Study on mechanism of cobalt resistance in Enterobacter species

Authors : Nirbhavane H M, Bagde U S

DOI : 10.18231/2394-5478.2019.0006

Volume : 6

Issue : 1

Year : 2019

Page No : 22-29

The aim of this study was to understand the mechanism of resistance in Enterobacter spp. towards cobalt toxicity. The MIC (minimum inhibitory concentration) and cobalt tolerance determination was done. The cellular biochemistry of this microorganism was checked with the help of estimations of macromolecules, dehydrogenases activity, and determination of cobalt through cell fractionation. Cobalt inhibited the growth and viability of sensitive organisms. Addition of cobalt affected the growth curve phases, which was ultimately an impact of concentration of cobalt. The minimum inhibitory concentration (MIC) determined was 250 ppm in sensitive Enterobacter spp. that completely inhibited the growth, synthesis of protein, DNA, and activity of dehydrogenases of the TCA cycle. The resistant Enterobacter spp. tolerated even 500 ppm concentration of cobalt. The cobalt incorporated in to the cell wall, membrane and cytoplasm was 66%, 11% and 23% and 9%, 58% and 33% in resistant Enterobacter spp. and sensitive Enterobacter spp. respectively when 250 ppm cobalt was added in the culture flasks. The mechanism of resistance was accumulation of cobalt in the cell wall and presence of plasmid.

Keywords: Cobalt, Resistant enterobacter, Sensitive enterobacter, Mechanism, Inhibition.

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