Search for Antibiotic Producers Among Actimycetes Isolated from the Salt Lake Bolshoi Tambukan (Northern Caucasus)

Background. The spread of antibiotic resistance among pathogenic microorganisms is a global problem. One solution is the discovery of new, effective natural antibiotics. The aim of the study. To identify producers of these antibiotics, potential antibiotic-producing microorganisms were isolated and analyzed from natural sources with extreme environmental parameters that had not previously been studied in this regard. Twenty actinomycete isolates from the littoral zone of the Salt Lake Bolshoi Tambukan are described. Materials and Methods. Actinomycetes were identified using cultural and morphological characteristics and 16S rRNA gene analysis. Antimicrobial activity was determined in submerged cultures obtained on eight media of varying compositions. Thirteen collection microorganisms, including multidrug-resistant (MDR) bacteria, and 10 clinical MDR isolates of Klebsiella pneumoniae were used as test strains. Results. Of the 20 strains, 19 ex hibited antimicrobial properties, representing a high percentage of potential antibiotic producers (95%). In cases where multiple strains of a single species were isolated (2–3 strains each), intraspecific differences in antimicrobial spectra were observed in Micromonospora palomenae, Streptomyces badius, S. rubiginosohelvolus, and S. vastus, which contributes to the competitiveness and survival of the population as a whole. M. palomenae and S. xinghaiensis species, for which antibiotics have not previously been described, represent promising targets for chemical research. S. xinghaiensis INA 01375 and S. rubiginosohelvolus INA 01402 are of particular interest, as they are active against clinical isolates of MDR Klebsiella pneumoniae. Conclusion. The actinomycete flora of Lake Tambukan represents a promising target for the search for antibiotic producers capable of overcoming pathogen resistance.

1. WHO fungal priority pathogens list to guide research, development and public health action. Geneva: World Health Organization; 2022.

2. WHO Bacterial Priority Pathogens List, 2024: bacterial pathogens of public health importance to guide research, development and strategies to prevent and control antimicrobial resistance. Geneva: World Health Organization; 2024.

3. T. A., Terekhova L. P., Efremenkova О. V. Current state the problem of antibiotic resistance of pathogens. Antibiotiki i Khimioter = Antibiotics and Chemotherapy. 2019; 64 (5–6): 64–68. doi: https://doi.org/10.24411/0235-2990-2019-100033. (in Russian)]

4. Bérdy J. Bioactive microbial metabolites. J Antibiot (Tokyo). 2005; 58 (1): 1–26. doi: 10.1038/ja.2005.1.

5. Bérdy J. Thoughts and facts about antibiotics: where we are now and where we are heading. J Antibiot (Tokyo). 2012; 65 (8): 385–395. doi: 10.1038/ja.2012.27.

6. Jakubiec-Krzesniak K., Rajnisz-Mateusiak A., Guspiel A., Ziemska J., Solecka J. Secondary metabolites of actinomycetes and their antibacterial, antifungal and antiviral properties. Pol J Microbiol. 2018; 67 (3): 259–272. doi: 10.21307/pjm-2018-048.

7. Donald L., Pipite A., Subramani R., Owen J., Keyzers R. A., Taufa T. Streptomyces: still the biggest producer of new natural secondary metabolites, a current perspective. Microbiol Res. 2022; 13 (3): 418–465. doi: 10.3390/microbiolres13030031

8. Butler M., Blaskovich M., Cooper M. Antibiotics in the clinical pipeline at the end of 2015. J Antibiot (Tokyo). 2017; 70 (1): 3–24. doi: 10.1038/ja.2016.72.

9. Butler M., Paterson D. Antibiotics in the clinical pipeline in October 2019. J Antibiot. 2020; 73: 329–364.

10. Butler M., Henderson I., Capon R., Blaskovich M. Antibiotics in the clinical pipeline as of December 2022. J Antibiot. 2023; 76: 431–473. doi: 10.1038/s41429-023-00629-8.

11. Li W. J., Zhang Y. Q., Schumann P., Chen H. H., Hozzein W. N., Tian X. P. et al. Kocuria aegyptia sp. nov, a novel actinobacteria isolated from a saline, alkaline desert soil in Egypt. IJSEM. 2006; 56 (4): 733–737. doi: https://doi.org/10.1099/ijs.0.63876-0.

12. Silva F. S. P., Souza D. T., Zucchi T. D., Pansa C. C., de Figueiredo Vasconcellos R. L., Crevelin I. J. et al. Streptomyces atlanticus sp. nov., a novel actinomycete isolated from marine sponge Aplysina fulva (Pallas, 1766). Antonie Van Leeuwenhoek. 2016; 109 (11): 1467–1474. doi: 10.1007/s10482-016-0748-8.

13. Meklat A.,Bouras N., Mokrane S., Zitouni A., Djemouai N., Klenk H. P. et al. Isolation, classification and antagonistic properties of alkalitolerant actinobacteria from Algerian Saharan soils. Geomicrobiology Journal. 2020; 37 (9), 826–836. doi: https://doi.org/10.1080/01490451.2020.1786865.

14. Świecimska M., Golińska P., Nouioui I., Wypij M., Rai M., Sangal V. et al. Streptomyces alkaliterrae sp. nov., isolated from an alkaline soil, and emended descriptions of Streptomyces alkaliphilus, Streptomyces calidiresistens and Streptomyces durbertensis. Syst Appl Microbiol. 2020; 43: 126153. doi: 10.1016/j.syapm.2020.126153.

15. Veyisoglu A. Sahin N. Streptomyces hoynatensis sp. nov., isolated from deep marine sediment. Int J Syst Evol Microbiol. 2014; 64 (3): 819–826. doi: 10.1099/ijs.0.055640-0.

16. Anufriieva E. V.; Shadrin N. V.; Shadrina S. N. History of research on biodiversity in crimean hypersaline waters. Arid Ekosystems. 2017; 7 (1): 67–74. doi: https://doi.org/10.1134/S2079096117010036.

17. Arayes M. A., Nawar E. A., Sabry S. A., Mabrouk M. E. Bioactive compounds from a haloalkalitolerant Streptomyces sp. EMSM31 isolated from Um-Risha Lake in Egypt. Egyptian Journal of Aquatic Biology and Fisheries. 2022; 26: 307–330.

18. Cukur D., Krastel S., Schmincke H. U., Sumita M., Çağatay M. N., Meydan A. E. et al. Seismic stratigraphy of Lake Van, eastern Turkey. Quaternary Science Reviews. 2014; 104: 63–84. doi: https://doi.org/10.1016/j.quascirev.2014.07.016

19. Growth I., Schumann P., Rainey F. A., Martin K., Schuetze B., Augsten K. Bogoriella caseilytica gen. nov., sp. nov., a new alkaliphilic actinomycete from a soda lake in Africa. Int J Syst Bacteriol. 1997; 47: 788–794. doi: 10.1099/00207713-47-3-788.

20. Jones B. E., Grant W. D., Duckworth A. W., Owenson G. G. Microbial diversity of soda lakes. Extremophiles. 1998; 2: 191–200.

21. Poyraz N., Mutlu M. Alkaliphilic bacterial diversity of Lake Van/Turkey. Biological diversity and conservation. 2017; 10: 92–103.

22. Shivlata L., Satyanarayana T. Thermophilic and alkaliphilic actinobacteria: biology and potential applications. Front Microbiol. 2015; 6: 1014. doi: 10.3389/fmicb.2015.01014.

23. Georgieva M. L., Bilanenko E. N., Ponizovskaya V. B., Kokaeva L. Y., Georgiev A. A., Efimenko T. A. et al. Haloalkalitolerant fungi from sediments of the Big Tambukan Saline Lake (Northern Caucasus): Diversity and antimicrobial potential. Microorganisms. 2023; 11: 2587. doi: 10.3390/microorganisms11102587.

24. Gause G. F., Preobrazhenskaya T. P., Sveshnikova M. A., Terekhova L. P., Maksimova T. S. The guide for identification of actinomycetes. Moscow: Nauka; 1983. (in Russian)

25. Shirling E. B., Gottlieb D. Methods for characterization of Streptomyces species. International Journal of Systematic Bacteriology. 1966; 16 (3): 313–340. doi: https://doi.org/10.1099/00207713-16-3-313.

26. Glukhova A. A., Karabanova A. A., Yakushev A. V., Semenyuk I. I., Boykova Y. V., Malkina N. D. et al. Antibiotic activity of actinobacteria from digestive tract of millipede nedyopus dawydoffiae (Diplopoda) Antibiotics (Basel). 2018; 7: 94. doi: 10.3390/antibiotics7040094.

27. Lane D. J. 16S/23S rRNA sequencing. In: Stackebrandt E., Goodfellow M., editors. Nucleic Acid Techniques in Bacterial Systematics. Chichester: John Wiley & Sons; 1991; 115–147.

28. Kumar S., Stecher G., Tamura K. MEGA7: molecular evolutionary genetics analysis version 7.0 for bigger datasets. Mol Biol Evol. 2016; 33 (7): 1870–1874. doi: 10.1093/molbev/msw054.

29. Bennura T., Kumara A. R., Zinjardea S., Javdekar V. Nocardiopsis species: incidence, ecological roles and adaptations. Microbiol Res. 2015; 174: 33–47. doi: 10.1016/j.micres.2015.03.010.

30. Valagurova E. V., Kozyritskaya V. E., Iutinskaya G. A. Actinomycetes of Streptomyces genus. Kyiv: Naukova Dumka; 2003; 645. (in Russian)

31. Goodfellow M., Kämpfer P., Busse H-J., Trujillo M. E., Suzuki K., Ludwig W. et al. Bergey's manual of systematic bacteriology: Volume 5: The Actinobacteria. 2nd ed. New York: Springer; 2012.

32. Kuznetsov V. D., Sabirov S., Filippova S. N. A study on the population composition of Actinomyces tumemacerans and Actinomyces albus var. fungatus. Mikrobiologiya = Microbiology. 1978; 47 (5): 1073–1080. (in Russian)

33. Gu B., Lee J., Kim D. G., Cha Y., Oh M. K. Metabolic engineering of Micromonospora for exploring useful natural products and phytobiotic interaction. Metab Eng. 2025; 92: 39–50. doi: 10.1016/j.ymben.2025.07.005.

34. Fang B., Liu C., Guan X., Song J., Zhao J., Liu H. et al. Two new species of the genus Micromonospora: Micromonospora palomenae sp. nov. and Micromonospora harpali sp. nov. isolated from the insects. Antonie van Leeuwenhoek. 2015; 108 (1): 141–150. doi: 10.1007/s10482-015-0472-9.

35. Zhao X. Q., Li W.J., Jiao W. C., Li Y., Yuan W. J., Zhang Y. Q. et al. Streptomyces xinghaiensis sp. nov., isolated from marine sediment. Int J Syst Evol Microb. 2009; 59 (12): 2870–2874. doi: 10.1099/ijs.0.009878-0.

36. Kumar K. S., Anuradha S., Sarma G. R.,Venkateshwarlu Y., Kishan V. Screening, isolation, taxonomy and fermentation of an antibiotic producer Streptomyces xinghaiensis from soil capable of acting against linezolid resistant strains. Indian J Exp Biol. 2012; 50 (10): 718–728.

37. Adeyemo О. M., Onilude A. A. Antimicrobial metabolites profile and inhibitory activity of Streptomyces xinghaiensis-OY62 isolated from soil against indicator strains. South Asian Journal of Research in Microbiology. 2018; 1 (3): 1–15. doi: https://doi.org/10.9734/sajrm/2018/v1i3785.