Heavy Metal Tolerance of Klebsiella pneumoniae Kpn555 Isolated from Coffee Pulp Waste

  • APARNA K MOHAN
  • SHINY MARTIS B
  • SANJANA CHIPLUNKAR
  • SANDHYA KAMATH
  • LOUELLA CONCEPTA GOVEAS
  • C VAMAN RAO

Abstract

Microorganisms gain the ability to tolerate complex pollutants such as heavy metals, pesticides and polyaromatic hydrocarbons on continual exposure to them. The ability of indigenous microorganisms in tolerance and degradation of persistent xenobiotics has been frequently exploited. Coffee pulp waste is known to contain trace amounts of heavy metals attributing to residues from agro industrial activities. In the present study, a Gram negative non motile rod shaped bacterium, isolated from coffee pulp waste, showed tolerance to heavy metals such as cadmium (Cd), lithium (Li) and mercury (Hg). It was identified as Klebsiella pneumoniae Kpn555 by 16s RNA sequencing. The bacterium showed a minimum inhibitory concentration of 150 mg/L, 250 mg/L and 10 mg/L of Cd, Li and Hg, respectively. When the bacterium was grown in nutrient broth supplemented with concentrations of Hg (5 and 10 mg/L), Cd (50 and 100 mg/L) and Li (100 and 200 mg/L), it was observed that the growth reduced with the increase in concentration of heavy metals. The residual heavy metal concentration in the cell free supernatant was determined and the percentage of reduction in the concentration of heavy metals was calculated. It was observed that the cell free broth had a reduction of 54.8%, 50.6% and 40.6% of Li, Cd and Hg, respectively. This means that the bacterium has adsorbed the heavy metals from the medium onto their cell wall or inside the cytoplasm. This study revealed that K. pneumoniae Kpn555 has multi heavy metal resistance which could be utilised for bioremediation of soil and water polluted with multiple heavy metals.

Published
2019-12-31
Section
General