https://doi.org/10.17113/ftb.63.03.25.8727

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Screening of Moderately Halophilic Bacteria Producing Ectoine Resulting in Selection of Virgibacillus salarius BHTA19

Martyna Leszczewicz^*, Natalia Broncel, Oliwia Frączak, Tomasz Kapela and Krzysztof Makowski

Biotechnika Poland Ltd., Tymienieckiego 25, 90-350 Lodz, Poland

Copyright © 2024 This is a Diamond Open Access article published under CC-BY licence. Copyright remains with the authors, who grant third parties the unrestricted right to use, copy, distribute and reproduce the article as long as the original author(s) and source are acknowledged.

Article history:

Received: 3 June 2024

Accepted: 18 February 2025

Keywords:

halophilic bacteria; ectoine; hydroxyectoine; biosynthesis; screening

Summary:

Research background. Ectoine is a desirable molecule with high application potential, particularly in the cosmetics and pharmaceutical industries. The current production method involves microorganisms that require high salinity. Therefore, product purification is expensive, complex, and requires proper equipment. To overcome these obstacles, we were searching for new moderately halophilic, ectoine-producing bacteria.

Experimental approach. The bacteria were isolated from high salinity environments: the vicinity of Tyrawa Spring, Złockie vicinity of Na Mokradłach Spring, and Rajcza all in Poland. Their capacity for biosynthesizing ectoine and additionally hydroxyectoine in a 10 % premixed seawater environment was assessed semi-quantitatively using mass spectrometry (MS). The growth of bacteria was also compared under these conditions. Then the most promising strains were identified based on 16S rDNA sequence, and their morphological, biochemical, and physiological features were described. The biosynthesis of ectoine was conducted based on the collected data and the preferences of individual strains. Final product concentrations were estimated by HPLC. Following the screening process, the most suitable strain was pointed out.

Results and conclusions. Fifty-six bacterial strains were isolated. Most produced insignificant amounts of ectoine or hydroxyectoine in the presence of 10% salt. However, ten, all isolated from Tyrawa Spring, showed promising properties and were used in further studies. Based on the 16S rDNA sequence four were as assigned as Halobacillus sp., two Virgibacillus sp. and one from Bacillus sp., Pseudalkalibacillus sp., Salimicrobium sp. and Thalassobacillus sp. The basic biochemical and physiological features as well as the ability to grow in the presence of NaCl, KCl, (NH₄)₂SO₄ and MgSO₄ were described. The biosynthesis of ectoine was conducted following the best parameters estimated for each strain. Based on the results Virgibacillus salarius BHTA19 was singled out as a new potential producer of ectoine.

Novelty and scientific contribution. We isolated promising ectoine producer, moderately halophilic bacteria - Virgibacillus salarius BHTA19. The BHTA19 is a wild-type strain that produces significant quantities of ectoine in environments with moderate salt concentrations. It shows great potential and possibility of industrial application.