*For correspondence: gunay_a-va1995@mail.ru
Gunay Abbasli: https://orcid.org/0000-0003-2015-4720 Farayat Ahmadova: https://orcid.org/0009-0003-5834-5386
The work is devoted to the study of the biological properties of strains of thermophilic bacteria isolated from hot springs of Azerbaijan for their taxonomic identification. Strain B1 was isolated from the Babazanan hot spring in the Salyan district, strains KA2 and KY2, from the Ashagi Istisu and Yukhari Istisu springs in the Kalbajar district, respectively. As a result of studying the morphology of the strains, it was established that the bacterial cells are gram-positive rods that form endospores. The cultural properties of the strains were generally similar, characterized by a milky color, round shape, raised surface, wavy edges and soft consistency. Physiological studies have shown that the strains efficiently utilize organic acids, alcohols, and sugars as carbon sources. They also demonstrate effective utilization of both organic and inorganic nitrogen sources. The optimal temperature for the growth of strains was 55-60℃, and the optimal pH value was 7.0-9.0. According to biochemical characteristics, the strains were catalase-positive, while oxidase activity was absent. Proteolytic activity was observed in strains KA2 and KY2 but not in strainB1.The absence of hydrogen sulfide synthesis indicates that these strains are safe for use in biotechnological purposes. As a result of a general analysis of morphological, cultural, physiological and biochemical characteristics, the isolates were attributed to the genus Bacillus. The adaptation of these bacteria to extremophilic conditions, along with their non-pathogenic nature and metabolic flexibility, forms a solid foundation for their application in biotechnology and nanobiotechnology – particularly in the environmentally safe synthesis of metal nanoparticles.
The authors would like to express their sincere appreciation to the staff of the Department of Biology, Baku State University, for their technical support and access to laboratory facilities.
Sample collection was conducted in accordance with local environmental regulations and with respect for natural habitats. All laboratory procedures complied with standard microbiological safety and biosafety guidelines. The studied bacterial strains were confirmed to be non-pathogenic, and no genetically modified organisms were produced during the course of this research.
This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.
The authors declare that there are no conflicts of interest related to this study. The authors confirm that they have no financial or personal relationships that could have influenced the research outcomes or interpretation of the results.
Aanniz T., Ouadghiri M., Melloul M., Swings J., Elfahime E., Ibijbijen J., Ismaili M., Amar M. (2015) Thermophilic bacteria in Moroccan hot springs, salt marshes and desert soils. Braz. J. Microbiol., 46(2):443-453.
Ahmadova F.R. (2007) Some physiological and biochemical characteristics of Bacillus species distributed in thermal waters of the Republic of Azerbaijan. Reports of the National Academy of Sciences of Azerbaijan, LXIII(2): 79-83.
Brumm P.J., Budzik J.M., Krumholz L.R., Dees P.M., Bryant D.A. (2010) Carbohydrate-active enzymes from pigmented Bacilli: a genomic approach to assess carbohydrate utilization and degradation. BMC Genomics, 11: 98.
Brock T.D. (1978) Thermophilic microorganisms and life at high temperatures. Springer-Verlag: 465 p.
Deljou А., Samad Goudarzi (2016) Green extracellular synthesis of the silver nanoparticles using thermophilic Bacillus sp. AZ1 and its antimicrobial activity against several human pathogenetic bacteria. Iran. J. Biotech., 14(2): e1259, 25-32.
Gudzenko O.V., Varbanets L.D., Avdiyuk K.V., Pasichnyk L.A. (2023) Proteolytic activity of Bacillus strains isolated from rice agrocenosis soil. Mikrobiolohichnyi Zhurnal, 85(6): 41–47.
Gunashova G.Y., Ahmadova F.R., Khalilov R.I. (2021) Thermophilic bacteria of the hot springs “Ashagi Istisu” and “Yukhari Istisu” of the Kalbajar region of the Republic of Azerbaijan. Journal of Life Sciences & Biomedicine, 3(76), No 2: 134-140.
Gunashova G.Y., Ahmadova F.R., Khalilov R.I. (2021). Biosynthesis of silver nanoparticles using thermophilic Bacillus sp. B1. Advances in Biology & Earth Sciences, 6(2): 142-145.
Gunashova G.Y. (2022) Synthesis of silver nanoparticles using a thermophilic bacterium strain isolated from the spring Yukhari Istisu of the Kalbajar region (Azerbaijan). Advances in Biology & Earth Sciences,7(3):198-204.
Hajiyeva A., Mamedov Ch., Gasimov E., Rzayev F., Isayev O., Khalilov R., Eftekhari A., Benis Kh.Z. (2024) Ultrastructural investigation of iron oxide nanoparticles accumulation in the liver of common carp (Cyprinus carpio Linnaeus, 1758). Aquatic Toxicology, 272:106961; doi: 10.1016/j.aquatox.2024.106961
Holt J.G., Krieg N.R., Sneath P.H.A., Staley J.T., Williams S.T. (1994) Bergey’s manual of determinative bacteriology (9th ed.). Williams & Wilkins. 787 p.
Iravani S., Korbekandi H., Mirmohammadi S. V., Zolfaghari B. (2014) Synthesis of silver nanoparticles: Chemical, physical and biological methods. Research in Pharmaceutical Sciences,9: 385–406; PMID: 26339255
Kamal A. (2012) Kalbajar Battalion and the Legendary Regiment. Baku: Azernashr, 330p. (in Azerbaijani).
Lavrenchuk L.S., Ermoshin, A.A. (2019) Microbiology: Practical Course. Ministry of Science and Higher Education of the Russian Federation, Ural Federal University Publishing: Yekaterinburg, 107p.
Libor S.M., Sundaram T.K., Scrutton M.C. (1978) Pyruvate carboxylase from a thermophilic Bacillus. Studies on the specificity of activation by acyl derivatives of coenzyme A and on the properties of catalysis in the absence of activator. Biochemical Journal, 169(3): 543-558; doi: 10.1042/bj1690543
Liu X., Zhang H., Chen Y., Wang J. (2025) Optimization of the fermentation culture conditions of Bacillus amyloliquefaciens CK 05 using response surface methodology. Frontiers in Microbiology, 16: Article 1552645.
Logan N.A. (2012) Bacillus and relatives in foodborne illness. Journal of Applied Microbiology, 112(3): 417–429.
Logan N.A., De Vos P. (2009) Bacillus. In: Bergey's Manual of Systematic Bacteriology, 2nd ed. Springer, 3: 21-128.
Madigan M.T., Martinko J.M., Bender K.S. (2019) Brock Biology of Microorganisms. 15th ed.). Pearson: 104 p.
Marzban G., Tesei D. (2025) The Extremophiles: Adaptation mechanisms and biotechnological applications. Biology, 14(4): 412;doi: 10.3390/biology14040412
Rzayev F.H., Gasimov E.K., Agayeva N.J., Manafov A.A., Mamedov C.A., Ahmadov I.S., Khusro A., Arasu M.V., Sahibzada M.U.K., Al-Dhabi N.A., Choi K.C. (2022) Microscopic characterization of bioaccumulated aluminium nanoparticles in simplified food chain of aquatic ecosystem. Journal of King Saud University – Science,34(1): 1-8 (Art. No 101666).
Sonenshein A.L., Losick R., Hoch, J.A. (Eds.). (1993) Bacillus subtilis and other Gram-positive bacteria: Biochemistry, physiology, and molecular genetics. American Society for Microbiology, 987 p.
Sreekanth M.S., Vijayendra S.V.N., Joshi G.J. (2013) Effect of carbon and nitrogen sources on simultaneous production of α amylase and polyhydroxyalkanoates by Bacillus sp. CFR 67. Journal of Food Science and Technology, 50(2): 278–286; doi: 10.1007/s13197-012-0639-6.
Sulaiman G.M., Tawfeeq A.T., Naji A.S. (2018) Extracellular biosynthesis of magnetic iron oxide nanoparticles by Bacillus cereus strain HMH1: characterization and in vitro cytotoxicity analysis on MCF 7 and 3T3 cell lines. Artificial Cells, Nanomedicine, and Biotechnology, 46(6): 1215-1229; doi: 10.1080/21691401.2017.1366335
Zeigler D.R. (2011) The genus Bacillus: Agriculture and biotechnology. In: Bacillus: Cellular and Molecular Biology. Norfolk, UK: Horizon Scientific Press, pp. 1–18. doı:10.1201/9781420009330.ch24.
Received: September 29, 2025; Received in revised form: November 20, 2025; Accepted: December 11, 2025
DOI:
https://doi.org/10.62088/timbb/9.2.8Keywords:
Genus Bacillus, morphological characterization, thermophilic enzymatic activity, physiological traits of thermophiles, biochemical characterization
Abbasli, G., Ahmadova, F.. (2025). BIOLOGICAL CHARACTERIZATION OF THERMOPHILIC BACTERIAL STRAINS FROM HOT SPRINGS IN THE REPUBLIC OF AZERBAIJAN. TIMBB, 9 (2), 61-68.