Abstract
Abstract - In the present study, a pure culture of bacterium ( Pseudomonas sp. Strain NBM11) was isolated from the soil sample from a site contaminated with medical wastes and wastewater. The isolated strain can degrade up to 1000 mg/L of phenol completely. It was observed that temperature, pH and initial concentration of phenol play key roles in determining the rate of phenol degradation. The isolated strain exhibited the maximal degradation of the substrate within a range of pH 6.8 to 7.2 and an incubation temperature between 30 oC and 32 oC. It was found that by increasing the concentration of phenol, the lag phase gets extended due to the inhibitory nature of phenol. The kinetic parameters such as µ max (maximum specific growth rate), K s (half-saturation coefficient) and K i (substrate inhibition constant) were estimated as 0.184 1/h, 7.79 mg/L and 319.24 mg/L, respectively, by fitting the growth kinetics data to the Haldane model of substrate inhibition. The bacterial strain was immobilized in alginate beads and its phenol degradation efficiency was observed to increase many fold. The immobilized cells were found to be used efficiently for seven cycles consecutively without any decrease in their efficiency.
Highlights
Phenol is the basic structural unit of a wide variety of synthetic organics (Agarry and Solomon 2008) (Agarry et al, 2008)
The growth kinetic parameters such as maximum specific cell growth rate, substrate affinity constant (KS), and substrate inhibition constant (Ki) specify the efficiency of the biodegradation process and vary over a wide range depending upon the microorganism and culture conditions (Banerjee and Ghoshal 2010)
Only six bacterial strains demonstrated more than 80% phenol degradation
Summary
Phenol is the basic structural unit of a wide variety of synthetic organics (Agarry and Solomon 2008) (Agarry et al, 2008). It is a listed priority pollutant by the U.S Environmental Protection Agency and Agency for Toxic Substances and Disease Registry (Services 2003). To remove higher concentration of phenol from effluents, it is peculiarly significant to isolate appropriate microorganism that can endure as well as effectively degrade phenol at relatively high concentration. The growth kinetic parameters such as maximum specific cell growth rate (μmax), substrate affinity constant (KS), and substrate inhibition constant (Ki) specify the efficiency of the biodegradation process and vary over a wide range depending upon the microorganism and culture conditions (Banerjee and Ghoshal 2010)
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