Behavior Assessment of Moderately Halophilic Bacteria in Brines Highly Enriched with Heavy Metals: Sfax solar saltern (Tunisia), A Case Study

This study, based on complementary descriptive and analytical approaches, focuses on the behavior of moderately halophilic Bacteria toward selected heavy metals (Zn, Cd, Cu and Pb) in Sfax solar saltern brines (Tunisia). The brines metal concentrations (mg/L) varied from 0.065 to 1.57 for Zn, 0.002–0.034 for Cd, 0.006–0.064 for Cu and 0.002–0.128 for Pb. Analyzed metals have been ranged in the following order: Zn > Pb > Cu > Cd. Computed enrichment factors (EFs) showed a significant contamination of brines due the impact of industrial particulate fallouts highly enriched with heavy metals. Multivariate statistical analysis results, concerning the principal component analysis, the hierarchical cluster analysis and the multiple regression analysis revealed that the salinity, the temperature, TOC, Pb and Cd have a negative significant influence on Bacteria growth. Only pH, O2, Zn and Cu were significant positive factors associated with their growth density. The analysis of variance applied to growth parameters of nine bacterial strains affiliated to genera Halomonas, Cobetia, Idiomarina, Marinobacter and Salinivibrio, already isolated from the brines, showed that pH values, temperature and NaCl concentrations have different effects on growth rate (pvalues Zn > Cd > Pb. Halomonas sp. K22 and Salinivibrio costicola were the most resistant strains.