basic Sciences and Humanities,</footnote>

<footnote n="3">³Assistant Professor, Department of Soil Science, Sugarcane Research Institute,</footnote>

<footnote n="4">⁴Assistant Professor, Department of Soil Science, TCA Dholi,</footnote>
including photosynthesis, carbohydrate and auxin metabolism, nodulation, and protein synthesis (Nitu et al., 2020). It is also linked to the RNA polymerase enzyme, which is necessary for protein production, and is required for the synthesis of growth hormones like IAA. A deficiency in zinc can cause physiological stress, leading to enzyme dysfunction and altered metabolic rates (Sinha et al., 2024). Unfortunately, zinc is often not readily available to plants; only 1-5% of the applied zinc is utilized, while the remaining 95% becomes insoluble. Common insoluble forms include zinc oxide (ZnO), zinc carbonate (ZnCO3), and zinc phosphate (Zn3(PO4)2). Additionally, the use of chemical fertilizers is costly and environmentally harmful, making crops more susceptible to diseases and decreasing long-term soil fertility (Kumar et al., 2023), which also negatively impacts soil microorganisms. The heavy application of fertilizers has contributed to water and soil pollution, posing risks to both plant and human health (Kumar et al., 2024a). Fortunately, certain bacteria can convert insoluble forms of zinc, such as ZnO, ZnCO3, and Zn3(PO4)2, into bioavailable forms (Kumar et al., 2024b). Notable zinc-solubilizing bacteria include Pseudomonas fluorescens, Pseudomonas aeruginosa, various Bacillus species, Gluconacetobacter diazotrophicus, Klebsiella species, Acinetobacter calcoaceticus, Bacillus aryabhattai, Pseudomonas taiwanensis, Acinetobacter species, and Serratia species, can effectively transform insoluble zinc compounds like zinc oxide

calcoaceticus, Bacillus cereus, B. aryabhattai, Pseudomonas taiwanensis, Acinetobacter species, and Serratia species.

## Role of zinc in plants

Zinc (Zn) plays a vital role in numerous physiological and metabolic functions. It is a key element in processes such as photosynthesis, carbohydrate and auxin metabolism, nodulation, and protein synthesis, it is also suitable for maintain soil health (Meena et al., 2024). Zinc is closely associated with the RNA polymerase enzyme, which is essential for protein synthesis, and is also necessary for the production of growth hormones like indole-3-acetic acid (IAA) (Kumar et al., 2024)

## Microorganisms for zinc solubilization

Zinc Solubilizing Bacteria (ZSB) play a crucial role in boosting agricultural productivity while ensuring environmental sustainability. These bacteria have the ability to convert insoluble forms of zinc into bioavailable forms that plants can easily absorb. Several bacteria, including Pseudomonas fluorescens, Pseudomonas aeruginosa, various Bacillus species, Gluconacetobacter diazotrophicus, Klebsiella species, Acinetobacter calcoaceticus, Bacillus cereus, B. aryabhattai, Pseudomonas taiwanensis, Acinetobacter species, and Serratia species, can effectively transform insoluble zinc compounds like zinc oxide

NEW ERA AGRICULTURE MAGAZINE
(ZnO), zinc carbonate (ZnCO₃), and zinc phosphate (Zn₃(PO₄)₂) into forms accessible to plants (Kumar *et al.*, 2019).

## Mechanism of zinc solubilization

The formation of insoluble zincate due to zinc fertilizer applications poses a significant threat to the plant-soil system. Zinc Solubilizing Bacteria (ZSB) offers a promising alternative by converting insoluble soil zinc into soluble forms. As these microbes grow, they produce organic acids that interact with the minerals in the soil, effectively binding to zinc cations and lowering the local soil pH. Anionic organic acids, such as gluconic and ketogluconate, can chelate zinc through their carboxyl and hydroxyl groups, enhancing its solubility and facilitating mineral uptake by plants. Various organic acids are generated depending on the source of inorganic zinc in vitro, including keto-D-glutarate, propionic acid, formic acid, lactic acid, gluconic acid, citric acid, succinic acid, malic acid, and oxalic acid. In addition to organic acid production, other mechanisms such as siderophore production, proton exchange through cell membranes, and the action of chelating ligands also contribute to zinc solubilization (Kumar and Paswan., 2014; Kumar and Paswan., 2015). For example, the ability of soil bacteria such as *Bacillus* and *Pseudomonas* to solubilize zinc has been linked to their production of organic acids like

formic, acetic, propionic, lactic, glycolic, fumaric, and succinic acids (Kumar *et al.*, 2014).

## Importance of zinc solubilizing biofertilizer in agriculture

There is zinc deficiency in the whole country because there are many reasons behind it such as:- Low adoption rate of Zinc Biofertilizers, Lack of awareness among farming community regarding Zinc Biofertilizers, Spurious materials available in the market for Zinc Biofertilizers, Shelf life of Zinc Biofertilizers, mainly using lignite as Carrier based Preparation (Less Shelf life/ Moisture contents/ Non-autoclaving of carrier materials), Ecological fitness of Bio-inoculants related to Zinc Biofertilizers, Need to enhanced shelf-life and effectiveness, and need to shifts towards Liquid based preparation, Maintenance of Viable cell count even at the time of expiry, Aseptic condition for packaging of Zinc Biofertilizer products, This initiative represents a holistic approach to greener, sustainable and more productive farming, benefiting farmers, consumers and the environment.

## Conclusion

Zinc-Solubilizing Bacteria (ZSB) play a vital role in addressing zinc deficiency in soils, which is crucial for improving crop yield and maintaining soil health. By converting insoluble forms of zinc into bioavailable
forms, ZSB offer a sustainable alternative to chemical fertilizers, which often pose environmental risks and are less efficient in zinc utilization. Despite the challenges such as low adoption rates, limited awareness, and issues with the shelf life of zinc biofertilizers, these bacteria represent a promising solution for eco-friendly and sustainable farming practices. Enhancing the shelf life of biofertilizers, raising awareness among farmers, and shifting towards more stable liquid-based formulations will be key to maximizing the benefits of ZSB. This approach not only supports greener agricultural practices but also improves long-term productivity, benefiting both farmers and the environment.

## References

1. Kumar, A., Dewangan, S., Lawate, P., Bahadur, I. and Prajapati, S., 2019. Zinc-solubilizing bacteria: a boon for sustainable agriculture. *Plant Growth Promoting Rhizobacteria for Sustainable Stress Management: Volume 1: Rhizobacteria in Abiotic Stress Management*, 139-155.

2. Kumar, Ajeet., Chattopadhyay, S. and Meena, S.K. (2023) Soil Fertility Assessment of Sugarcane Growing Villages in Samastipur District of Bihar. *Environment and Ecology*. 41 (2): 759-764, April-June 2023. Link: https://doc.article-environmentandecology.com/external/file/15vy05a767e7a4e17435695f722fc209e2248

3. Kumar, Ajeet., Meena, S.K., Sinha, S.K., Singh, A.K., Minnatullah, and Singh, S. K. (2024b) Isolation and biochemical characterization of endophytic bacterium *Gluconacetobacter diazotrophocus* from native sugarcane cultivar of middle gangetic plains of India. *Indian Journal of ecology*, 51(1): 104-112. DOI: https://doi.org/10.55362/IJE/2024/4202

4. Kumar, Ajeet., Singh, S.K., Meena, S.K., Sinha, S.K. and Rana L (2024a) Groundwater contamination with nitrate- and human health risk assessment of North East alluvial plains of Bihar. *International Journal of Environment and Climate Change*, 14(3), 17-31. https://doi.org/10.9734/ijecc/2024/v14i34016; https://hal.science/hal-04484961

5. Kumar, B., Sinha, S.K., Kumar, Ajeet., and Kumari, A. (2024). Exploring the Impact of Organic-Inorganic Coupling on Nutrient Use Efficiency and Cane Yield in Calcareous Soils of the Indo-Gangetic Plains of India. *Journal of

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6. Meena, S.K., Kumar, Ajeet., Meena, K.R., Sinha, S.K., Rana, L., Singh, A.K., Parewa, H.P. and. Meena, V.S (2024). Advanced and Emerging Techniques in Soil Health Management. Pages: 343-362; In: Bhatia, R.K., Walia, A. (eds) Advancements in Microbial Biotechnology for Soil Health. Microorganisms for Sustainability, vol 50. Springer, Singapore.
https://doi.org/10.1007/978-981-99-9482-3 15.

7. Nitu, R., Rajinder, K. and 10. Kumar, Ajeet and Paswan, D. (2014) Sukhminderjit, K., 2020. Zinc solubilizing bacteria to augment soil fertility-A comprehensive review. *Int. J. Agricult. Sci. Vet. Med, 8*. 38-44.

8. Sinha, S.K., Kumar, Ajeet., Kumari, A and Singh. A.K. (2024) The integrated effect of organic manure, biofertilizer and inorganic fertilizer on soil properties, yield and quality in sugarcane plant-ratoon system under calcareous soil of indo gangetic plains of india. Journal of Scientific Research and Reports (JSRR). 30(5): 193-206.

https://doi.org/10.9734/jsrr/2024/v30i5
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9. Kumar, Ajeet and Paswan, D. (2015) Response of pea (Pisum sativum L.) to Rhizobium inoculation and nitrogen application in soils of North East Alluvial plains of Bihar. *An Asian Journal of Soil Science* (An International Refereed Research Journal). **10 (2): 252-258** (December, 2015). https://hal.science/hal-04676715.

https://www.researchgate.net/publication/296685720ayoefnLtoRhiobiuminoculat ionand nitrogen application in soils of North East alluvial plains of Bi har

Response of biofertilizers on biomass partitioning pattern and yield of pea (Pisum sativum L.). *An Asian Journal of Soil Science* (An International Refereed Research Journal). **9 (2): 221-225** (December-2014).
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11. Kumar, Ajeet., Choudhary, C.S., Paswan, D., Kumar, B. and Arun, A. (2014) Sustainable Way for Enhancing Phosphorus Efficiency in Agricultural Soils through Phosphate Solubilizing Microbes – A *Review*. *An Asian*
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(2014).https://hal.science/hal-04676707

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