Chloride dependence of growth in bacteria

Chloride is an abundant anion on earth but studies analyzing a possible function of chloride in prokaryotes are scarce. To address the question, we have tested 44 different Gram-negative and Gram-positive bacteria for a chloride dependence or chloride stimulation of growth. None required chloride for growth at their optimal growth (salt) conditions. However, in hyperosmotic media containing high concentrations of Na+, 11 bacteria (Aeromonas hydrophila, Bacillus megaterium, Bacillus subtilis, Corynebacterium glutamicum, Escherichia coli, Paracoccus denitrificans, Proteus mirabilis, Proteus vulgaris, Staphylococcus aureus, Thermus thermophilus, and Vibrio fischeri) had a strict chloride dependence for growth or were significantly stimulated by chloride. These data show that chloride is essential for growth at high salt (Na+) concentrations in various species of the domain Bacteria.