An experiment was conducted to examine the efficiency of plant growth promoting rhizobacteria (PGPR) encapsulated in sodium alginate (SA) with either oak biochar (OK-BC) or sawdust biochar (SD-BC) at concentrations of 0. 2.5 and 5% on the growth of Zea mays. The PGPR strain SK1, isolated from the rhizosphere of Rhizophora mucronata, exhibited the potential to produce indole-3-acetic acid, siderophores, and solubilize phosphate. Based on 16S rDNA sequencing, strain SK1 was determined to be a member of the genus Bacillus. Characterization of the encapsulated beads revealed that the SA+SD-BC5%+SK1 formulation showed superior encapsulation efficiency, moisture retention, water absorption potential, and gradual release of SK1 cells compared to other treatments. Furthermore, the survivability of strain SK1 was remarkably increased in the SA+SD-BC5%+SK1 beads, maintaining viability after 80 days of storage even at room temperature. In pot experiments, Z. mays treated with SA+SD-BC5%+SK1 beads showed the greatest improvement in shoot length, root length, fresh weight, and dry weight relative to other treatments. Additionally, SA+SD-BC5%+SK1 beads improved the colonization of SK1 in the rhizosphere of Z. mays, which likely contributed to enhanced plant growth. In conclusion, the SA+SD-BC5%+SK1 formulation provided better survival and activity of PGPR compared to SA+SK1 beads alone, making it a promising and more effective carrier system for delivering beneficial microbes to the plant rhizosphere and thereby promoting plant growth.
| [1] | Mirzabaev, A., Kerr, R.B., Hasegawa, T., Pradhan, P., Wreford, A., von der Pahlen, M.C.T., and Gurney-Smith, H., “Severe climate change risks to food security and nutrition”, Climate Risk Management, vol. 39, p.100473, 2023.View Article |
| [2] | Khoso, M.A., Wagan, S., Alam, I., Hussain, A., Ali, Q., Saha, S., Poudel, T.R., Manghwar, H., and Liu, F., “Impact of plant growth-promoting rhizobacteria (PGPR) on plant nutrition and root characteristics: Current perspective”, Plant Stress, vol. 11, p.100341, 2024.View Article |
| [3] | Shah, A., Nazari, M., Antar, M., Msimbira, L.A., Naamala, J., Lyu, D., Rabileh, M., Zajonc, J., and Smith, D.L., “PGPR in agriculture: A sustainable approach to increasing climate change resilience”, Frontiers in Sustainable Food Systems, vol. 5, p.667546, 2021.View Article |
| [4] | Mushtaq, N., Iqbal, A., Batool, S., Janiad, S., Ahmed, M., Al-Asmari, F., Rahim, M.A., Ramadan, M.F., and Zongo, E., “Alginate beads encapsulated auxin-producing PGPR as a biofertilizer promotes Triticum aestivum growth”, ACS omega, vol. 10(5), pp.4303-4314, 2025.View Article PubMed |
| [5] | Najim, A.A., Radeef, A.Y., al‐Doori, I., and Jabbar, Z.H., “Immobilization: the promising technique to protect and increase the efficiency of microorganisms to remove contaminants”, Journal of Chemical Technology and Biotechnology, vol. 99(8), pp.1707-1733, 2024.View Article |
| [6] | Afshar, M., and Mofatteh, S., “Biochar for a sustainable future: Environmentally friendly production and diverse applications”, Results in Engineering, vol. 23, p.102433, 2024.View Article |
| [7] | Bolan, S., Sharma, S., Mukherjee, S., Kumar, M., Rao, C.S., Nataraj, K.C., Singh, G., Vinu, A., Bhowmik, A., Sharma, H., and El-Naggar, A., “Biochar modulating soil biological health: A review”, Science of the Total Environment, vol. 914, p.169585, 2024.View Article PubMed |
| [8] | Gorovtsov, A.V., Minkina, T.M., Mandzhieva, S.S., Perelomov, L.V., Soja, G., Zamulina, I.V., Rajput, V.D., Sushkova, S.N., Mohan, D., and Yao, J., “The mechanisms of biochar interactions with microorganisms in soil”, Environmental Geochemistry and Health, vol. 42(8), pp.2495-2518, 2020.View Article PubMed |
| [9] | Shabir, R., Li, Y., Rashti, M.R., Esfandbod, M., Megharaj, M., and Chen, C., “Alternative carrier materials for plant growth - promoting rhizobacteria: and perspectives”, Journal of Soils and Sediments, vol. 26(2), p.39, 2026.View Article |
| [10] | Balla, A., Silini, A., Cherif-Silini, H., Chenari Bouket, A., Alenezi, F.N., and Belbahri, L., “Recent advances in encapsulation techniques of plant growth-promoting microorganisms and their prospects in the sustainable agriculture”, Applied Sciences, vol. 12(18), p.9020, 2020.View Article |
| [11] | Hussain, T., Usman, S., Khan, A., Hussain, A., Aziz, A., and Ijaz, M., “Isolation and Characterization of Salt Tolerant Bacteria from Saline Areas of Khyber Pakhtunkhwa”, Journal of Clinical and Medical Research, vol. 4(4), pp.1-8, 2022. |
| [12] | Bric, J.M., Bostock, R.M., and Silverstone, S.E., “Rapid in situ assay for indoleacetic acid production by bacteria immobilized on a nitrocellulose membrane”, Applied and Environmental Microbiology, vol. 57(2), pp. 535–538, 1991.View Article PubMed |
| [13] | Schwyn, B.,and Neilands, J., “Universal chemical assay for the detection and determination of siderophores”, Analytical Biochemistry, vol. 160(1), pp. 47–56, 1987.View Article PubMed |
| [14] | Cappuccino, J.G., and Sherman, N., Microbiology: A Laboratory Manual, 9th ed., San Francisco: Pearson/ Benjamin Cummings, p. 507, 2005. |
| [15] | Sundaro Rao, W.V.B., and Sinha, M.K., “Phosphate dissolving micro-organisms in the soil and rhizosphere”, 1963. |
| [16] | Abd El-Rahman, A.F., and Shaheen, H.A., “Biological control of the brown rot of potato, Ralstonia solanacearum and effect of bacterization with antagonists on promotion of potato growth”, Egyptian Journal of Biological Pest Control, vol. 26(4), pp. 733–739, 2016. |
| [17] | Ma, Y., Rajkumar, M., Zhang, C., and Freitas, H., “Inoculation of Brassica oxyrrhina with plant growth promoting bacteria for the improvement of heavy metal phytoremediation under drought conditions”, Journal of hazardous materials, vol. 320, pp.36-44, 2016.View Article PubMed |
| [18] | Sahoo, S.S., Vijay, V.K., Chandra, R., and Kumar, H., “Production and characterization of biochar produced from slow pyrolysis of pigeon pea stalk and bamboo”, Cleaner Engineering and Technology, vol. 3, 100101, 2021.View Article |
| [19] | Wang,X., Tang, D., and Wang, W., “Characterization of Pseudomonas protegens SN15-2 microcapsule encapsulated with oxidized alginate and starch”, International journal of polymeric materials and polymeric biomaterials, vol. 70(10), pp.684-692, 2021.View Article |
| [20] | Lopes, A.R.D.O., Locatelli, G.O., Barbosa, R.D.M., Lobo Junior, M., Moura Mascarin, G., and Lamenha Luna Finkler, C., “Preparation, characterisation and cell viability of encapsulated Trichoderma asperellum in alginate beads”, Journal of Microencapsulation, vol. 37(3), pp.270-282, 2020.View Article PubMed |
| [21] | Dolatabad, H.K., “Multifactorial formulation for stable encapsulated plant growth promoting microorganisms”, Scientific Reports, 2025.View Article PubMed |
| [22] | Lopes, M.M., de Oliveira-Paiva, C.A., and Farinas, C.S., “Modification of pectin/starch-based beads with additives to improve Bacillus subtilis encapsulation for agricultural applications”, International Journal of Biological Macromolecules, vol. 246, p.125646, 2023.View Article PubMed |
| [23] | Hareem, M., Mahmood, S., Danish, S., Iqbal, R.K., Alarfaj, A.A., and Alharbi, S.A., “Influence of indole acetic acid, arginine and mango fruit waste biochar on nutrients, chlorophyll contents and antioxidants of Fenugreek in salt affected soil”, Scientific Reports, vol. 15 (1). 167, 2025.View Article PubMed |
| [24] | Truong, H.N., Fournier, C., Hichami, S., Dole, L., Leroy, F., Wendehenne, D., and Besson-Bard, A., “Apo-siderophores promote growth of iron-deficient Arabidopsis plants by mobilizing iron from roots to shoots and reducing oxidative stress in roots”, Plant Stress, vol. 12. 100488, 2024.View Article |
| [25] | Pattnaik, S., Mohapatra, B., and Gupta, A., “Plant growth-promoting microbe mediated uptake of essential nutrients (Fe, P, K) for crop stress management: Microbe–soil–plant continuum”, Frontiers in Agronomy, vol. 3. 689972, 2021.View Article |
| [26] | Malik, L., Sanaullah, M., Mahmood, F., Hussain, S., Siddique, M.H., Anwar, F., and Shahzad, T., “Unlocking the potential of co-applied biochar and plant growth-promoting rhizobacteria (PGPR) for sustainable agriculture under stress conditions”, Chemical and biological technologies in agriculture, vol. 9(1), p.58, 2022.View Article PubMed |
| [27] | Wang, B., Gao, B., Zimmerman, A.R., Zheng, Y., and Lyu, H., “Novel biochar-impregnated calcium alginate beads with improved water holding and nutrient retention properties”, Journal of environmental management, vol. 209, pp.105-111, 2018.View Article PubMed |
| [28] | Shaheen, A., and Turaib Ali Bukhari, S., “Potential of sawdust and corn cobs derived biochar to improve soil aggregate stability, water retention, and crop yield of degraded sandy loam soil”, Journal of Plant Nutrition, vol. 41(20), pp.2673-2682, 2018.View Article |
| [29] | Martínez-Cano, B., Mendoza-Meneses, C.J., García-Trejo, J.F., Macías-Bobadilla, G., Aguirre-Becerra, H., Soto-Zarazúa, G.M., and Feregrino-Pérez, A.A., “Review and perspectives of the use of alginate as a polymer matrix for microorganisms applied in agro-industry”, Molecules, Vol. 27(13), p.4248, 2022.View Article PubMed |
| [30] | Thies, J.E., and Rillig, M.C., “Characteristics of biochar: biological properties”, In Biochar for environmental management (pp.117-138). Routledge, 2012. |
| [31] | Lang, Z., Yan, S., and Zhu, Q., “Water retention and sustained release of magnesium-based biochar modified hydrogel composite materials”, Journal of Environmental Chemical Engineering, vol. 11(6), p.111380, 2023.View Article |
| [32] | Rojas-Padilla, J., De-Bashan, L.E., Parra-Cota, F.I., Rocha-Estrada, J., and De Los Santos-Villalobos, S., “Microencapsulation of Bacillus strains for improving wheat (Triticum turgidum Subsp.durum) growth and development”, Plants, vol. 11(21), p.2920, 2022.View Article PubMed |
| [33] | Das, S.K., and Ghosh, G.K., “Hydrogel-biochar composite for agricultural applications and controlled release fertilizer: A step towards pollution free environment”, Energy, vol. 242, p.122977, 2022.View Article |
| [34] | Bhattacharya, S., and Baidya, S., “Viability Preservation of Probiotic Bacteria Encapsulated in Pectin-Reinforced pH-Responsive Composite Alginate Hydrogel Matrix as the Symbiotic Delivery System”, Probiotics and Antimicrobial Proteins, pp.1-15, 2025.View Article PubMed |
| [35] | Shaaban, A., Se, S.M., Mitan, N.M.M., and Dimin, M.F.,“Characterization of biochar derived from rubber wood sawdust through slow pyrolysis on surface porosities and functional groups”, Procedia Engineering, vol. 68, pp.365-371, 2013.View Article |
| [36] | Wang, B., Wan, Y., Zheng, Y., Lee, X., Liu, T., Yu, Z., Huang, J., Ok, Y.S., Chen, J., and Gao, B.,“Alginate-based composites for environmental applications: a critical review”, Critical reviews in environmental science and technology, vol. 49(4), pp.318-356, 2019.View Article PubMed |
| [37] | Syaziana, N.S.A., Othman, N.M.I., Soraya, S.A., Ali, T.K.Z., and Musliyana, M., “Isolation and characterization of encapsulated plant growth-promoting Enterobacter sp. SA10 for enhancing chili growth”, Journal of King Saud University-Science, vol. 36(6), p.103197, 2024.View Article |
| [38] | Yang, L., Li, S., Ahmed, W., Jiang, T., Mei, F., Hu, X., Liu, W., Abbas, F.M., Xue, R., Peng, X., and Zhao, Z., “Exploring the relationship between biochar pore structure and microbial community composition in promoting tobacco growth”, Plants, vol. 13(21), p.2952, 2024.View Article PubMed |
| [39] | Laghari, M., Hu, Z., Mirjat, M.S., Xiao, B., Tagar, A.A., and Hu, M., “Fast pyrolysis biochar from sawdust improves the quality of desert soils and enhances plant growth”, Journal of the Science of Food and Agriculture, vol. 96(1), pp.199-206, 2016.View Article PubMed |
| [40] | Egamberdieva, D., Ma, H., Reckling, M., Omari, R.A., Wirth, S. and Bellingrath-Kimura, S.D., “Interactive effects of biochar, nitrogen, and phosphorous on the symbiotic performance, growth, and nutrient uptake of soybean (Glycine max L.)”, Agronomy, vol. 12(1), p.27, 2012.View Article |
| [41] | Hasan, A., Tabassum, B., Hashim, M., and Khan, N., “Role of plant growth promoting rhizobacteria (PGPR) as a plant growth enhancer for sustainable agriculture: A review”, Bacteria, vol. 3(2), pp.59-75, 2024.View Article |
| [42] | Jin, X., Bai, Y., Khashi u Rahman, M., Kang, X., Pan, K., Wu, F., Pommier, T., Zhou, X., and Wei, Z., “Biochar stimulates tomato roots to recruit a bacterial assemblage contributing to disease resistance against Fusarium wilt”, Imeta, vol. 1(3), p. e37, 2022.View Article PubMed |
| [43] | Jiang, Z., Li, Q., Peng, F., and Yu, J., “Biochar Loaded with a Bacterial Strain N33 Facilitates Pecan Seedling Growth and Shapes Rhizosphere Microbial Community”,Plants, vol.13(9), p.1226, 2024.View Article PubMed |
