Abstract

Introduction. The development of new technologies of bacterial cultures for fish products is an important area of re-search. Sodium chloride (NaCl) has an inhibitory effect on most microorganisms and is often used in fish industry. The present research objective was to study the effect of NaCl on the growth of lactic acid bacteria of the species Lactoba-cillus sakei. Study objects and methods. The research featured strains of lactic acid bacteria L. sakei (L. sakei LSK-45 and L. sakei DSM 20017). The bacteria were cultivated in a semi-liquid MRS medium supplemented with sodium chloride at vari-ous concentrations. The optical density (OD) of the medium and the viable cell counts served as indicators of bacterial growth. The morphology of bacterial cells was studied by microscopic examination of Gram-stained bacteria. Results and discussion. Both L. sakei strains proved tolerant to NaCl concentrations up to 6% as proved by the high density of the cell population – 109 CFU/cm3. When NaCl concentration reached 10%, L. sakei LSK-45 demonstrated the highest resistance to osmotic stress. At the end of cultivation, the population density dropped to 108 CFU/cm3, and the survival rate was 92%. The number of viable cells of L. sakei DSM 20017 decreased to 106 CFU/cm3, and the sur-vival rate reached 62%. The high resistance of L. sakei LSK-45 to osmotic stress was caused by cell cohesion, which increased with the growing NaCl concentration and was regulated by the quorum sensing system. Conclusion. L. sakei showed a flexible response to the changes in NaCl concentration. L. sakei LSK-45 strain had the highest resistance to osmotic stress.

Keywords

Lactobacillus sakei, sodium chloride, lactic acid bacteria, osmotic stress, salt, salt stress, cultivation

REFERENCES

1. Skåra T, Axelsson L, Stefansson G, Ekstrand B, Hagen H. Fermented and ripened fish products in the northern European countries. Journal of Ethnic Foods. 2015;2(1):18–24. https://doi.org/10.1016/j.jef.2015.02.004.
2. Zang J, Xu Y, Xia W, Regenstein JM. Quality, functionality, and microbiology of fermented fish: a review. Critical Reviews in Food Science and Nutrition. 2020;60(7):1228–1242. https://doi.org/10.1080/10408398.2019.1565491.
3. Nikiforova A, Zamaratskaia G, Pickova J. Fatty acid composition of salted and fermented products from Baikal omul (Coregonus autumnalis migratorius). Journal of Food Science and Technology. 2020;57(2):595–605. https://doi.org/10.1007/s13197-019-04091-z.
4. Speranza B, Racioppo A, Bevilacqua A, Beneduce L, Sinigaglia M, Corbo MR. Selection of autochthonous strains as starter cultures for fermented fish products. Journal of Food Science. 2015;80(1):M151–M160. https://doi.org/10.1111/1750-3841.12721.
5. Kongkiattikajorn J. Potential of starter culture to reduce biogenic amines accumulation in som-fug, a Thai tradi-tional fermented fish sausage. Journal of Ethnic Foods. 2015;2(4):186–194. https://doi.org/10.1016/j.jef.2015.11.005.
6. Bjerke GA, Rudi K, Avershina E, Moen B, Blom H, Axelsson L. Exploring the brine microbiota of a traditional Norwegian fermented fish product (Rakfisk) from six different producers during two consecutive seasonal productions. Foods. 2019;8(2). https://doi.org/10.3390/foods8020072.
7. Song E-J, Lee E-S, Park S-L, Choi H-J, Roh SW, Nam Y-D. Bacterial community analysis in three types of the fermented seafood, jeotgal, produced in South Korea. Bioscience, Biotechnology and Biochemistry. 2018;82(8):1444–1454. https://doi.org/10.1080/09168451.2018.1469395.
8. Zagorec M, Champomier-Vergès M-C. Lactobacillus sakei: A starter for sausage fermentation, a protective cul-ture for meat products. Microorganisms. 2017;5(3). https://doi.org/10.3390/microorganisms5030056.
9. Magdanova LA, Golyasnaya NV. Heterogeneity as an adaptive trait of microbial populations. Microbiology. 2013;82(1). (In Russ.). https://doi.org/10.7868/S0026365613010072.
10. Wu P, An J, Chen L, Zhu Q, Li Y, Mei Y, et al. Differential analysis of stress tolerance and transcriptome of pro-biotic Lacticaseibacillus casei zhang produced from solid-state (SSF-SW) and liquid-state (LSF-MRS) fermentations. Microorganisms. 2020;8(11). https://doi.org/10.3390/microorganisms8111656.
11. Van de Guchte M, Serror P, Chervaux C, Smokvina T, Ehrlich SD, Maguin E. Stress responses in lactic acid bac-teria. Antonie van Leeuwenhoek, International Journal of General and Molecular Microbiology. 2002;82(1–4):187–216. https://doi.org/10.1023/A:1020631532202.
12. Papadimitriou K, Alegria A, Bron PA, De Angelis M, Gobbetti M, Kleerebezem M, et al. Stress physiology of lactic acid bacteria. Microbiology and Molecular Biology Reviews. 2016;80(3):837–890. https://doi.org/10.1128/MMBR.00076-15.
13. Oleskin AV. Biosocial phenomena in unicellular organisms (exemplified by data concerning Prokaryota). Jour-nal of General Biology. 2009;70(3):225–238. (In Russ.).
14. Nikolaev YuA. Extracellular factors of bacterial adaptation to unfavorable environmental conditions. Applied Biochemistry and Microbiology. 2004;40(4):387–397. (In Russ.).
15. Abaturov AE, Kryuchko TA. Inhibition of bacterial quorum sensing (general concept). Child`s health. 2019;14(1):54–59. (In Russ.). https://doi.org/10.22141/2224-0551.14.1.2019.157881.
16. Gu Y, Li B, Tian J, Wu R, He Y. The response of LuxS/AI-2 quorum sensing in Lactobacillus fermentum 2-1 to changes in environmental growth conditions. Annals of Microbiology. 2018;68(5):287–294. https://doi.org/10.1007/s13213-018-1337-z.
17. Zhao X, Yu Z, Ding T. Quorum-sensing regulation of antimicrobial resistance in bacteria. Microorganisms. 2020;8(3). https://doi.org/10.3390/microorganisms8030425.
18. Kareb O, Aïder M. Quorum sensing circuits in the communicating mechanisms of bacteria and its implication in the biosynthesis of bacteriocins by lactic acid bacteria: A review. Probiotics and Antimicrobial Proteins. 2020;12(1):5–17. https://doi.org/10.1007/s12602-019-09555-4.
19. Shipko ES, Duvanova OV. Changing the spectrum of fatty acids as one of the mechanisms of adapta-tion/persistence of microorganisms. Journal of Microbiology Epidemiology Immunobiology. 2019;(5):109–118. (In Russ.). https://doi.org/10.36233/0372-9311-2019-5-109-118.
20. Montanari C, Barbieri F, Magnani M, Grazia L, Gardini F, Tabanelli G. Phenotypic diversity of Lactobacillus sakei strains. Frontiers in Microbiology. 2018;9. https://doi.org/10.3389/fmicb.2018.02003.