A study of biofilm production by a multi-metal tolerant strain of Klebsiella sp.

Heavy metals, released from various industries and mines impart significant adverse effects in the environment. Biofilms, produced by microbes have been found to be suitable for the remediation of pollutants because of their high microbial biomass and ability to immobilize pollutants. In the present study a newly isolated strain of Klebsiella sp PRBC 14 showed remarkable efficacy to tolerate heavy metals like Aluminum, Manganese, Zinc, Stannous, Silver, Nickel, Ferric, Ferrous, Lead, Cadmium, Cr(III), Cr(VI), Copper, Cobalt, Arsenate and Arsenite in high concentration. The cells showed a tendency to form biofilm in presence of these metal ions, which varied with the nature of the metal ion present in the medium. The photo-micro-graphic studies revealed that in most cases, the bacterial cells were caught in the sticky slime and managed to escape the toxic effect of heavy metals. In some cases the sequestering of metal ions from the media was accomplished by trapping of the salts in the extra polysaccharide matrix of the biofilm.