POTENTIAL OF Lysinibacillus fusiformis 5B AND ITS IMMOBILIZED UREASE FOR DETECTION AND BIOSORPTION OF SELECTED HEAVY METALS

Abstract

Ureases are a group of enzymes that hydrolyse urea producing carbon dioxide and ammonia. Urease producing bacteria have been hypothesized to have inherent bioremediation abilities. The aim of this research was to detect heavy metals in solution using immobilized urease produced by Lysinibacillus fusiformis 5B and determine its potential to biosorp lead (Pb), chromium (Cr), cadmium (Cd) and nickel (Ni). Urease produced by L. fusiformis 5B was immobilized on 1cm x 6cm strips using tris-acetate buffer, and phenol red in 10 % glutaraldehyde solution for detection of the heavy metals. L. fusiformis 5B was screened for the potential to utilize 5 ppm of each heavy metal using agar dilution method. Broth of L. fusiformis 5B was inoculated to 10, 15, 20 and 50 ppm of the heavy metals. The rate of biosorption was determined by atomic absorption spectroscopy (AAS) after 0, 7, 14, 21, 28 and 35 days. The percentage (%) biosorption was determined by Beer Lambert’s equation. Detection strips showed varying degrees of magenta compared to standard color chart for the quantification of the heavy metals in solution. L. fusiformis 5B was able to tolerate 5 ppm concentration of all the heavy metals. There was an increase in biosorption rate as the time (days) progressed. The highest biosorption for 10, 15, 20 and 50 ppm was chromium with 99.97 %, lead with 99.89 %, chromium with 99.93 % and cadmium with 97.23 %, respectively, after 35 days. There was a significant difference (P<0.05) between the biosorption capacity of the isolate as the time (days) progressed. The results of this study showed that immobilized urease produced by L. fusiformis 5B was able to detect Pb, Cr, Cd and Ni and can be developed for real-time testing and sensors device to detect these heavy metals in solution. In addition, L. fusiformis 5B possessed the capacity to biosorp Pb, Cr, Cd and Ni and can be developed as biosorption agent for these heavy metals.