Nitrogen-fixing Potential of Bacillus Strains Isolated from Soils and Roots Across Different Levels of Anthropization in Côte d’Ivoire

N’DRI Ahou Roseline^{1, 2,} , ALUI Konan Alphonse³, KOKORA Aya Philomène^{1, 2}, ANGORATCHI Marius Ebaley Yves-Magloire^{1, 2}, ANGOUA Amanahan Mauricette Prisca², TOURE Kakoumani Lama Ruth^{1, 2}, COULIBALY Yele Fatoumata^{1, 2}, KARAMOKO Detto^{1, 2} and MOROH Jean-Luc Aboya^{1, 2}

¹Laboratory of Biotechnology and Agro-food Valorization (Labo BiVA), Faculty of Biological Sciences, Peleforo Gon Coulibaly University, Korhogo, Côte d’Ivoire

²Department of Biochemistry and Genetics, Faculty of Biological Sciences, Peleforo Gon Coulibaly University, Korhogo, Côte d’Ivoire

³Department of Geosciences, Faculty of Biological Sciences, Peleforo Gon Coulibaly University, Korhogo, Côte d’Ivoire

Cite this paper:
N’DRI Ahou Roseline, ALUI Konan Alphonse, KOKORA Aya Philomène, ANGORATCHI Marius Ebaley Yves-Magloire, ANGOUA Amanahan Mauricette Prisca, TOURE Kakoumani Lama Ruth, COULIBALY Yele Fatoumata, KARAMOKO Detto and MOROH Jean-Luc Aboya. Nitrogen-fixing Potential of Bacillus Strains Isolated from Soils and Roots Across Different Levels of Anthropization in Côte d’Ivoire. Journal of Applied & Environmental Microbiology. 2026; 14(1):1-8. doi: 10.12691/jaem-14-1-1

Abstract

In the context of declining soil fertility associated with agricultural intensification in Côte d’Ivoire, the use of plant growth promoting rhizobacteria (PGPR) represents a sustainable alternative to nitrogen-based inputs. This study assessed the atmospheric nitrogen-fixing potential of cultivable bacteria isolated from rhizospheric soils and roots (endophytes) collected along a gradient of anthropization. A total of sixty-five (65) samples were collected from anthropized areas (maize and cassava fields) and low-anthropized areas (Banco Forest, Haut Bandama Reserve, and Lataha). Following isolation on nutrient agar and Pseudomonas Agar, 234 isolates were purified (78.63% rhizospheric; 21.37% endophytic). Nitrogen-fixing capacity was screened in vitro using nitrogen-free peptone water, with colorimetric quantification of ammonia production. Cultivable bacterial densities were generally higher in soils than in roots and tended to increase in low-anthropized sites. Among the isolates, 96.15% produced ammonia, with 14 isolates showing high performance after 72 h of incubation. The concentrations produced by these bacteria ranged from 18.60 x 10^-3 to 11.05 x 10^-3 mg/ml. Three sporulating isolates were selected and identified using the API 50 CHB system as Bacillus cereus (88.6%), Bacillus coagulans (70.5%), and Brevibacillus laterosporus (83%). Ammonia assimilation increased linearly with bacterial abundance, and strain-specific efficiency differed significantly, with Brevibacillus laterosporus exhibiting the highest performance. These results highlight the potential of sporulating bacilli as promising biofertilizer candidates.

Keywords:
Plant growth–promoting rhizobacteria biological nitrogen fixation ammonia Bacillus anthropization gradient

This work is licensed under a Creative Commons Attribution 4.0 International License. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/

Figures

References:

[1]	PNIA2, "Programme National d’Investissement Agricole de deuxième génération 2018-2025", Programme National d’Investissement de deuxième génération, PNIA2 2018, 189.
[2]	ONU, "World Population Prospects 2024", Department of Economic and Social Affairs (DESA) Population Division, 2024, Decembre 2025, [online] Available: https:// population.un.org/ wpp/graphs?loc=384&type=Demographic%20Profiles&category=Line%20charts.
[3]	Zozoro G, "In Côte d'Ivoire a changing climate hits farmers and markets alike", 2025, 30 Janvier 2026, https:// news.mongabay.com/ 2025/ 05/ in-cote-divoire-a-changing-climate-hits-farmers-and-markets-alike/.
[4]	Kumar V and Kumar P, Pesticides in agriculture and environment: Impacts on human health, In: Contaminants in Agriculture and Environment: Health Risks and Remediation, Agro Environ Media; 2019, 76-95.
[5]	Garrigou A, Laurent C, Berthet A, Colosio C, Jas N, Daubas-Letorneux V, Filho J-M J, Jouzel J-N, Samuel O, Baldi I, Lebailly P, Galey L, Goutille F and Judon N, "Critical review of the role of PPE in the prevention of risks related to agricultural pesticide use ", Safety Science, 123, 104527, 2020.
[6]	Lida D S, Bourdeix R, Droh R, Elias M and Diarrassouba A, "Changement climatique et rapport aux innovations technologiues agricoles dans la culture de manioc chez les paysans de Grand-Bassam (Côte d'Ivoire) ", Revue Sociétés et Economies, 9, 5-22, 2016.
[7]	Kouadio K P, Yoboué K E, Touré N, Beugré C M, Aka K F, Kouakou K J and Yao-Kouamé A, "Effet des téguments de fèves de cacao sur la fertilité chimique d’un ferralsol et quelques paramètres de croissance du manioc, à Ahoué, Sud-Est Côte d’Ivoire", Journal of Applied Biosciences, 121, 12144-12156, 2018.
[8]	Lindstrom K and Mousavi S A, "Rhizobium and other N-fixing Symbioses", Encyclopedia of life sciences, 1, 1-14, 2010.
[9]	Aserse A A, Markosb D, Getachewb G, Yli-Hallac M and Lindströma K, "Rhizobial inoculation improves drought tolerance, biomass and grain yields of common bean (Phaseolus vulgaris L.) and soybean (Glycine max L.) at Halaba and Boricha in Southern Ethiopia ", Archives of Agronomy and Soil Science, 66, (4), 488-501, 2020.
[10]	Bouznad A, "Isolement et caractérisation des rhizobactéries libres et endophytes (Bacillus sp et Pseudomonas sp): Etude de leur pouvoir protecteur vis-à-vis de Fusarium oxysporum f. sp lycopersici et leur caractères liés à la promotion de la croissance des plantes", [Thése]: Doctorat en Sciences. Sciences Biologiques Option: Microbiologie appliquée, Universite Abdelhamid Benbadis, Algérie, 2016, 197.
[11]	Barakat I, Chtaina N, El Guilli M and Ezzahiri B, "Évaluation du potentiel antagoniste de quelques isolats de bactéries et de Trichoderma spp. dans le contrôle de Zymoseptoria tritici agent causal de la septoriose du blé", Revue Marocaine des Sciences Agronomiques Vétérinaires, 6, (3), 345-354, 2018.
[12]	Budi I S and Mariana M, "Effectiveness of Trichocompost and PGPR on Controlling Fusarium Disease of Brown Rice (Oryza Nivara) in Nursery", International Journal of Chemical and Life Sciences, 12, (3), 2469-2480, 2023.
[13]	Alavo B C T, Aboudou M, Didolanvi L and Fayalo D G, "Effets de la rhizobactérie Bacillus amyloliquefaciens FZB 42 sur la tolérance au stress hydrique et le rendement du cotonnier", International Journal Biological Chemical Sciences, 12, (3), 1437-1446, 2018.
[14]	Safriani S R, Fitri L and Ismail Y S, "Isolation of Potential Plant Growth Promoting Rhizobacteria (PGPR) from Cassava (Manihot esculenta) Rhizos-phere Soil", Journal of Biology and Biology Education, 12, (3), 459-468, 2020.
[15]	Adoko M Y, Sina H, Amogou O, Agbodjato N A, Noumavo P A, Aguégué R M, Assogbato S A, Adjovi N A, Dagbénonbakin G, Adjanohoun A and Baba-Moussa L, "Potentiel of Biostimulants Based on PGPR Rhizobacteria Native to Benin Soils on the Growth and Yield of Maize ( Zea mays L.) under Greenhouse Conditions", Open Journal of Soil Science, 11, (3), 177-196 2021.
[16]	García J E, Ruiz M, Maronichec G A, Creus C, Bridge M, Zawoznik M S and Groppa M D, "Inoculation with Azospirillum argentinense Az19 improves the yield of maize subjected to water deficit at key stages of plant development", Revista Argentina de Microbiología, 1-7, 2023.
[17]	Umba d M b J, Pululu B H, Mumba D A, Bamuene S D and Khasa D, "Conception d’un modèle entomo-agroforestier à légumineuses restauratrices de fertilité et nourricières de Cirina forda", Journal of Animal et Plant Sciences, 55, (1), 10043-10052, 2023.
[18]	Mahmud K, Makaju S, Ibrahim R and Missaou A, "Current Progress in Nitrogen Fixing Plants and Microbiome Research", plants, 9, (1), 1-17, 2020
[19]	Assemien E F L, "Impact de pratiques agricoles conventionnelles et innovantes sur la fertilité des sols et les acteurs microbiens impliqués dans la zone de savanes humides de Côte d’Ivoire", [Thèse]: Doctorat. Biologie et Biochimie Université de Lyon, France, 2018, 203.
[20]	Lisboa P H G, Andrade P H M d, Machado P C, Sousa C P d and Lacava P T, "Isolation and in vitro screening of plant growth[1]promoting rhizobacteria from Solanum lycocarpum St. Hil., an endemic plant of the Brazilian tropical savannah", African Journal of Microbiology Research, 15, (5), 253-261, 2021.
[21]	Fukuda T T H, Pereira C F, Melo W G P, Menegatti C, Andrade P H M, Groppo M, Lacava P T, Currie C R and Pupo M T, "Insights Into the Ecological Role of Pseudomonas spp. in an Ant-plant Symbiosis", Frontiers in Microbiology, 12, 621274, 2021.
[22]	Ouattara A, "Isolement et sélection de bactéries endophytes natives du cacaoyer (Theobroma cacao L.) efficientes dans le biocontrôle de Phytophthora spp., agent causal de la pourriture brune des cabosses", [Thèse ]: Doctorat. Agriculture et foresterie tropicale: Microbiologie des sols, Université Jean Lorougnon GUEDE, République de Côte D’ivoire, 2020, 232.
[23]	Forchetti G, Masciarelli O, Alemano S, Alvarez D and Abdala G, "Endophytic bacteria in sunflower (Helianthus annuus L.): isolation, characterization, and production of jasmonates and abscisic acid in culture medium", Applied Microbial and Cell Physiology, 76, 1145–1152, 2007.
[24]	Cappuccino J C and Sherman N, "Microbiology: A Laboratory Manual, third", Pub Co New York, 125-179, 1992.
[25]	Ehis-Eriakha C B, Ezeanya-Bakpa C C, Akemu S E and Yahaya S O, "Assessment of Indigenous Rhizospheric Soil Microbes from Zea mays and Manihot esculenta for Plant Growth Promoting (PGP) Traits", Archive of Science & Technology, 1, 88 - 97, 2020.
[26]	Kébé I B, Mpika J, N’guéssan K F, Hebbar P K, Samuels G S and Ake S, "Isolement et identification de microorganismes indigènes de cacaoyères en Côte d’Ivoire et mise en évidence de leurs effets antagonistes vis-à-vis de Phytophthora palmivora, agent de la pourriture brune des cabosses", Sciences & Nature, 6, (1), 71-82, 2009.
[27]	Hallmann J, Quadt-Hallmann A, Mahaffee W F and Kloepper J W, "Bacterial endophytes in agricultural crops", Canadian journal of microbiology, 43, 895-914, 1997.
[28]	Foster R C and Rovira A D, The ultrastructure of the rhizosphere of Trifolium subterraneum L. In: Microbial ecology Springer-Verlag berlin, 1978, 278-280.
[29]	Ranjard L, Dequiedt S, Prevost-Bouré N C, Thioulouse J, N P A S, Lelievre M, Maron P A, Morin F E R, Bispo A, Jolivet C, Arrouays D and Lemanceau P, "Turnover of soil bacterial diversity driven by wide-scale environmental heterogeneity", Nature communications, 4, 1434, 2013.
[30]	Finnegan S and Droser M L, "Relative and absolute abundance of trilobites and rhynchonelliform brachiopods across the Lower/ Middle Ordovician boundary, eastern Basin and Range", Paleobiology, 31, 480–502 2005.
[31]	Badri D V, Chaparro J M, Zhang R, Shen Q and Vivanco J M, "Application of natural blends of phytochemicals derived from the root exudates of Arabidopsis to the soil reveal that phenolic-related compounds predominantly modulate the soil microbiome", Journal of Biological Chemistry, 288, (7), 4502-4512, 2013.
[32]	Karimi B, Terrat S, Dequiedt S, Saby N P, Horrigue W, Lelièvre M and Cruaud C, "Biogeography of soil bacteria and archaea across France", Science advances, 4, (7), 1808, 2018.
[33]	Patel T S and Minocheherhomji F P, "Review: plant growth promoting rhizobacteria: blessing to agriculture", International Journal of Pure and Applied Bioscience, 6, (2), 481−492, 2018.
[34]	Nugroho A A, Agustiyani D, Sutisna E, Mulyani N, Dewi T K, Nditasari A, Antonius S and Purwaningsih D S, "The Potential of Rhizobacteria in Supporting the Growth of Cassava (Manihot esculenta Crantz) ", Berita Biologi, 22, (3), 247-260, 2023.
[35]	Rosenblueth M, Ormeño-Orrillo E, López-L ópez A, Rogel M A, Reyes-Hernández B J, Martínez-Romero J C, Reddy P and Martínez-Romero E, "Nitrogen Fixation in Cereals", Frontiers in Microbiology, 9, 1-9, 2018.
[36]	Srivastava N, Bhandari V and Bhatt A B, "PGPR Isolated from rhizospheric soil of Zanthoxylum armatum DC. in Garhwal Himalaya", International Journal of Herbal Medicine, 2, (1), 100-108, 2014.
[37]	Ahmad F, Ahmad I and Khan M S, "Screening of free-living rhizobacteria for their multiple plant growth promoting activities", Microbiological Research, 163, 173-181, 2008.
[38]	Fantinel V S, Muniz M F B, Poletto T, Dutra A F, Krahn J T, Favaretto R F and Sarzi J S, "In vitro biocontrol of Colletotrichum siamense using Trichoderma spp. and Bacillus thuringiensis var. kurstaki", Revista Ciência Agrícola, 16, (3), 43-50, 2018.
[39]	Abe A M K, Assanvo J B, Sanogo M and Koffi K M, "Caractérisation phénotypique de 52 souches des Bacillus isolées à partir de racines fraîches de manioc cultivées en Côte d’Ivoire", International Journal of Biological and Chemical Sciences, 12, (5), 2284-2293, 2018.
[40]	Swiatczak J, Kalwasinska A, Wojciechowska A and Brzezinska M S, "Physiological properties and genomic insights into the plant growth-promoting rhizobacterium Brevibacillus laterosporus K75 isolated from maize rhizosphere", Journal of the Science of Food and Agriculture, 13, (3), 1432-1441, 2022.
[41]	Radhakrishnan R, Hashem A and Abd_Allah E F, "Bacillus: A Biological Tool for Crop Improvement through Bio-Molecular Changes in Adverse Environments", Frontiers in Physiology, 8, 667: 661-617, 2017.
[42]	Wang X, Zhang J, Wang X, An J, You C, Zhou B and Hao Y, "The Growth-Promoting Mechanism of Brevibacillus laterosporus AMCC100017 on Apple Rootstock Malus robusta", Horticultural Plant Journal, 8, (1), 22-34, 2022.
[43]	Kulkova I, Dobrzynski J, Kowalczyk P, Beł˙zecki G and Kramkowski K, "Review: Plant Growth Promotion Using Bacillus cereus", International Journal of Molecular Sciences, 24, 1-18, 2023.
[44]	Chhetri S, Sherpa M T and Sharma L, "Characterization of plant growth promoting bacteria isolated from rhizosphere of tomato cultivated in Sikkim Himalaya and their potential use as biofertilizer", Scientific Reports, 15, 11558, 2025.