Nickel-resistant bacteria from Cuban laterite soils

The metallurgic industry is a high risk environmental factor because of the disposal of toxic heavy metals. This is the case of the Cuban nickel indus try, one of the main sources of Cuban economy. In a future, alternative met hods for the treatment of nickel ores have to be developed. In this sense, studies on nickel-resistant bacteria are rather scarce. The aim of this work was to select nickel-resistant bacteria and to study t heir physiology and some molecular characteristics. The disk-diffusion method was used for screening the effect of nickel on th e microorganism. Thirty heterothophic bacteria were isolated from the later ite deposits at Moa (Cuba). Among them, three were resistant to nickel. The se strains were classified by the Enterotube II method as Serratia marcesce ns, Enterobacter agglomerans and Pseudomonas maltophilia. Serratia marcescens strain was able to tolerate up to 25 mM nickel. The pre sence of nickel altered the protein profile in SDS-PAGE. The results indica te that these strains might contain plasmid DNA of high molecular weight. Results show that the nickel resistance varies among different bacteria and within strains from the same species in close relation to their natural ha bitat.