GRAM NEGATIVE BACTERIUM CARRING TRANSFERABLE IRON RESISTANT MARKER AND SOME FACTORS AFFECTING TRANSFER FREQUENCY
Authors: Shahid Hasnain and Anjum Nasim Sabri
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From the effluents of Comfort Chemicals, a bacterium, AnFe-6, which could deter FeCl3 up to 2500 µg ml-1 was isolated. It had circular, convex, entire, off-white opaque colonies. Cells of AnFe-6 were Gram-negative, motile, pleomorphic, rods. It confers resistance to antibiotics, ampicillin (Ap) and chloramphenicol (Cm) and other metallic salts (Ba+2, Zn+2, Ni+2, Co+2, Cu+2, Hg+2, Mn+2 and Sn+2). However it was sensitive to kanamycin (Km), tetracycline (Tc) and streptomycin (Sm) antibiotics and Hg+2 salt. It favours neutral to alkaline pH (7.0 – 7.5) for its growth. It could respire anaerobically, had oxidase and urease activity. AnFe-6 could produce acid from arabinose, glucose and rhamnose. The isolate gave positive results for ONPG, Lysine decarboxylase, gelatin hydrolysis, ornithine decarboxylase and arginine dihydrolase tests. On the basis of these characters the isolate could be affiliated to family Vibrionaceae. By the gel electrophoresis of total cell lysate, no plasmid band was detected in this strain, but conjugation experiments revealed the presence of transferable iron resistance marker, genetic determinant for which has to be established. Minimum of 8 hours were required to establish mating aggregates. Conjugal transfer of genetic element carrying iron resistant marker was affected by donor and recipient proportion, temperature as well as pH of mating mixture. 25 oC inconcomitant with pH 8 showed synergistic response for conjugal transfer.