Anion-type modulates the effect of salt stress on saline lake bacteria

Bianka Csitári,Hajnalka Nagy,Tamás Felföldi,Anna Bedics,Anna J Székely,Emil Boros,István Máthé

doi:10.1007/s00792-022-01260-5

Abstract

Beside sodium chloride, inland saline aquatic systems often contain other anions than chloride such as hydrogen carbonate and sulfate. Our understanding of the biological effects of salt composition diversity is limited; therefore, the aim of this study was to examine the effect of different anions on the growth of halophilic bacteria. Accordingly, the salt composition and concentration preference of 172 strains isolated from saline and soda lakes that differed in ionic composition was tested using media containing either carbonate, chloride or sulfate as anion in concentration values ranging from 0 to 0.40 mol/L. Differences in salt-type preference among bacterial strains were observed in relationship to the salt composition of the natural habitat they were isolated from indicating specific salt-type adaptation. Sodium carbonate represented the strongest selective force, while majority of strains was well-adapted to growth even at high concentrations of sodium sulfate. Salt preference was to some extent associated with taxonomy, although variations even within the same bacterial species were also identified. Our results suggest that the extent of the effect of dissolved salts in saline lakes is not limited to their concentration but the type of anion also substantially impacts the growth and survival of individual microorganisms.

Highlights

According to a conventional definition, saline lakes have a salinity of at least 3 g/L (Williams 1996)
Bacillales were the most common strains only in the collections isolated from the Kiskunság soda pans (90% of Kiskunság strains), while among the strains from Vojvodina and Transylvania proteobacterial strains were present in greater numbers (64% and 40%, respectively)
In this study we demonstrated that the salt tolerance of strains isolated from saline lakes with different salt composition depends on the concentration of salt in the media and the anion composition of the salt

Summary

Introduction

According to a conventional definition, saline lakes have a salinity of at least 3 g/L (Williams 1996). Inland saline lakes occur on every continent (Hammer 1986; Sorokin et al 2014; Waiser and Robarts 2009), and their total number. Shallow saline lakes are exposed to the effect of precipitation and evaporation induced water level fluctuation with droughts leading to drastic increases in salinity and even periodical complete desiccation (Hammer 1986; Waiser and Robarts 2009; Schagerl 2016; Szabó et al 2020), while unrestricted water withdrawals from the watershed (e.g., irrigation) can cause increases in salinity (Liu et al 2020)

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