Resistance of Halobacterium strain R1 to cadmium during growth in mineral salts medium devoid of growth factors

Abstract

Growth of Halobacterium strain R1 an archaeal isolate from the Ribandar salt pan of the Mandovi estuary in Goa, India was studied for its response to Cd+2 ions, during growth in nutrient rich medium with 25 percent crude salt (NTYE) and on laboratory formulated mineral salts medium with 20 percent NaCl and 0.2 percent glucose as sole source of carbon (NGSM). Increasing concentrations of 1mM - 4mM Cd+2 in NTYE extended the lag phase, the log phase and retarded the growth rate of the culture, while 5mM Cd+2 totally abolished growth. A maximum of 1 mM Cd+2 ions in mineral salts medium stimulated growth and pigmentation of the haloarchaeon whereas a 2.5 mM concentration was inhibitory. The MIC of 2.5 mM Cd+2, in mineral salts medium, devoid of growth factors, although 50 percent less than that observed in NTYE reflects undoubtedly the True MIC for the culture.