RESISTANCE OF HALOBACTERIUM STRAIN R1 TO CADMIUM DURING GROWTH IN MINERAL SALTS MEDIUM DEVOID OF GROWTH FACTORSJUDITH M. BRAGANCA# AND IRENE FURTADOAbstract 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% crude salt (NTYE) and on laboratory formulated mineral salts medium with 20% NaCl and 0.2% 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% less than that observed in NTYE reflects undoubtedly the True MIC for the culture.
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